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Robotic Spacecraft (Astronomy, Planetary, Earth, Solar/Heliophysics) => Space Science Coverage => Topic started by: Star One on 01/22/2017 07:27 pm

Title: Astronomy & Planetary Science Thread
Post by: Star One on 01/22/2017 07:27 pm
Seemed a good idea to have a separate thread for miscellaneous exoplanet discoveries.

Is there a circumbinary planet around NSVS 14256825?

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The cyclic behaviour of (O-C) residuals of eclipse timings in the sdB+M eclipsing binary NSVS 14256825 was previously attributed to one or two Jovian-type circumbinary planets. We report 83 new eclipse timings that not only fill in the gaps in those already published but also extend the time span of the (O-C) diagram by three years. Based on the archival and our new data spanning over more than 17 years we re-examined the up to date system (O-C). The data revealed systematic, quasi-sinusoidal variation deviating from an older linear ephemeris by about 100 s. It also exhibits a maximum in the (O-C) near JD 2,456,400 that was previously unknown. We consider two most credible explanations of the (O-C) variability: the light propagation time due to the presence of an invisible companion in a distant circumbinary orbit, and magnetic cycles reshaping one of the binary components, known as the Applegate or Lanza-Rodono effect. We found that the latter mechanism is unlikely due to the insufficient energy budget of the M-dwarf secondary. In the framework of the third-body hypothesis, we obtained meaningful constraints on the Keplerian parameters of a putative companion and its mass. Our best-fitting model indicates that the observed quasi-periodic (O-C) variability can be explained by the presence of a brown dwarf with the minimal mass of 15 Jupiter masses rather than a planet, orbiting the binary in a moderately elliptical orbit (~ 0.175) with the period of ~ 10 years. Our analysis rules out two planets model proposed earlier.

https://arxiv.org/abs/1701.05211
Title: Exoplanet Thread
Post by: Star One on 01/26/2017 06:54 pm
Wolf 1061 unlikely to host habitable worlds.

http://www.centauri-dreams.org/?p=37016

Here's the pre-print.

Characterization of the Wolf 1061 Planetary System

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A critical component of exoplanetary studies is an exhaustive characterization of the host star, from which the planetary properties are frequently derived. Of particular value are the radius, temperature, and luminosity, which are key stellar parameters for studies of transit and habitability science. Here we present the results of new observations of Wolf~1061, known to host three super-Earths. Our observations from the Center for High Angular Resolution Astronomy (CHARA) interferometric array provide a direct stellar radius measurement of 0.3207±0.0088~R⊙, from which we calculate the effective temperature and luminosity using spectral energy distribution models. We obtained seven years of precise, automated photometry that reveals the correct stellar rotation period of 89.3±1.8~days, finds no evidence of photometric transits, and confirms the radial velocity signals are not due to stellar activity. Finally, our stellar properties are used to calculate the extent of the Habitable Zone for the Wolf~1061 system, for which the optimistic boundaries are 0.09--0.23~AU. Our simulations of the planetary orbital dynamics shows that the eccentricity of the Habitable Zone planet oscillates to values as high as ∼0.15 as it exchanges angular momentum with the other planets in the system.

https://arxiv.org/abs/1612.0934
Title: Re: Exoplanet Thread
Post by: ikke666 on 01/27/2017 04:59 pm
is there a list of stars that have planets on web?  ::) prefably with the kind of planet (gas giant, earth like,...)
Title: Re: Exoplanet Thread
Post by: testguy on 01/27/2017 05:29 pm
Try this.  Updates daily.

http://exoplanet.eu/catalog/
Title: Re: Exoplanet Thread
Post by: hop on 01/28/2017 06:00 am
There's also the NASA Exoplanet archive http://exoplanetarchive.ipac.caltech.edu/
Title: Re: Exoplanet Thread
Post by: Star One on 01/28/2017 12:13 pm
Took the Keck observatory seven years of observations to produce this.

A Four Planet System in Orbit, Directly Imaged and Remarkable

http://www.manyworlds.space/index.php/2017/01/24/a-four-planet-system-in-orbit-directly-imaged-and-remarkable/
Title: Re: Exoplanet Thread
Post by: ikke666 on 01/28/2017 03:55 pm
thanks for the sites  ;D
Title: Re: Exoplanet Thread
Post by: Star One on 02/02/2017 08:38 pm
Water spotted in the atmosphere of nearby hot Jupiter exoplanet

https://www.newscientist.com/article/mg23331111-800-water-spotted-in-the-atmosphere-of-nearby-hot-jupiter-exoplanet/
Title: Re: Exoplanet Thread
Post by: Star One on 02/13/2017 07:36 pm
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Washington, DC— An international team of astronomers released the largest-ever compilation of exoplanet-detecting observations made using a technique called the radial velocity method. They demonstrated how these observations can be used to hunt for planets by detecting more than 100 potential exoplanets, including one orbiting the fourth-closest star to our own Solar System, which is about 8.1 light years away from Earth. The paper is published in The Astronomical Journal.
The radial velocity method is one of the most successful techniques for finding and confirming planets. It takes advantage of the fact that in addition to a planet being influenced by the gravity of the star it orbits, the planet’s gravity also affects the star. Astronomers are able to use sophisticated tools to detect the tiny wobble the planet induces as its gravity tugs on the star.
The virtual mountain of data released to the public in this paper was gathered as part of a two-decade radial velocity planet-hunting program that uses a spectrometer called HIRES, mounted on the 10-meter Keck-I telescope of the W.M. Keck Observatory atop Mauna Kea in Hawaii. The compilation includes almost 61,000 individual measurements made of more than 1,600 stars. By making the data public, the team is offering unprecedented access to one of the best exoplanet searches in the world.
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One of these probable planets is around a star called GJ 411, also known as Lalande 21185. It is the fourth-closest star to our own Sun and is only about 40 percent the mass of the Sun. The planet has a very short orbital period of just under 10 days, so it is no Earth-twin. However, the inferred planet, GJ 411b, continues a trend that has been seen in the overall population of detected exoplanets: the smallest planets are found around the smallest stars.


https://carnegiescience.edu/news/team-makes-planet-hunting-group-effort-finds-more-100-candidates#
Title: Exoplanet Thread
Post by: Star One on 02/15/2017 07:11 pm
Planet-Induced Stellar Pulsations in HAT-P-2's Eccentric System

J. de Wit, N.K. Lewis, H.A. Knutson, J. Fuller, V. Antoci, B.J. Fulton, G. Laughlin, D. Deming, A. Shporer, K. Batygin, N.B. Cowan, E. Agol, A.S. Burrows, J.J. Fortney, J. Langton, A.P. Showman
(Submitted on 13 Feb 2017)

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Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet's atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet-star interactions in HAT-P-2's eccentric planetary system gained from the analysis of 350 hr of 4.5 micron observations with the Spitzer Space Telescope. The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b's 4.5 micron photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet's orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

https://arxiv.org/abs/1702.03797

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Title: Re: Exoplanet Thread
Post by: Mongo62 on 02/28/2017 07:23 pm
Towards Detection of Exoplanetary Rings Via Transit Photometry: Methodology and a Possible Candidate (https://arxiv.org/abs/1702.08252)

Abstract: Detection of a planetary ring of exoplanets remains as one of the most attractive but challenging goals in the field. We present a methodology of a systematic search for exoplanetary rings via transit photometry of long-period planets. The methodology relies on a precise integration scheme we develop to compute a transit light curve of a ringed planet. We apply the methodology to 89 long-period planet candidates from the Kepler data so as to estimate, and/or set upper limits on, the parameters of possible rings. While a majority of our samples do not have a sufficiently good signal-to-noise ratio for meaningful constraints on ring parameters, we find that six systems with a higher signal-to-noise ratio are inconsistent with the presence of a ring larger than 1.5 times the planetary radius assuming a grazing orbit and a tilted ring. Furthermore, we identify five preliminary candidate systems whose light curves exhibit ring-like features. After removing four false positives due to the contamination from nearby stars, we identify KIC 10403228 as a reasonable candidate for a ringed planet. A systematic parameter fit of its light curve with a ringed planet model indicates two possible solutions corresponding to a Saturn-like planet with a tilted ring. There also remain other two possible scenarios accounting for the data; a circumstellar disk and a hierarchical triple. Due to large uncertain factors, we cannot choose one specific model among the three.
Title: Exoplanet Thread
Post by: Star One on 03/10/2017 06:51 pm
Another close by system that may turn out to be suitable for exo-atmosphere observations.

HD 219134: A Nearby System with Multiple Transits

http://www.centauri-dreams.org/?p=37300

Here's the paper.

http://www.nature.com/articles/s41550-017-0056#references
Title: Re: Exoplanet Thread
Post by: jebbo on 03/13/2017 05:24 pm
In news other than Trappist-1, this on Kepler-444 is interesting:

https://arxiv.org/abs/1703.03417 (https://arxiv.org/abs/1703.03417)

The masses imply a density around that of water, which is quite remarkable as the planets have been at >600K for about 11 billion years ... so keeping hold of volatiles is quite a feat. Oh, it also implies an origin beyond the ice line

--- Tony
Title: Re: Exoplanet Thread
Post by: Bynaus on 03/13/2017 05:36 pm
Only the nominal densities are close to water, the uncertainties are quite high. Within only one standard deviation (68% confidence interval), the densities are between 0.5 g/cm3 and 3.5 g/cm3 (see Table 2), so a rocky composition can certainly not be excluded at this point. Like you say, it would be very surprising if such low-mass planets would have kept their volatiles at 600 K over the 11 Ga age of the system.
Title: Re: Exoplanet Thread
Post by: jebbo on 03/13/2017 05:42 pm
Absolutely ... and I'm wary of numbers from Bayesian methods (e.g. see Kass & Rafferty, 1995)

Shame the predicted RV is too low, though I wonder if at magnitude 9, we might get transmission spectroscopy


Edit: added figure from arxiv.org paper
--- Tony
Title: Re: Exoplanet Thread
Post by: Star One on 03/13/2017 08:10 pm
Quote
The search for extraterrestrial life is increasingly informed by our knowledge of exoplanets. Within three decades, we may know whether extrasolar life is rare.

http://physicstoday.scitation.org/doi/abs/10.1063/PT.3.3494#.WMbXbKSwOf8.twitter
Title: Exoplanet Thread
Post by: Star One on 03/14/2017 11:10 am
Mysterious celestial object could be an elusive brown dwarf or a free-floating planet

The object is not part of the AB Doradus moving group, as previous hypothesised.

http://www.ibtimes.co.uk/mysterious-celestial-object-could-be-elusive-brown-dwarf-free-floating-planet-1611441

More details on this topic in this article including the relevant paper.

https://phys.org/news/2017-03-mysterious-isolated-astronomers.html
Title: Re: Exoplanet Thread
Post by: Star One on 03/15/2017 08:11 pm
Not an exoplanet but an interesting star instead.

Isotope shift and search for metastable superheavy elements in astrophysical

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Spectral lines belonging to the short-lifetime heavy radioactive elements up to Es (Z=99) have been found in the spectra of the Przybylski's star. We suggest that these unstable elements may be decay products of a "magic" metastable nucleus belonging to the the island of stability where the nuclei have a magic number of neutrons N=184. The laboratory-produced nuclei have a significantly smaller number of neutrons. To identify spectra of the N=184 isotopes of these nuclei and their neutron-reach superheavy decay products in astrophysical data we calculate the isotope shift which should be added to the laboratory - measured wavelenghs. The results for the isotopic shifts in the strongest optical electromagnetic transitions in No, Lr, Nh, Fl,and Z=120 elements are presented.

https://arxiv.org/abs/1703.04250
Title: Re: Exoplanet Thread
Post by: Bynaus on 03/17/2017 06:20 am
Plenty of Earth-mass worlds around nearby red dwarfs (one of them in the HZ, 3.8 pc away).

https://arxiv.org/abs/1703.05386

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The HARPS search for southern extra-solar planets XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293

Context. Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a dozen super-Earths and Earth-mass planets (msin i<10Mearth ) around M dwarfs, with a well understood selection function. This well defined sample informs on their frequency of occurrence and on the distribution of their orbital parameters, and therefore already constrains our understanding of planetary formation. The subset of these low-mass planets that were found within the habitable zone of their host star also provide prized targets for future atmospheric biomarkers searches. Aims. We are working to extend this planetary sample to lower masses and longer periods through dense and long-term monitoring of the radial velocity of a small M dwarf sample. Methods. We obtained large numbers of HARPS spectra for the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628 and GJ 3293, from which we derived radial velocities (RVs) and spectroscopic activity indicators. We searched them for variabilities, periodicities, Keplerian modulations and correlations, and attribute the radial-velocity variations to combinations of planetary companions and stellar activity. Results. We detect 12 planets, of which 9 are new with masses ranging from 1.17 to 10.5 Mearth . Those planets have relatively short orbital periods (P<40 d), except two of them with periods of 217.6 and 257.8 days. Among these systems, GJ 273 harbor two planets with masses close to the one of the Earth. With a distance of 3.8 parsec only, GJ 273 is the second nearest known planetary system - after Proxima Centauri - with a planet orbiting the circumstellar habitable zone.

I know we already know this from Kepler, but its really astonishing how these red dwarf star systems are all choke full with massive terrestrial-to-neptunian worlds.

GJ 273 - also known as Luyten's Star - is currently located only 1.2 LY away from Procyon. It has a ca. 3 Earth-mass planet which recieves 1.06 times the solar insolation on Earth.
Title: Re: Exoplanet Thread
Post by: Star One on 03/28/2017 08:17 pm
Jason Wright investigates Przybylski’s Star.

http://sites.psu.edu/astrowright/2017/03/15/przybylskis-star-i-whats-that/
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 03/31/2017 11:55 am
Eric Mamajek‏
@EricMamajek

Fig. 7 will make #exoplanet jaws drop https://arxiv.org/abs/1703.10375 "Fulton Gap" clearly separates super-Earths & sub-Neptunes #Kepler #Keck #NASA

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We find evidence for a bimodal distribution of small planet sizes. Sub-Neptunes and super-Earths appear to be two distinct planet classes. Planets tend to prefer radii of either ∼1.3 R⊕ or ∼2.4 R⊕, with relatively few planets having radii of 1.5–2.0 R⊕.
Title: Re: Exoplanet Thread
Post by: Star One on 04/04/2017 08:35 pm
Venus 2.0 Discovered In Our Own Backyard

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And now, a team of international astronomers has announced the discovery of an extra-solar body that is similar to another terrestrial planet in our own Solar System. It’s known as Kepler-1649b, a planet that appears to be similar in size and density to Earth and is located in a star system just 219 light-years away. But in terms of its atmosphere, this planet appears to be decidedly more “Venus-like” (i.e. insanely hot!)

The team’s study, titled “Kepler-1649b: An Exo-Venus in the Solar Neighborhood“, was recently published in The Astronomical Journal. Led by Isabel Angelo – of the SETI Institute, NASA Ames Research Center, and UC Berkley – the team included researchers also from SETI and Ames, as well as the NASA Exoplanet Science Institute (NExScl), the Exoplanet Research Institute (iREx), the Center for Astrophysics Research, and other research institutions.

https://www.universetoday.com/134849/venus-2-0-discovered-back-yard/
Title: Exoplanet Thread
Post by: Star One on 04/06/2017 08:26 pm
Atmosphere around super-Earth detected

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Astronomers have detected an atmosphere around the super-Earth GJ 1132b. This marks the first detection of an atmosphere around a low-mass super-Earth, in terms of radius and mass the most Earth-like planet around which an atmosphere has yet been detected. Thus, this is a significant step on the path towards the detection of life on an exoplanet. The team, which includes researchers from the Max Planck Institute for Astronomy, used the 2.2-m ESO/MPG telescope in Chile to take images of the planet's host star, GJ 1132, and measured the slight decrease in brightness as the planet and its atmosphere absorbed some of the starlight while passing directly in front of their host star.

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The team used the GROND imager at the 2.2-m ESO/MPG telescope of the European Southern Observatory in Chile to observe the planet simultaneously in seven different wavelength bands. GJ 1132b is a transiting planet: From the perspective of an observer on Earth, it passes directly in front of its star every 1.6 days, blocking some of the star's light.

The size of stars like GJ 1132 is well known from stellar models. From the fraction of starlight blocked by the planet, astronomers can deduce the planet's size—in this case around 1.4 times the size of the Earth. Crucially, the new observations showed the planet to be larger at one of the infrared wavelengths than at the others. This suggests the presence of an atmosphere that is opaque to this specific infrared light (making the planet appear larger) but transparent at all the others. Different possible versions of the atmosphere were then simulated by team members at the University of Cambridge and the Max Planck Institute for Astronomy. According to those models, an atmosphere rich in water and methane would explain the observations very well.

The discovery comes with the usual exoplanet caveats: while somewhat larger than Earth, and with 1.6 times Earth's mass (as determined by earlier measurements), observations to date do not provide sufficient data to decide how similar or dissimilar GJ 1132b is to Earth. Possibilities include a "water world" with an atmosphere of hot steam.

The presence of the atmosphere is a reason for cautious optimism. M dwarfs are the most common types of star, and show high levels of activity; for some set-ups, this activity (in the shape of flares and particle streams) can be expected to blow away nearby planets' atmospheres. GJ 1132b provides a hopeful counterexample of an atmosphere that has endured for billion of years (that is, long enough for us to detect it). Given the great number of M dwarf stars, such atmospheres could mean that the preconditions for life are quite common in the universe.

In any case, the new observations make GJ 1132b a high-priority target for further study by instruments such as the Hubble Space Telescope, ESO's Very Large Telescope, and the James Webb Space Telescope slated for launch in 2018.

https://m.phys.org/news/2017-04-atmosphere-super-earth.html

Stargazing Live viewers find four-planet solar system via crowd-sourcing project

http://mobile.abc.net.au/news/2017-04-06/stargazing-live-four-planets-discovered-in-new-solar-system/8423142
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 04/06/2017 10:20 pm
Stargazing Live viewers find four-planet solar system via crowd-sourcing project

http://mobile.abc.net.au/news/2017-04-06/stargazing-live-four-planets-discovered-in-new-solar-system/8423142

https://www.youtube.com/watch?v=ZrFST9cvdAU

Interesting 3:2 orbital resonances between planets b and c, c and d, and d and e.
Title: Re: Exoplanet Thread
Post by: jebbo on 04/07/2017 08:50 am
Interesting 3:2 orbital resonances between planets b and c, c and d, and d and e.

A very interesting compact system around a late G dwarf, which makes these planets *hot*.  Sadly, no observed TTVs so it will be a while before we know mass/density.

Worth noting this was from the Campaign 12 raw cadence data (the processed data has not yet been released to MAST).  I'm hoping this sets a precedent for future campaigns :-)

This weekend, I'll try and produce a light curve for this one (but my raw cadence code still needs a fair bit of debug).

There are quite a few new candidates from this Exoplanet Explorers search, some in earlier quarters, so once again, the human eyeball has found things missed by the automated pipelines.  Clearly some will be false positives (BGEB contamination is most likely).

Edit: taking much longer than expected as the MAST download of the raw cadence data is glacial.

--- Tony
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 04/17/2017 08:01 am
Cross-posting from the 'NASA's Trappist-1 Announcement - Feb 22, 2017' thread.

Updated Masses for the TRAPPIST-1 Planets (arXiv) (https://arxiv.org/abs/1704.04290)

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The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30\% to nearly 100\%, with the mass of the outermost, P=18.8d, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding e<0.02 for inner six known members of the system), and we derive masses of 0.79±0.27M⊕, 1.63±0.63M⊕, 0.33±0.15M⊕, 0.24+0.56−0.24M⊕, 0.36±0.12M⊕, 0.566±0.038M⊕, and 0.086±0.084M⊕ for planets b, c, d, e, f, g, and h, respectively.

Quote
Figure 4 indicates that – to within the errors of our determinations – the four most distant planets are consistent with pure water compositions, and in any event, are substantially less dense either Mars or Venus.
Title: Re: Exoplanet Thread
Post by: Bynaus on 04/18/2017 06:52 am
Cross-posting from the 'NASA's Trappist-1 Announcement - Feb 22, 2017' thread.

Updated Masses for the TRAPPIST-1 Planets (arXiv) (https://arxiv.org/abs/1704.04290)

Quote
The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30\% to nearly 100\%, with the mass of the outermost, P=18.8d, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding e<0.02 for inner six known members of the system), and we derive masses of 0.79±0.27M⊕, 1.63±0.63M⊕, 0.33±0.15M⊕, 0.24+0.56−0.24M⊕, 0.36±0.12M⊕, 0.566±0.038M⊕, and 0.086±0.084M⊕ for planets b, c, d, e, f, g, and h, respectively.

Quote
Figure 4 indicates that – to within the errors of our determinations – the four most distant planets are consistent with pure water compositions, and in any event, are substantially less dense either Mars or Venus.

Very interesting, the densities of the planets are now (in g/cm3):

b: 3.4 +- 1.2
c: 7.63 +- 3.02
d: 3.95 +- 1.86
e: <5.71
f: 1.74 +- 0.61
g: 2.18 +- 0.28
h: <2.54

It is quite remarkable that the density drops significantly below the 3-5 range (= Earth-like, rocky planets) for the planets with equilibrium temperatures below 0°C, the freezing point of water (at 1 bar, but its quite possible that these planets have ~1 bar atmospheres). This might suggest the outer planets f,g,h are essentially super-Ganymedes.
Title: Re: Exoplanet Thread
Post by: Star One on 04/19/2017 08:54 pm
Newly Discovered Exoplanet May be Best Candidate in Search for Signs of Life

Transiting rocky super-Earth found in habitable zone of quiet red dwarf star

An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title “best place to look for signs of life beyond the Solar System”. Using ESO’s HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered a “super-Earth” orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere. This, along with the fact that it passes in front of its parent star as it orbits, makes it one of the most exciting future targets for atmospheric studies. The results will appear in the 20 April 2017 issue of the journal Nature.

The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star, named LHS 1140, in the constellation of Cetus (The Sea Monster) [1]. Red dwarfs are much smaller and cooler than the Sun and, although LHS 1140b is ten times closer to its star than the Earth is to the Sun, it only receives about half as much sunlight from its star as the Earth and lies in the middle of the habitable zone. The orbit is seen almost edge-on from Earth and as the exoplanet passes in front of the star once per orbit it blocks a little of its light every 25 days.

“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA). “We could hardly hope for a better target to perform one of the biggest quests in science — searching for evidence of life beyond Earth.”

"The present conditions of the red dwarf are particularly favourable — LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," explains team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland [2].

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere. When red dwarf stars are young, they are known to emit radiation that can be damaging for the atmospheres of the planets that orbit them. In this case, the planet's large size means that a magma ocean could have existed on its surface for millions of years. This seething ocean of lava could feed steam into the atmosphere long after the star has calmed to its current, steady glow, replenishing the planet with water.

The discovery was initially made with the MEarth facility, which detected the first telltale, characteristic dips in light as the exoplanet passed in front of the star. ESO’s HARPS instrument, the High Accuracy Radial velocity Planet Searcher, then made crucial follow-up observations which confirmed the presence of the super-Earth. HARPS also helped pin down the orbital period and allowed the exoplanet’s mass and density to be deduced [3].

The astronomers estimate the age of the planet to be at least five billion years. They also deduced that it has a diameter 1.4 times larger than the Earth — almost 18 000 kilometres. But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.

This super-Earth may be the best candidate yet for future observations to study and characterise its atmosphere, if one exists. Two of the European members of the team, Xavier Delfosse and Xavier Bonfils both at the CNRS and IPAG in Grenoble, France, conclude: “The LHS 1140 system might prove to be an even more important target for the future characterisation of planets in the habitable zone than Proxima b or TRAPPIST-1. This has been a remarkable year for exoplanet discoveries!” [4,5].

In particular, observations coming up soon with the NASA/ESA Hubble Space Telescope will be able to assess exactly how much high-energy radiation is showered upon LHS 1140b, so that its capacity to support life can be further constrained.

Further into the future — when new telescopes like ESO’s Extremely Large Telescope are operating — it is likely that we will be able to make detailed observations of the atmospheres of exoplanets, and LHS 1140b is an exceptional candidate for such studies.

http://www.eso.org/public/news/eso1712/?lang
Title: Re: Exoplanet Thread
Post by: Star One on 04/20/2017 08:58 pm
This is an excellent article on LHS 1140b including future plans for its study.

Newfound Super-Earth Boosts Search for Alien Life

Planet LHS 1140 b orbits a dim red dwarf star just 40 light-years away, making it a prime target for life-finding telescopes

https://www.scientificamerican.com/article/newfound-super-earth-boosts-search-for-alien-life/
Title: Re: Exoplanet Thread
Post by: Star One on 04/26/2017 06:52 pm
Speculations on Habitable Zone Waterworlds

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What to make of Fergus Simpson’s new paper on waterworlds, suggesting that most habitable zone planets are of this type? If such worlds are common, we may find that most planets in the habitable zones of their stars are capable of evolving life, but unlikely to host technological civilizations. An explanation for the so-called ‘Fermi Paradox’? Possibly, but there are all kinds of things that could account for our inability to see other civilizations, most of them covered by Stephen Webb in his If the Universe Is Teeming with Aliens … Where Is Everybody? (2nd ed., Springer 2015), which offers 75 solutions to the problem.

Simpson (University of Barcelona) makes his case in the pages of Monthly Notices of the Royal Astronomical Society, arguing that the balance maintained by a planetary surface with large amounts of both land and water is delicate. The author’s Bayesian statistical analysis suggests that most planets are dominated either by water or land, most likely water. Earth may, then, be something of an outlier, with most planets over 90 percent covered in water.

http://www.centauri-dreams.org/?p=37561
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 04/27/2017 01:53 am
There seems to be a confusion in terminology prevalent. Is a waterworld a world covered in water, but which, like the Earth, is predominately made of rock and metal; or is a waterworld one which is predominately made of water (ice, actually)?

I think of a waterworld as being the latter, with the former described as an oceanworld. But I could be under a misapprehension! :)
Title: Re: Exoplanet Thread
Post by: Star One on 04/27/2017 08:47 am
There seems to be a confusion in terminology prevalent. Is a waterworld a world covered in water, but which, like the Earth, is predominately made of rock and metal; or is a waterworld one which is predominately made of water (ice, actually)?

I think of a waterworld as being the latter, with the former described as an oceanworld. But I could be under a misapprehension! :)

I think of it as a watery Earth myself as that seemed to be what the article was referencing.
Title: Re: Exoplanet Thread
Post by: Star One on 04/27/2017 08:56 pm
Seems a decent summary.

New Planet Discoveries Signal a Shift in the Hunt for Alien Life

http://news.nationalgeographic.com/2017/04/new-planets-life-close-earth-space-science/
Title: Re: Exoplanet Thread
Post by: Star One on 04/28/2017 07:10 pm
Planetary Discovery around Ultracool Star

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Small planets may be common around ultracool dwarfs, an idea that previous microlensing discoveries reinforce, along with the work on protoplanetary disks and the seven planets orbiting TRAPPIST-1. As to our expectations regarding planets in the galactic bulge as opposed to the disk, the jury is still out. The planets Spitzer has thus far found in its microlensing campaign for the galactic distribution of planets are all located in the disk. We have two upcoming Spitzer microlensing campaigns, one this year and one next, which should offer additional insights. The key question: Is the galactic bulge deficient in planets?

http://www.centauri-dreams.org/?p=37573

Here is the paper.

https://arxiv.org/abs/1703.08548
Title: Exoplanet Thread
Post by: Star One on 05/03/2017 04:50 pm
Astronomers confirm nearby star a good model of our early solar system

http://www.news.iastate.edu/news/2017/05/02/eridani

More info to the above on this link.

http://www.centauri-dreams.org/?p=37606
Title: Re: Exoplanet Thread
Post by: Star One on 05/10/2017 08:46 pm
Exploring the Planet / Brown Dwarf Boundary

http://www.centauri-dreams.org/?p=37665
Title: Re: Exoplanet Thread
Post by: missinglink on 05/10/2017 09:10 pm
Poll:

If & when a future ultra-sensitive spectroscope detects chlorophyll in an exoplanet's atmosphere -- meaning ongoing photosynthesis by abundant plant life -- will NASA (plus maybe other government's space agencies) mount a hugely expensive effort (hundreds of billions of dollars) to send a robotic probe to that planet over a distance of, say, 20 lightyears? Knowing that radio transmission of results won't be received by anyone currently living? And with no guarantee of success?

Yes: Explore & investigate is in our genes, must find out if this is a Second Earth that can be our lifeboat & refuge

No: We will never leave solar system, age of discovery is over
Title: Re: Exoplanet Thread
Post by: gospacex on 05/10/2017 09:33 pm
Is it a trick question?

"(hundreds of billions of dollars) to send a robotic probe to that planet over a distance of, say, 20 lightyears" - well, such a probe could reach its destination somewhere in the year 50000, at best. Does not make sense, if you ask me...
Title: Re: Exoplanet Thread
Post by: Star One on 05/11/2017 06:20 am
Is it a trick question?

"(hundreds of billions of dollars) to send a robotic probe to that planet over a distance of, say, 20 lightyears" - well, such a probe could reach its destination somewhere in the year 50000, at best. Does not make sense, if you ask me...
Answer invent a quicker way to get there obviously.
Title: Re: Exoplanet Thread
Post by: Torbjorn Larsson, OM on 05/11/2017 11:08 am
Poll:

If & when a future ultra-sensitive spectroscope detects chlorophyll in an exoplanet's atmosphere -- meaning ongoing photosynthesis by abundant plant life -- will NASA (plus maybe other government's space agencies) mount a hugely expensive effort (hundreds of billions of dollars) to send a robotic probe to that planet over a distance of, say, 20 lightyears? Knowing that radio transmission of results won't be received by anyone currently living? And with no guarantee of success?

Yes: Explore & investigate is in our genes, must find out if this is a Second Earth that can be our lifeboat & refuge

No: We will never leave solar system, age of discovery is over

I'll echo that: Is it a trick question?

Some of the problems:
- Science & technology & societal development is not decided by polls.
- Finding biotic signatures is discovery. The (non)question is how fast this age of discovery will put up larger observatories to find out more. My guess: very quickly.

The lifeboat/refuge/faster probes perspective is Utopia fantasy, as far as I can see. [Admittedly: 1. I am tired of seeing such ideas around discussions containing a smidgen of science. The at odds juxtaposition is like scratching sounds from a window. But never mind that. 2. Something like Starshot may be feasible and complement other methods of discovery. Scaled up such can carry spores or even seeds, but not implant anything like our biosphere - such evolution will end up somewhere else in phylogenetic tree space. It would be a possible life refugia at best. But life is likely common, seeing how fast it emerged on Earth.]

Relativity physics puts a hard limit on economical expansion or 'refuge' (if not refugia) ideas. Whether or not individuals or even worlds would - like any parent - put aside resources for direct colonization is an open question.

[But I am reminded of the xkcd comic where Randall shows that on an exponential scale - the scale of economical growth - colonizing the Oort cloud is the largest effort after the Moon. From the Oort cloud the distance to the next cloud is nothing in relation. So if and when we colonize the resource full innards of Oort objects and put rocket engines on the outside - because orbiting is such a bounded life - I expect we will seed the galaxy. My guess: it will happen. But I do not see any connection with fears of extinction.]

Here is the crucial point as far as I can see: our species will go extinct. Nothing can or should stop that anymore than we can or should stop the death of individuals, assuming we want to continue evolving in order for the process of life to continue. The average lifetime of a mammal species is 1-2 Myrs, and we can see from H. erectus that the Homo lineage is, despite the bushy behavior, no exception. Even colonization won't stop that since speciation is an incipient process as soon as population interbreeding drops under an average of 1 breeding/generation. [A somewhat curious result from population genetics, the population sizes are divided out of the problem.]

Life on the other hand may never go extinct as long as it finds a habitable environment. Our one sample is roughly as old as the habitable environment on Earth, indicating a mature biosphere is hardy. I expect our soon-to-come - give or take a Myr - descendants will remember us fondly in the way we remember our great grandparents. "But they lived then, we live now."
Title: Re: Exoplanet Thread
Post by: missinglink on 05/11/2017 08:34 pm
Not a "trick question", just wanted to get an idea how NSF Forum members expect that the relevant organizations -- and the public, which funds them -- will react to detection of life on exoplanets.

Thanks for answers received thus far.
Title: Re: Exoplanet Thread
Post by: dror on 05/11/2017 09:14 pm
My whole interest in space derives from the hope to see that picture.
Sadly, I don't think the reaction will be as immediate or effective as you have suggested. I do hope, though, that it will encourage more reasonable discussions, put some sense in some people who needs it, and allow for a general increase in funding for research.
We must remember, though, that while an exoplanet may save the human race, it will not save the humans on this planet, and won't save this planet from them.
Title: Re: Exoplanet Thread
Post by: Star One on 05/11/2017 09:19 pm
NASA Study Finds Unexpectedly Primitive Atmosphere Around ‘Warm Neptune’

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A study combining observations from NASA’s Hubble and Spitzer space telescopes reveals that the distant planet HAT-P-26b has a primitive atmosphere composed almost entirely of hydrogen and helium. Located about 437 light years away, HAT-P-26b orbits a star roughly twice as old as the sun.

The analysis is one of the most detailed studies to date of a “warm Neptune,” or a planet that is Neptune-sized and close to its star. The researchers determined that HAT-P-26b’s atmosphere is relatively clear of clouds and has a strong water signature, although the planet is not a water world. This is the best measurement of water to date on an exoplanet of this size.

The discovery of an atmosphere with this composition on this exoplanet has implications for how scientists think about the birth and development of planetary systems. Compared to Neptune and Uranus, the planets in our solar system with about the same mass, HAT-P-26b likely formed either closer to its host star or later in the development of its planetary system, or both.


https://www.nasa.gov/feature/goddard/2017/nasa-study-finds-unexpectedly-primitive-atmosphere-around-warm-neptune
Title: Re: Exoplanet Thread
Post by: missinglink on 05/12/2017 02:54 pm
We must remember, though, that while an exoplanet may save the human race, it will not save the humans on this planet, and won't save this planet from them.
True, true...

Life on exoplanets may be detected sooner than we think, if this proposal comes to fruition: https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Solar_Gravity_Lens_Mission/

Just imagine, an habitable planet that doesn't need to be terraformed ... because it's already teeming with lush plant life. Send seed ships with human eggs and sperm, make of it a Second Earth. Ethical to do this to another biosphere? I guess not. Anyway, cost is prohibitive and First Earth gets no return on investment after bankrupting itself to stage the mission. So, probably never happen.
Title: Re: Exoplanet Thread
Post by: gospacex on 05/12/2017 05:50 pm
We must remember, though, that while an exoplanet may save the human race, it will not save the humans on this planet, and won't save this planet from them.
True, true...

Life on exoplanets may be detected sooner than we think, if this proposal comes to fruition: https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Solar_Gravity_Lens_Mission/

Travel to 550 AU to be able to observe a single target? Because steering this telescope would be... difficult, to say the least.

Quote
Just imagine, an habitable planet that doesn't need to be terraformed ... because it's already teeming with lush plant life. Send seed ships with human eggs and sperm, make of it a Second Earth. Ethical to do this to another biosphere? I guess not.

How about founding "bacteria have rights!" movement? It's sickening to think what massacres some people perpetrate daily, using only toothbrushes!
Title: Re: Exoplanet Thread
Post by: Oli on 05/14/2017 03:42 pm
We must remember, though, that while an exoplanet may save the human race, it will not save the humans on this planet, and won't save this planet from them.
True, true...

Life on exoplanets may be detected sooner than we think, if this proposal comes to fruition: https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Solar_Gravity_Lens_Mission/

Travel to 550 AU to be able to observe a single target? Because steering this telescope would be... difficult, to say the least.

If we find a planet with the right atmosphere (i.e. Earth-like), such a mission could certainly be worth it. I'm not aware of any other method that could deliver a 1000x1000px image of an exoplanet other than truly gigantic space telescopes.
Title: Re: Exoplanet Thread
Post by: TakeOff on 05/14/2017 06:45 pm
Just imagine, an habitable planet that doesn't need to be terraformed ... because it's already teeming with lush plant life. Send seed ships with human eggs and sperm, make of it a Second Earth. Ethical to do this to another biosphere? I guess not. Anyway, cost is prohibitive and First Earth gets no return on investment after bankrupting itself to stage the mission. So, probably never happen.

That would be unlikely. Even here on Earth we've had about today's oxygen level only 1/10 of the planet's history. And we might've problems with the microbiomes available before we evolved here. I think we are extremely tightly integrated with Earth as it is now and will have to construct our own environment in other places.
Title: Re: Exoplanet Thread
Post by: TakeOff on 05/14/2017 06:56 pm
Life on exoplanets may be detected sooner than we think, if this proposal comes to fruition: https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Solar_Gravity_Lens_Mission/

Travel to 550 AU to be able to observe a single target? Because steering this telescope would be... difficult, to say the least.
The LISA space laser interferometer is expected to perform an even greater miracle of precision flying. Solar gravity lensing is one of the "resources" that could be taken advantage of from early almost-interstellar flight. Other opportunities might be huge baseline parallax distance measurements and maybe radio interferometry, besides flying by distant objects and studying the interstellar medium. I think that a single object like an interesting exoplanet or the SMBH could be well worth a dedicated observatory.
Title: Re: Exoplanet Thread
Post by: hop on 05/14/2017 07:22 pm
The LISA space laser interferometer is expected to perform an even greater miracle of precision flying.
Precision distance measurement between active spacecraft is not equivalent to precision pointing, so it's a *different* miracle rather than a greater one. But of all the miracles required to make gravitational focus telescope work, pointing probably isn't the biggest.

If we find a planet with the right atmosphere (i.e. Earth-like), such a mission could certainly be worth it. I'm not aware of any other method that could deliver a 1000x1000px image of an exoplanet other than truly gigantic space telescopes.
It's not clear a gravitational focus telescope can actually do this in practice either. See https://arxiv.org/abs/1604.06351

There is already a thread about for the gravitational focus telescope concept:  http://forum.nasaspaceflight.com/index.php?topic=27490.0
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 05/16/2017 08:30 pm
K2-106, a system containing a metal rich planet and a planet of lower density (arXiv) (https://arxiv.org/pdf/1705.04163.pdf)

Quote
The two planets have similar masses, though very different densities. For K2-106b we derive Mp = 7.69 ± 0.82 M⊕, Rp = 1.52 ± 0.16 R⊕, and a high density of 12.0 +4.8 −3.2 g cm−3. For K2-106c, we find 6.79 ± 2.29 M⊕, Rp = 2.59 ± 0.27 R⊕ and a relatively low density of 2.4 +1.6 −1.1 g cm−3.

The 'Fulton Gap' has been proposed to be used to distinguish between 'super-Earths' and 'sub-Neptunes' - with the former having a radius of 1-1.75 R⊕ and the latter one of 1.75–3.5 R⊕. On that definition, this is an interesting system where the super-Earth is more massive than the sub-Neptune!
Title: Re: Exoplanet Thread
Post by: Star One on 05/16/2017 10:10 pm
New 'styrofoam' planet provides tools in search for habitable planets

https://m.phys.org/news/2017-05-styrofoam-planet-tools-habitable-planets.html
Title: Re: Exoplanet Thread
Post by: Star One on 05/25/2017 07:15 pm
Newly Found Exoplanet May Have Ring System Dwarfing Saturn’s

If confirmed, the  world’s rings would be some 200 times wider than Saturn’s and could reveal clues to our solar system’s early history

https://www.scientificamerican.com/article/newly-found-exoplanet-may-have-ring-system-dwarfing-saturn-rsquo-s/
Title: Exoplanet Thread
Post by: Star One on 05/30/2017 11:28 am
Astronomers discover 'super-Earth' planet orbiting nearby star

Quote
Abstract
We report the discovery of a super-Earth orbiting at the inner edge of the habitable zone of the star GJ 625 based on the analysis of the radial-velocity (RV) time series from the HARPS-N spectrograph, consisting in 151 HARPS-N measurements taken over 3.5 yr. GJ 625 b is a planet with a minimum mass M sin i of 2.82 ± 0.51 M⊕ with an orbital period of 14.628 ± 0.013 days at a distance of 0.078 AU of its parent star. The host star is the quiet M2 V star GJ 625, located at 6.5 pc from the Sun. We find the presence of a second radial velocity signal in the range 74-85 days that we relate to stellar rotation after analysing the time series of Ca II H&K and Hα spectroscopic indicators, the variations of the FWHM of the CCF and and the APT2 photometric light curves. We find no evidence linking the short period radial velocity signal to any activity proxy.

https://m.phys.org/news/2017-05-astronomers-super-earth-planet-orbiting-nearby.html
Title: Re: Exoplanet Thread
Post by: hop on 05/30/2017 09:57 pm
More fuel for the M-dwarf tidal locking debate:

On the Spin States of Habitable Zone Exoplanets Around M Dwarfs:The Effect of a Near-Resonant Companion (https://arxiv.org/abs/1705.09685) Alec M. Vinson, Brad M.S. Hansen

Quote
One longstanding problem for the potential habitability of planets within M dwarf systems is their likelihood to be tidally locked in a synchronously rotating spin state. This problem thus far has largely been addressed only by considering two objects: the star and the planet itself. However, many systems have been found to harbor multiple planets, with some in or very near to mean-motion resonances. The presence of a planetary companion near a mean-motion resonance can induce oscillatory variations in the mean-motion of the planet, which we demonstrate can have significant effects on the spin-state of an otherwise synchronously rotating planet. In particular, we find that a planetary companion near a mean-motion resonance can excite the spin states of planets in the habitable zone of small, cool stars, pushing otherwise synchronously rotating planets into higher amplitude librations of the spin state, or even complete circulation resulting in effective stellar days with full surface coverage on the order of years or decades. This increase in illuminated area can have potentially dramatic influences on climate, and thus on habitability. We also find that the resultant spin state can be very sensitive to initial conditions due to the chaotic nature of the spin state at early times within certain regimes. We apply our model to two hypothetical planetary systems inspired by the K00255 and TRAPPIST-1 systems, which both have Earth-sized planets in mean-motion resonances orbiting cool stars.
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 05/31/2017 12:30 am
Astronomers discover 'super-Earth' planet orbiting nearby star

Quote
Abstract
We report the discovery of a super-Earth ... with a minimum mass M sin i of 2.82 ± 0.51 M⊕ ...

https://m.phys.org/news/2017-05-astronomers-super-earth-planet-orbiting-nearby.html

The authors have classified this as a super-Earth on the basis that its mass is between that of Earth and Neptune. I get the impression that most astronomers in the field would consider that definition to be overly-broad, with objects at the upper end of that mass range being referred to as mini-Neptunes instead. The authors do note that the term super-Earth "is also used by astronomers to describe planets bigger than Earth but smaller than the so-called "mini-Neptunes" (with a radius between two to four Earth-radii)."

Is there a confusion between definitions of super-Earths/mini-Neptunes based on mass and those based on the radius? Do astronomers using radial velocity techniques, which gives the mass, differ from their colleagues using transit techniques, which gives the radius?

If this object has the same average density as the Earth, its radius (x sin i) would be 1.41 times that of Earth, which is below the super-Earth/mini-Neptune boundary at 1.75 Earth radii based on the so-called 'Fulton Gap'. However, this is above the boundary based on the transition in the mass-radius relation identified by Chen and Kipping. A borderline case!
Title: Re: Exoplanet Thread
Post by: Star One on 06/02/2017 07:14 pm
Citizen scientists uncover a cold new world near sun

Quote
A new citizen-science tool released earlier this year to help astronomers pinpoint new worlds lurking in the outer reaches of our solar system has already led to a discovery: a brown dwarf a little more than 100 light years away from the Sun. Just six days after the launch of the Backyard Worlds: Planet 9 website in February, four different users alerted the science team to the curious object, whose presence has since been confirmed via an infrared telescope. Details were recently published in the Astrophysical Journal Letters.

Quote
"It's possible that there is a cold world closer than what we believe to be the closest star to the Sun," Faherty said. "Given enough time, I think our volunteers are going help to complete the map of our solar neighborhood."

https://phys.org/news/2017-06-citizen-scientists-uncover-cold-world.amp
Title: Exoplanet Thread
Post by: Star One on 06/05/2017 04:16 pm
Meet KELT-9b, the Hottest Exoplanet Ever Discovered

The exoplanet’s host star blasts it with so much radiation that it will someday evaporate.

Quote
KELT-9b may just be the weirdest exoplanet astronomer Scott Gaudi has ever found. Gaudi, a researcher at The Ohio State University in Columbus, is the lead author of a paper published today in Nature describing the newly discovered hot, gassy exoplanet that is 3 times the size of Jupiter and located 650 light-years away from Earth.

The newly found exoplanet is tidally locked to its host star, meaning one side eternally faces a blast of radiant heat, Gaudi said. The 4300°C temperature of KELT-9b’s “dayside” is only about 1000°C cooler than the surface of our Sun.

If all of KELT-9b were this hot rather than just the dayside, it could be a star. But it still falls short of that classification because it doesn’t heat itself by means of hydrogen fusion. Instead, its heat comes from the intense radiation from its nearby host star, KELT-9.

https://eos.org/articles/meet-kelt-9b-the-hottest-exoplanet-ever-discovered

Weirdly it's in a polar orbit around its star.
Title: Re: Exoplanet Thread
Post by: Star One on 06/08/2017 07:19 pm
Relevant to any exoplanets in orbit around them.

Ultraviolet Insights into Red Dwarf Flares

https://www.centauri-dreams.org/?p=37914
Title: Re: Exoplanet Thread
Post by: Star One on 06/09/2017 04:51 pm
 Planet Formation around TRAPPIST-1

https://www.centauri-dreams.org/?p=37917
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 06/13/2017 02:44 am
Two new massive planets detected around the star HD 27894 (https://phys.org/news/2017-06-massive-planets-star-hd.html) (Phys.org article).
Three planets around HD 27894 (https://arxiv.org/pdf/1706.00509.pdf) (arXiv paper).

Quote
(Abstract)
Aims. Our new program with HARPS aims to detect mean motion resonant planetary systems around stars which were previously reported to have a single bona fide planet, often based only on sparse radial velocity data.
Methods. Archival and new HARPS radial velocities for the K2V star HD 27894 were combined and fitted with a three-planet self-consistent dynamical model. The best-fit orbit was tested for long-term stability.
Results. We find clear evidence that HD 27894 is hosting at least three massive planets. In addition to the already known Jovian planet with a period Pb ≈ 18 days we discover a Saturn-mass planet with Pc ≈ 36 days, likely in a 2:1 mean motion resonance with the first planet, and a cold massive planet (≈ 5.3 MJup) with a period Pd ≈ 5170 days on a moderately eccentric orbit (ed = 0.39).
Conclusions. HD 27894 is hosting a massive, eccentric giant planet orbiting around a tightly packed inner pair of massive planets likely involved in an asymmetric 2:1 mean motion resonance. HD 27894 may be an important milestone for probing planetary formation and evolution scenarios.
Title: Exoplanet Thread
Post by: Star One on 06/13/2017 08:24 am
I still can't help wonder if there are more planets in the large gap.
Title: Re: Exoplanet Thread
Post by: Bynaus on 06/13/2017 08:36 am
Sounds like a 55 Cancri analogue system. A few gas giants on closely packed orbits, with a large, slightly eccentric jovian at ca. 5 AU. The resonance of the innermost two jovians at 55 Cnc is closer to 3:1, and there are more known planets in the 55 Cnc system (a hot super-Earth and a light-weight gas giant in the "gap"), but the similarities are striking (surprisingly, the authors do not mention that in their paper).
Title: Re: Exoplanet Thread
Post by: Star One on 06/13/2017 08:35 pm
New evidence that all stars are born in pairs

Quote
Did our sun have a twin when it was born 4.5 billion years ago?

Almost certainly yes — though not an identical twin. And so did every other sunlike star in the universe, according to a new analysis by a theoretical physicist from the University of California, Berkeley, and a radio astronomer from the Smithsonian Astrophysical Observatory at Harvard University.

Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system. Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars?

Astonomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth’s orbit that collided with our planet and exterminated the dinosaurs. It has never been found.

The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.

“We are saying, yes, there probably was a Nemesis, a long time ago,” said co-author Steven Stahler, a UC Berkeley research astronomer.

“We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.”

http://news.berkeley.edu/2017/06/13/new-evidence-that-all-stars-are-born-in-pairs/
Title: Re: Exoplanet Thread
Post by: Star One on 06/14/2017 07:46 pm
Mistaken brown dwarf is actually two planets orbiting each other

Quote
Finding massive planets is nothing new these days. But finding them orbiting each other instead of orbiting a star is unprecedented. An object initially thought to be a single brown dwarf is actually a pair of giant worlds. It’s not yet clear how this binary system formed, but the discovery may help redefine the line between planets and brown dwarfs – failed stars with tens of times the mass of Jupiter.

This pair of planets is made up of two balls of gas the size of Jupiter but almost four times more massive, separated by some 600 million kilometres, and slowly circling each other once per century or so. The young couple only emits light at infrared wavelengths, with residual heat from their formation, just 10 million years ago.

Observations with the 10-metre Keck II telescope, by a team led by William Best of the University of Hawaii, uncovered the binary system, with the help of adaptive optics that correct for the blurring effects of Earth’s atmosphere.

https://www.newscientist.com/article/2134712-mistaken-brown-dwarf-is-actually-two-planets-orbiting-each-other
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 06/14/2017 11:51 pm
Quote
But are they really planets? Maybe not. In the past, the dividing line between planets and brown dwarfs was generally placed at 14 Jupiter masses, when nuclear fusion of deuterium in the object’s core sets in.

But Latham argues that the best way to distinguish between the two is not by their mass but by how they form: brown dwarfs result from collapsing clouds of gas and dust, while planets form out of a stellar disk.

I think a lot (most, probably) of astronomers who have an opinion would say that these are not planets because they don't orbit a star or stellar remnant. But they're probably not rogue planets either, because it seems unlikely they were ejected from a stellar system as a binary couple. The problem with Latham's suggestion would seem to be how do you tell the difference between a solo brown dwarf and a solo rogue planet? And is there a minimum size, or is every pebble a brown dwarf? (Though this may not matter in practice as it would probably be difficult to detect anything smaller than a gas giant.)
Title: Re: Exoplanet Thread
Post by: clongton on 06/16/2017 12:20 am
... how do you tell the difference between a solo brown dwarf and a solo rogue planet?

I suspect that would be the core temperature. A brown dwarf would be quite a bit warmer than a rogue planet, even a rocky one with a molten core.
Title: Re: Exoplanet Thread
Post by: jebbo on 06/19/2017 09:37 am
An announcement from the Pale Red Dot team is expected at 11am CET:

https://twitter.com/Pale_red_dot/status/876530355523776513

Almost certainly to do with their Barnard's Star campaign (which started a couple of months ago)

--- Tony
Title: Re: Exoplanet Thread
Post by: Alpha_Centauri on 06/19/2017 10:22 am
Sounds like it is just announcing the search rather than any discoveries yet.
Title: Re: Exoplanet Thread
Post by: jebbo on 06/19/2017 10:40 am
Yes.  Search started on June 15th. I got the impression from one of the team that they started looking at Barnard's Star earlier, but apparently not.

They will also be looking at Ross 154 (a flare star).  Home to "Glory Station" in Cherryh's Alliance/Union setting.

--- Tony
Title: Exoplanet Thread
Post by: Star One on 06/19/2017 10:49 am
Sounds like it is just announcing the search rather than any discoveries yet.

I was under the impression there has been an ongoing examination of Barnard's star?

Yes.  Search started on June 15th. I got the impression from one of the team that they started looking at Barnard's Star earlier, but apparently not.

They will also be looking at Ross 154 (a flare star).  Home to "Glory Station" in Cherryh's Alliance/Union setting.

--- Tony

Seems a bit pointless to prioritise a flare star in the search.
Title: Re: Exoplanet Thread
Post by: Alpha_Centauri on 06/19/2017 10:56 am
Proxima is a flare star too, many M dwarfs are.  It's the occupational hazard.

Speaking of which they will also be observing Proxima again for further planets.  Data to be released in real-time.
Title: Re: Exoplanet Thread
Post by: jebbo on 06/19/2017 11:03 am
Seems a bit pointless to prioritise a flare star in the search.

Why? The point of this is to find the nearest planets (i.e. that are the most susceptible to follow-up).

Flare stars (well all M dwarfs really) are a bit problematic for habitability, but - depending on the initial water fraction - it is not ruled out.

--- Tony
Title: Exoplanet Thread
Post by: Star One on 06/19/2017 11:20 am
Seems a bit pointless to prioritise a flare star in the search.

Why? The point of this is to find the nearest planets (i.e. that are the most susceptible to follow-up).

Flare stars (well all M dwarfs really) are a bit problematic for habitability, but - depending on the initial water fraction - it is not ruled out.

--- Tony

I assumed obviously mistakenly by the fact that the OP classed it as a flare star that they were indicating that even amongst M dwarfs it's was very active, otherwise why mention it?
Title: Re: Exoplanet Thread
Post by: jebbo on 06/19/2017 11:55 am
I assumed obviously mistakenly by the fact that the OP classed it as a flare star that they were indicating that even amongst M dwarfs it's was very active, otherwise why mention it?

It is more active than most - it is a UV Ceti type star, with major flares every couple of days or so - which I thought worth mentioning, that's all.

Its age is thought to be <1Gyr so it is a fairly young star, but this age is poorly constrained (gyrochronology!), and M dwarfs become less active with age.

And from a different angle, looking at active flare stars will help us understand the effects of flares.

--- Tony
Title: Exoplanet Thread
Post by: Star One on 06/19/2017 12:02 pm
As a general point are they going to try and tie down Proxima C which I believe is meant to be a larger planet further out than b?
Title: Re: Exoplanet Thread
Post by: jebbo on 06/19/2017 12:25 pm
As a general point are they going to try and tie down Proxima C which I believe is meant to be a larger planet further out than b?

The ESO presser talks about more than one terrestrial sized planet, and there is a linear trend in the Proxima b RV data, so it will help. But whether the campaign will be long enough to confirm a "c" and its period is another question

Edit: there are variations in the 200-300 days and ~40day periods as well. A post is forthcoming on their website.

--- Tony
Title: Re: Exoplanet Thread
Post by: Star One on 06/19/2017 08:34 pm
Article on the same.

Pale Red Dot: Campaign 2

https://www.centauri-dreams.org/?p=37964
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 06/20/2017 06:11 am
Cross-posting to provide links to relevant posts in the Kepler Updates thread:

NASA Releases Kepler Survey Catalog with Hundreds of New Planet Candidates
Here is the briefing material ... [and] the archived video of the press conference:

Quote
... precise measurements of thousands of planets, [reveals] two distinct groups of small planets ... a clean division in the sizes of rocky, Earth-size planets and gaseous planets smaller than Neptune. Few planets were found between those groupings. ...

“We like to think of this study as classifying planets in the same way that biologists identify new species of animals,” said Benjamin Fulton, doctoral candidate at the University of Hawaii in Manoa, and lead author of the second study. “Finding two distinct groups of exoplanets is like discovering mammals and lizards make up distinct branches of a family tree.”

It seems that nature commonly makes rocky planets up to about 75 percent bigger than Earth. For reasons scientists don't yet understand, about half of those planets take on a small amount of hydrogen and helium that dramatically swells their size, allowing them to "jump the gap" and join the population closer to Neptune’s size.

This is what is being called by some (not Benjamin - though he possibly doesn't object! :) ) the Fulton Gap. He gives an explanation in the video as to why it might arise.
Title: Re: Exoplanet Thread
Post by: jebbo on 06/20/2017 10:36 am
This is what is being called by some (not Benjamin - though he possibly doesn't object! :) ) the Fulton Gap. He gives an explanation in the video as to why it might arise.

The original paper is here https://arxiv.org/abs/1703.10375 (https://arxiv.org/abs/1703.10375), and predates the latest DR25 release.

The gap is also known as the "photoevaporation desert" ;-)

--- Tony



Title: Re: Exoplanet Thread
Post by: Alpha_Centauri on 06/20/2017 11:16 am
The photoevaporation desert and the Fulton gap are separate as far as I know. You can see this in the bottom diagram page 12. The photoevaporation desert is the noticeable lack of Neptunes in the very highest insolations, top left. The Fulton gap is the distinct relatively low occurrence gap marked by the crossing point between the two lines denoting the atmospheric loss and gas poor models (the point being the data did not rule out either cause).
Title: Re: Exoplanet Thread
Post by: jebbo on 06/20/2017 12:25 pm
You are quite right! I should have re-read the paper as I clearly misremembered it.  What I should have said was "photoevaporation valley", which has two competing theories on cause.

The joys of getting up at 5:30am with insufficient coffee :-)

--- Tony
Title: Re: Exoplanet Thread
Post by: Alpha_Centauri on 06/20/2017 12:52 pm
I would say you are forgiven, but then again no one is allowed to be wrong on the internet.  :P
Title: Exoplanet Thread
Post by: Star One on 06/20/2017 07:03 pm
A New Classification Scheme for Kepler Planets

https://www.centauri-dreams.org/?p=37972

This seems to make an indirect case for planet nine being as that's meant to be our missing mini-Neptune.
Title: Re: Exoplanet Thread
Post by: Star One on 06/23/2017 08:52 pm
A Partly Cloudy Exoplanet

http://www.skyandtelescope.com/astronomy-news/a-partly-cloudy-exoplanet/
Title: Exoplanet Thread
Post by: Star One on 06/27/2017 10:56 am
Betelgeuse captured by ALMA

Quote
This orange blob shows the nearby star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available.

Betelgeuse is one of the largest stars currently known — with a radius around 1400 times larger than the Sun’s in the millimeter continuum. About 600 light-years away in the constellation of Orion (The Hunter), the red supergiant burns brightly, causing it to have only a short life expectancy. The star is just about eight million years old, but is already on the verge of becoming a supernova. When that happens, the resulting explosion will be visible from Earth, even in broad daylight.

The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface. These features help to explain how the star is shedding gas and dust at tremendous rates (eso0927, eso1121). In this picture, ALMA observes the hot gas of the lower chromosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric. Scientifically, ALMA can help us to understand the extended atmospheres of these hot, blazing stars.
Title: Re: Exoplanet Thread
Post by: CuddlyRocket on 06/27/2017 10:23 pm
Betelgeuse captured by ALMA (link to ESO webpage, including images) (http://www.eso.org/public/unitedkingdom/images/potw1726a/)
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 06/28/2017 09:47 am
Groundbreaking discovery confirms existence of orbiting supermassive black holes

Quote
For the first time ever, astronomers at The University of New Mexico say they've been able to observe and measure the orbital motion between two supermassive black holes hundreds of millions of light years from Earth - a discovery more than a decade in the making.
UNM Department of Physics & Astronomy graduate student Karishma Bansal is the first-author on the paper, 'Constraining the Orbit of the Supermassive Black Hole Binary 0402+379', recently published in The Astrophysical Journal. She, along with UNM Professor Greg Taylor and colleagues at Stanford, the U.S. Naval Observatory and the Gemini Observatory, have been studying the interaction between these black holes for 12 years.
"For a long time, we've been looking into space to try and find a pair of these supermassive black holes orbiting as a result of two galaxies merging," said Taylor. "Even though we've theorized that this should be happening, nobody had ever seen it until now."
In early 2016, an international team of researchers, including a UNM alumnus, working on the LIGO project detected the existence of gravitational waves, confirming Albert Einstein's 100-year-old prediction and astonishing the scientific community. These gravitational waves were the result two stellar mass black holes (~30 solar mass) colliding in space within the Hubble time. Now, thanks to this latest research, scientists will be able to start to understand what leads up to the merger of supermassive black holes that creates ripples in the fabric of space-time and begin to learn more about the evolution of galaxies and the role these black holes play in it.
Using the Very Long Baseline Array (VLBA), a system made up of 10 radio telescopes across the U.S. and operated in Socorro, N.M., researchers have been able to observe several frequencies of radio signals emitted by these supermassive black holes (SMBH). Over time, astronomers have essentially been able to plot their trajectory and confirm them as a visual binary system. In other words, they've observed these black holes in orbit with one another.


Read more at: https://phys.org/news/2017-06-groundbreaking-discovery-orbiting-supermassive-black.html#jCp
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/04/2017 04:12 pm
Probability of CME Impact on Exoplanets Orbiting M Dwarfs and Solar-Like Stars

Quote
Solar coronal mass ejections (CMEs) produce adverse space weather effects at Earth. Planets in the close habitable zone of magnetically active M dwarfs may experience more extreme space weather than at Earth, including frequent CME impacts leading to atmospheric erosion and leaving the surface exposed to extreme flare activity. Similar erosion may occur for hot Jupiters with close orbits around solar-like stars. We have developed a model, Forecasting a CME's Altered Trajectory (ForeCAT), which predicts a CME's deflection. We adapt ForeCAT to simulate CME deflections for the mid-type M dwarf V374 Peg and hot Jupiters with solar-type hosts. V374 Peg's strong magnetic fields can trap CMEs at the M dwarfs's Astrospheric Current Sheet, the location of the minimum in the background magnetic field. Solar-type CMEs behave similarly, but have much smaller deflections and do not get trapped at the Astrospheric Current Sheet. The probability of planetary impact decreases with increasing inclination of the planetary orbit with respect to the Astrospheric Current Sheet - 0.5 to 5 CME impacts per day for M dwarf exoplanets, 0.05 to 0.5 CME impacts per day for solar-type hot Jupiters. We determine the minimum planetary magnetic field necessary to shield a planet's atmosphere from the CME impacts. M dwarf exoplanets require values between tens and hundreds of Gauss. Hot Jupiters around a solar-type star, however, require a more reasonable <30 G. These values exceed the magnitude required to shield a planet from the stellar wind, suggesting CMEs may be the key driver of atmospheric losses.

https://arxiv.org/abs/1605.02683
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/04/2017 07:24 pm
Isotope shift and search for metastable superheavy elements in astrophysical data

Quote
Spectral lines belonging to the short-lifetime heavy radioactive elements up to Es (Z=99) have been found in the spectra of the Przybylski's star. We suggest that these unstable elements may be decay products of a "magic" metastable nucleus belonging to the the island of stability where the nuclei have a magic number of neutrons N=184. The laboratory-produced nuclei have a significantly smaller number of neutrons. To identify spectra of the N=184 isotopes of these nuclei and their neutron-reach superheavy decay products in astrophysical data we calculate the isotope shift which should be added to the laboratory - measured wavelenghs. The results for the isotopic shifts in the strongest optical electromagnetic transitions in No, Lr, Nh, Fl,and Z=120 elements are presented.

https://arxiv.org/abs/1703.04250
Title: Exoplanets And Stars Thread
Post by: Star One on 07/06/2017 07:41 pm
A cosmic barbecue: Researchers spot 60 new 'hot Jupiter' candidates

https://www.eurekalert.org/pub_releases/2017-07/yu-acb070617.php
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 07/07/2017 05:40 am
^^ Paper on arXiv (https://arxiv.org/abs/1706.06602)

Interesting new technique for finding exoplanets, relying on an increase in light flux from a stellar system due to the added light reflected from the exoplanets, rather than a decrease due to a transit. The authors note that their technique needs to be validated by corroboration using doppler measurements, but if it is then it could also be used on other databases of light flux.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/07/2017 06:59 am
^^ Paper on arXiv (https://arxiv.org/abs/1706.06602)

Interesting new technique for finding exoplanets, relying on an increase in light flux from a stellar system due to the added light reflected from the exoplanets, rather than a decrease due to a transit. The authors note that their technique needs to be validated by corroboration using doppler measurements, but if it is then it could also be used on other databases of light flux.
Isn't that paper directly related to the finding of those 60 hot Jupiter candidates covered in the article I posted directly above your post?
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/07/2017 03:50 pm
The low-mass content of the massive young star cluster RCW 38

Quote
RCW 38 is a deeply embedded young (~1 Myr), massive star cluster located at a distance of 1.7 kpc. Twice as dense as the Orion Nebula Cluster, orders of magnitude denser than other nearby star forming regions, and rich in massive stars, RCW 38 is an ideal place to look for potential differences in brown dwarf formation efficiency as a function of environment. We present deep, high resolution adaptive optics data of the central ~0.5x0.5 pc^2 obtained with NACO at the Very Large Telescope. Through comparison with evolutionary models we determine masses and extinction for ~480 candidate members, and derive the first Initial Mass Function (IMF) of the cluster extending into the substellar regime. Representing the IMF as a set of power laws in the form dN/dM~M^(-alpha), we derive the slope alpha = 1.60+-0.13 for the mass range 0.5 - 20 MSun which is shallower than the Salpeter slope, but in agreement with results in several other young massive clusters. At the low-mass side, we find alpha = 0.71+-0.11 for masses between 0.02 and 0.5 MSun, or alpha = 0.81+-0.08 for masses between 0.02 and 1 MSun. Our result is in agreement with the values found in other young star-forming regions, revealing no evidence that a combination of high stellar densities and the presence of numerous massive stars affect the formation efficiency of brown dwarfs and very-low mass stars. We estimate that the Milky Way galaxy contains between 25 and 100 billion brown dwarfs (with masses > 0.03 MSun).

https://arxiv.org/abs/1707.00277
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 07/09/2017 07:57 pm
^^ Paper on arXiv (https://arxiv.org/abs/1706.06602)

Interesting new technique for finding exoplanets, relying on an increase in light flux from a stellar system due to the added light reflected from the exoplanets, rather than a decrease due to a transit. The authors note that their technique needs to be validated by corroboration using doppler measurements, but if it is then it could also be used on other databases of light flux.
Isn't that paper directly related to the finding of those 60 hot Jupiter candidates covered in the article I posted directly above your post?

Yes. Hence the two up-arrows at the beginning of my post, which is forum-speak for 'refers to previous post'.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/09/2017 07:59 pm
^^ Paper on arXiv (https://arxiv.org/abs/1706.06602)

Interesting new technique for finding exoplanets, relying on an increase in light flux from a stellar system due to the added light reflected from the exoplanets, rather than a decrease due to a transit. The authors note that their technique needs to be validated by corroboration using doppler measurements, but if it is then it could also be used on other databases of light flux.
Isn't that paper directly related to the finding of those 60 hot Jupiter candidates covered in the article I posted directly above your post?

Yes. Hence the two up-arrows at the beginning of my post, which is forum-speak for 'refers to previous post'.

I missed those using Tapatalk hence the post. So sorry about that.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 07/11/2017 04:59 am
- 2 up-arrows :) -

No problem. I could've just quoted you or spelt things out - but I was being unnecessarily concise, or lazy, or some combination thereof!
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/12/2017 09:04 am
Hidden Stars May Make Planets Appear Smaller

Quote
In the search for planets similar to our own, an important point of comparison is the planet's density. A low density tells scientists a planet is more likely to be gaseous like Jupiter, and a high density is associated with rocky planets like Earth. But a new study suggests some are less dense than previously thought because of a second, hidden star in their systems.

As telescopes stare at particular patches of sky, they can't always differentiate between one star and two. A system of two closely orbiting stars may appear in images as a single point of light, even from sophisticated observatories such as NASA's Kepler space telescope. This can have significant consequences for determining the sizes of planets that orbit just one of these stars, says a forthcoming study in the Astronomical Journal by Elise Furlan of Caltech/IPAC-NExScI in Pasadena, California, and Steve Howell at NASA's Ames Research Center in California's Silicon Valley.

"Our understanding of how many planets are small like Earth, and how many are big like Jupiter, may change as we gain more information about the stars they orbit," Furlan said. "You really have to know the star well to get a good handle on the properties of its planets."

Some of the most well-studied planets outside our solar system -- or exoplanets -- are known to orbit lone stars. We know Kepler-186f, an Earth-size planet in the habitable zone of its star, orbits a star that has no companion (the habitable zone is the distance at which a rocky planet could support liquid water on its surface). TRAPPIST-1, the ultra-cool dwarf star that is home to seven Earth-size planets, does not have a companion either. That means there is no second star complicating the estimation of the planets' diameters, and therefore their densities.

But other stars have a nearby companion, high-resolution imaging has recently revealed. David Ciardi, chief scientist at the NASA Exoplanet Science Institute (NExScI) at Caltech, led a large-scale effort to follow up on stars that Kepler had studied using a variety of ground-based telescopes. This, combined with other research, has confirmed that many of the stars where Kepler found planets have binary companions. In some cases, the diameters of the planets orbiting these stars were calculated without taking the companion star into consideration. That means estimates for their sizes should be smaller, and their densities higher, than their true values.

Previous studies determined that roughly half of all the sun-like stars in our sun's neighborhood have a companion within 10,000 astronomical units (an astronomical unit is equal to the average distance between the sun and Earth, 93 million miles or 150 million kilometers). Based on this, about 15 percent of stars in the Kepler field could have a bright, close companion -- meaning planets around these stars may be less dense than previously thought.

The Transit Problem for Binaries

When a telescope spots a planet crossing in front of its star -- an event called a "transit" -- astronomers measure the resulting apparent decrease in the star's brightness. The amount of light blocked during a transit depends on the size of the planet -- the bigger the planet, the more light it blocks, and the greater the dimming that is observed. Scientists use this information to determine the radius -- half the diameter -- of the planet.

If there are two stars in the system, the telescope measures the combined light of both stars. But a planet orbiting one of these stars will cause just one of them to dim. So, if you don't know that there is a second star, you will underestimate the size of the planet.

For example, if a telescope observes that a star dims by 5 percent, scientists would determine the transiting planet's size relative to that one star. But if a second star adds its light, the planet must be larger to cause the same amount of dimming.

If the planet orbits the brighter star in a binary pair, most of the light in the system comes from that star anyway, so the second star won't have a big effect on the planet's calculated size. But if the planet orbits the fainter star, the larger, primary star contributes more light to the system, and the correction to the calculated planet radius can be large -- it could double, triple or increase even more. This will affect how the planet's orbital distance is calculated, which could impact whether the planet is found to be in the habitable zone.

If the stars are roughly equal in brightness, the "new" radius of the planet is about 40 percent larger than if the light were assumed to come from a single star. Because density is calculated using the cube of the radius, this would mean a nearly three-fold decrease in density. The impact of this correction is most significant for smaller planets because it means a planet that had once been considered rocky could, in fact, be gaseous.

The New Study

In the new study, Furlan and Howell focused on 50 planets in the Kepler observatory's field of view whose masses and radii were previously estimated. These planets all orbit stars that have stellar companions within about 1,700 astronomical units. For 43 of the 50 planets, previous reports of their sizes did not take into account the contribution of light from a second star. That means a revision to their reported sizes is necessary.

In most cases, the change to the planets' reported sizes would be small. Previous research showed that 24 of the 50 planets orbit the bigger, brighter star in a binary pair. Moreover, Furlan and Howell determined that 11 of these planets would be too large to be planets if they orbited the fainter companion star. So, for 35 of the 50 planets, the published sizes will not change substantially.

But for 15 of the planets, they could not determine whether they orbit the fainter or the brighter star in a binary pair. For five of the 15 planets, the stars in question are of roughly equal brightness, so their densities will decrease substantially regardless of which star they orbit.

This effect of companion stars is important for scientists characterizing planets discovered by Kepler, which has found thousands of exoplanets. It will also be significant for NASA's upcoming Transiting Exoplanet Survey Satellite (TESS) mission, which will look for small planets around nearby, bright stars and small, cool stars.

"In further studies, we want to make sure we are observing the type and size of planet we believe we are," Howell said. "Correct planet sizes and densities are critical for future observations of high-value planets by NASA's James Webb Space Telescope. In the big picture, knowing which planets are small and rocky will help us understand how likely we are to find planets the size of our own elsewhere in the galaxy."

For more information about exoplanets, visit:

https://exoplanets.nasa.gov

https://www.jpl.nasa.gov/news/news.php?release=2017-187&rn=news.xml&rst=6893
Title: Exoplanets And Stars Thread
Post by: Star One on 07/12/2017 01:17 pm
Eight planetary systems found hosting 20 super-Earth & Neptune-mass companions

Quote
A new treasure trove of planets, ranging from worlds with small masses and short orbital periods of less than 15 days to super-Earth-sized planets that can take up to a year to orbit their star, has been discovered by astronomers using the world’s most successful ground-based planet-finding instrument.

The 20 new worlds have been found around eight bright, Sun-like stars by the HARPS (High Accuracy Radial velocity Planet Searcher) Echelle Spectograph instrument, mounted on the 3.6m telescope at the European Southern Observatory in Chile. HARPS, which has discovered around 200 planets since 2003, is are able to measure the velocity of a star’s wobble incurred by the gravity of orbiting planets with the extreme precision of 1 m/s.

Quote
One of the systems observed was a binary system containing the stars HD 20781 and HD 20782. Although planets have been found in binary systems before, it is still uncertain how disruptive the gravitational tides from two stars can be to planet formation, or whether there could be long-term interactions between the two stars and their planets which make them unstable.

This system, however, is packed with planets. Orbiting around the star HD 201781 are two super-Earths with orbits of 5.3 and 13.9 days and two Neptune-mass planets with orbits of 29 and 86 days. The brighter star of the two, HD 20782, also has a Jupiter-sized world in an eccentric 595-day orbit.

Jason Dittman an astronomer at Harvard University was excited by the planets in the study and, in particular, this binary system. “These planets are really interesting because they have these longer orbital periods, and they complement the planets from transit surveys like Kepler. If we want a complete picture of what sort of planets exist in the universe, then discoveries like these are vital to the story,” he says.

Quote
Dittman believes that HARPS and other radial velocity surveys in general don’t get enough credit for the amount of time and dedication that goes into their observations.“Detecting planets with periods that are several years long takes a long time to do because you want to see the planet go around the star a couple of times.”

He continued, “The dedication and forward-thinking to get data on a star for many years is amazing. It’s great to see these long-running radial velocity programs continue to hit pay-dirt and find some longer period, eccentric systems with which to test our theories.”

https://astronomynow.com/2017/07/12/eight-planetary-systems-found-hosting-20-super-earth-neptune-mass-companions/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/12/2017 07:25 pm
Smallest-ever star discovered by astronomers

Quote
The smallest star yet measured has been discovered by a team of astronomers led by the University of Cambridge. With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth.

The star is likely as small as stars can possibly become, as it has just enough mass to enable the fusion of hydrogen nuclei into helium. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place. Hydrogen fusion is also what powers the Sun, and scientists are attempting to replicate it as a powerful energy source here on Earth.

These very small and dim stars are also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds.

The newly-measured star, called EBLM J0555-57Ab, is located about 600 light-years away. It is part of a binary system, and was identified as it passed in front of its much larger companion, a method which is usually used to detect planets, not stars. Details will be published in the journal Astronomy & Astrophysics.

“Our discovery reveals how small stars can be,” said Alexander Boetticher, the lead author of the study, and a Master’s student at Cambridge’s Cavendish Laboratory and Institute of Astronomy. “Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf.”

https://astronomynow.com/2017/07/12/smallest-ever-star-discovered-by-astronomers/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/13/2017 07:20 pm
More to Life Than the Habitable Zone

Quote
The teams, both led by researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., say the behavior of the star in the TRAPPIST-1 system makes it much less likely than generally thought, that planets there could support life.

The TRAPPIST-1 star, a red dwarf, is much fainter and less massive than the Sun. It is rapidly spinning and generates energetic flares of ultraviolet (UV) radiation.

The first team, a pair of CfA theorists, considered many factors that could affect conditions on the surfaces of planets orbiting red dwarfs. For the TRAPPIST-1 system they looked at how temperature could have an impact on ecology and evolution, plus whether ultraviolet radiation from the central star might erode atmospheres around the seven planets surrounding it. These planets are all much closer to the star than the Earth is to the Sun, and three of them are located well within the habitable zone.

"The concept of a habitable zone is based on planets being in orbits where liquid water could exist," said Manasvi Lingam, a Harvard researcher who led the study. "This is only one factor, however, in determining whether a planet is hospitable for life."

Lingam and his co-author, Harvard professor Avi Loeb, found that planets in the TRAPPIST-1 system would be barraged by UV radiation with an intensity far greater than experienced by Earth.

"Because of the onslaught by the star's radiation, our results suggest the atmosphere on planets in the TRAPPIST-1 system would largely be destroyed," said Loeb. "This would hurt the chances of life forming or persisting."

Lingam and Loeb estimate that the chance of complex life existing on any of the three TRAPPIST-1 planets in the habitable zone is less than 1% of that for life existing on Earth.

In a separate study, another research team from the CfA and the University of Massachusetts in Lowell found that the star in TRAPPIST-1 poses another threat to life on planets surrounding it. Like the Sun, the red dwarf in TRAPPIST-1 is sending a stream of particles outwards into space. However, the pressure applied by the wind from TRAPPIST-1's star on its planets is 1,000 to 100,000 times greater than what the solar wind exerts on the Earth.

The authors argue that the star’s magnetic field will connect to the magnetic fields of any planets in orbit around it, allowing particles from the star’s wind to directly flow onto the planet’s atmosphere. If this flow of particles is strong enough, it could strip the planet's atmosphere and perhaps evaporate it entirely.

https://www.cfa.harvard.edu/news/2017-20
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/18/2017 07:40 pm
Why We Need a New Type of SETI Instrument

Quote
The SETI Institute has developed an instrument that, at relatively low cost, could continuously survey the entire night sky for brief laser pulses.  This is completely unlike the optical SETI efforts that have been made in the past, and continue to be made today: experiments that use sensitive photomultiplier detectors, but are limited to one star system at a time.  That’s akin to a radio SETI search able to only monitor a single frequency channel.  Extremely limited.

However, the Institute’s new Laser SETI instrument is not constrained in this way – it can look everywhere simultaneously.  The technology has been prototyped and subjected to preliminary tests, and consists of a robust assembly of straightforward optical and mechanical components.  It can be easily and inexpensively) replicated.

http://www.seti.org/why-we-need-a-new-type-of-seti-instrument
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/19/2017 07:04 pm
“Variable and polarized radio emission from the T6 brown dwarf WISEP J112254.73+255021.5”

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But we do see a lot of complicated variability in the radio emission! What I found to be the most exciting was the measurement shown in the lowest panel of the figure above. It shows the level of circular polarization of the radio waves we get from WISE 1122+25. Almost all astronomical objects emit light that is unpolarized in the circular sense — that is, 0% circular polarization. Radio-emitting brown dwarfs are among the rare objects that can produce high levels of circular polarization. The way we quantify things, circular polarization levels can range between +100%, meaning fully right-handed circular polarization, to –100%, for fully left-handed circular polarization.

What’s neat about the VLA data is that the polarization fraction seems to swing back and forth between the two states. We’ve seen brown dwarfs emit radio bursts with both kinds of handedness, but I’m not aware of any data showing these kind of long-lasting, abrupt transitions. And if you get a bit ambitious in the interpretation, you can imagine that maybe this handedness flips back periodically with the rotation of the brown dwarf. Looking at the different pieces of data, we found some evidence for periodicity at 116 minutes. But the whole observation only spanned 162 minutes, so that’s a very tentative idea — you’d want to see multiple flips back and forth all in sequence to be more confident.

But … if you want to get even more ambitious … You might be able to explain that kind of behavior if this object has a magnetic field that has a major axis that’s very misaligned with the rotation axis. With the right viewing geometry and magnetic polar caps that emitted strongly polarized radiation, you can get curves that look similar to the data.

https://newton.cx/~peter/2017/07/variable-and-polarized-radio-emission-from-the-t6-brown-dwarf-wisep-j112254-73255021-5/
Title: Exoplanets And Stars Thread
Post by: Star One on 07/19/2017 07:53 pm
Astronomers discover Earth-sized exoplanet with very short orbital period

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An international team of astronomers has detected a new Earth-sized exoplanet in an ultra-short period around its parent star. The alien world, designated EPIC 228813918 b, circles its host every four hours and 20 minutes, which makes it the second-shortest orbital period of a planet known to date. The finding was presented in a paper published July 14 on arXiv.org.

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The newly found planet is slightly smaller than Earth (0.89 Earth radii). However, it's extremely massive – its estimated maximum mass is 0.7 Jupiter masses. The exoplanet orbits an M-dwarf star nearly half the size and mass of our sun every 4.3 hours. The planetary system is located some 310 light years away from the Earth.

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The researchers also managed to determine the chemical composition of EPIC 228813918 b. According to them, the planet has an iron core and a silicate mantle. The minimum iron mass fraction was found to be about 0.52, which is greater than that of Earth, Venus or Mars, but smaller than that of Mercury.

https://phys.org/news/2017-07-astronomers-earth-sized-exoplanet-short-orbital.amp
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 07/19/2017 08:26 pm
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However, it's extremely massive – its estimated maximum mass is 0.7 Jupiter masses.

Complete BS (sorry). This is its 3-sigma upper limit mass, based on a full 5 data points... The authors use this figure only to show that the object is in the planetary mass regime (and is not, e.g., a white dwarf). Certainly, one cannot say from that observation alone that "its extremely massive".

Interestingly, they do calculate a minimum density for the planet (>6.4 g/cm3), which is given by the requirement that it orbits its star outside the Roche limit, and from this a minimum iron core fraction of 0.45 (higher than the Earth but lower than Mercury - but again, remember this is a lower limit).
Title: Re: Exoplanets And Stars Thread
Post by: as58 on 07/19/2017 09:12 pm
Complete BS (sorry). This is its 3-sigma upper limit mass, based on a full 5 data points... The authors use this figure only to show that the object is in the planetary mass regime (and is not, e.g., a white dwarf). Certainly, one cannot say from that observation alone that "its extremely massive".

That's some impressive misreporting by phys.org. The mass limit is not mentioned in the abstract, so they must've read the paper. Alas, apparently without understanding much.

edit: Some nitpicking, mass upper limit is based only on the two Keck/HIRES observations, which are much more accurate than Subaru/IRCS radial velocities.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 07/20/2017 03:20 am
Astronomers discover Earth-sized exoplanet with very short orbital period

From the arXiv paper (https://arxiv.org/abs/1707.04549):

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For a stellar radius of 0.44 R and a radius ratio of ≈ 0.02, we derive a planetary radius of around 1.0 R⊕. For such a planet, we consider a very conservative upper-limit to the mass to be 3 M⊕ (Seager et al. 2007 predict a mass of around 2.7 M⊕ for a 1 R⊕ planet composed of solid iron).
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/26/2017 06:33 pm
Gamma-ray burst captured in unprecedented detail

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Data from multiple telescopes used to address long-standing questions about the universe's most powerful explosions

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Gamma-ray bursts are among the most energetic and explosive events in the universe. They are also short-lived, lasting from a few milliseconds to about a minute. This has made it tough for astronomers to observe a gamma-ray burst in detail. Using a wide array of ground- and space-based telescope observations, astronomers constructed one of the most detailed descriptions of a gamma-ray burst to date.

https://www.sciencedaily.com/releases/2017/07/170726132110.htm
Title: Re: Exoplanets And Stars Thread
Post by: hop on 07/26/2017 07:46 pm
Oops. It seems some "validated" planets are more valid than others
Disproval of the validated planets K2-78b, K2-82b, and K2-92b (https://arxiv.org/abs/1707.08007) (accepted for publication in A&A)
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Transiting super-Earths orbiting bright stars in short orbital periods are interesting targets for the study of planetary atmospheres. While selecting super-Earths suitable for further characterization from the ground among a list of confirmed and validated exoplanets detected by K2, we found some suspicious cases that led to us re-assessing the nature of the detected transiting signal. We did a photometric analysis of the K2 light curves and centroid motions of the photometric barycenters. Our study shows that the validated planets K2-78b, K2-82b, and K2-92b are actually not planets but background eclipsing binaries. The eclipsing binaries are inside the Kepler photometric aperture, but outside the ground-based high resolution images used for validation. We advise extreme care on the validation of candidate planets discovered by space missions. It is important that all the assumptions in the validation process are carefully checked. An independent confirmation is mandatory in order to avoid wasting valuable resources on further characterization of non-existent targets.
Title: Exoplanets And Stars Thread
Post by: Star One on 07/26/2017 09:02 pm
Oops. It seems some "validated" planets are more valid than others
Disproval of the validated planets K2-78b, K2-82b, and K2-92b (https://arxiv.org/abs/1707.08007) (accepted for publication in A&A)
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Transiting super-Earths orbiting bright stars in short orbital periods are interesting targets for the study of planetary atmospheres. While selecting super-Earths suitable for further characterization from the ground among a list of confirmed and validated exoplanets detected by K2, we found some suspicious cases that led to us re-assessing the nature of the detected transiting signal. We did a photometric analysis of the K2 light curves and centroid motions of the photometric barycenters. Our study shows that the validated planets K2-78b, K2-82b, and K2-92b are actually not planets but background eclipsing binaries. The eclipsing binaries are inside the Kepler photometric aperture, but outside the ground-based high resolution images used for validation. We advise extreme care on the validation of candidate planets discovered by space missions. It is important that all the assumptions in the validation process are carefully checked. An independent confirmation is mandatory in order to avoid wasting valuable resources on further characterization of non-existent targets.

Isn't this paper rather stating the obvious and the last Kepler main mission release was done off the back of follow up ground observations.
Title: Re: Exoplanets And Stars Thread
Post by: hop on 07/27/2017 03:13 am
Isn't this paper rather stating the obvious and the last Kepler main mission release was done off the back of follow up ground observations.
No. Relevant sentence from the abstract
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The eclipsing binaries are inside the Kepler photometric aperture, but outside the ground-based high resolution images used for validation.
In other words, there was strong evidence of the EBs in the Kepler data, but the team that "validated" the planets didn't do the checks that would have caught them, and also didn't detect the EBs in their ground based follow up because they were outside the FOV.

From the discussion
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Our result shows that, though planet validation techniques are useful tools, great care needs to be taken to correctly validate candidate planets discovered by space missions. Crossfield et al. (2016) made a sound statistical study and a careful and detailed ground-based characterization of the targets, including high angular resolution imaging, but they failed to look for possible contaminants a few arcseconds away from the targets. In the cases mentioned above, the contaminants were too far away to be included in the field of view of the high resolution image and they were not considered further in the analysis.  The reliability of a statistical study is only as good as the understanding of the contamination sources. Here we show i) that validation methods applied to these targets by Crossfield et al.  (2016) underestimate the impact of background contaminants and consequently, ii) the planet likelihood estimates are not representative of the true nature of the candidates in these cases.

We insist that this is not the result of a failure of the design of the validation procedure, but the result of an incorrect assessment of the impact on the photometry of neighbouring sources. Our results can be used to improve the performance of planet validation techniques.
(emphasis in the original)

FWIW, the original paper reporting these ex-planets is https://arxiv.org/abs/1607.05263
Title: Re: Exoplanets And Stars Thread
Post by: Alpha_Centauri on 07/27/2017 03:45 am
Super-Pandora? Candidate Neptune-sized exomoon potentially orbiting Superjovian Kepler-1625b.


HEK VI: On the Dearth of Galilean Analogs in Kepler and the Exomoon Candidate Kepler-1625b I
https://arxiv.org/pdf/1707.08563.pdf
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Finally, we have briefly highlighted our identification of an exomoon candidate in the Kepler-1625 system, for which we have secured a follow-up observation with HST. This candidate has passed a thorough preliminary inspection, but we emphasize again our position that the Kepler data are insufficient to make a conclusive statement about the existence of this moon. Only after the HST observation is made [October 2017] should any claim about this moon’s existence be given much credence.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 07:09 am
So what do they want them to do go through all the data from Kepler again, that will take years and no doubt cost a fair bit of money?
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 07/27/2017 07:49 am
So what do they want them to do go through all the data from Kepler again, that will take years and no doubt cost a fair bit of money?

Who is they and them? The Kepler data are freely available.

Regarding the "super-Pandora", this is an exiting - potential - find. Such systems might be rare (just as Hot Jupiters turned out to be rare), but it would be no surprise that the first exomoon was indeed a somewhat exotic Jovian/Neptunian binary. Looking forward to the results coming from the upcoming HST observation.
Title: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 08:12 am
So what do they want them to do go through all the data from Kepler again, that will take years and no doubt cost a fair bit of money?

Who is they and them? The Kepler data are freely available.

Regarding the "super-Pandora", this is an exiting - potential - find. Such systems might be rare (just as Hot Jupiters turned out to be rare), but it would be no surprise that the first exomoon was indeed a somewhat exotic Jovian/Neptunian binary. Looking forward to the results coming from the upcoming HST observation.

The Kepler team, I assumed it would be obvious that's who I was referring to? After all how many groups are going to have the time and money to go through all that public data, money doesn't grow on trees these days.
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 07/27/2017 11:20 am
So what do they want them to do go through all the data from Kepler again, that will take years and no doubt cost a fair bit of money?

Who is they and them? The Kepler data are freely available.

Regarding the "super-Pandora", this is an exiting - potential - find. Such systems might be rare (just as Hot Jupiters turned out to be rare), but it would be no surprise that the first exomoon was indeed a somewhat exotic Jovian/Neptunian binary. Looking forward to the results coming from the upcoming HST observation.

The Kepler team, I assumed it would be obvious that's who I was referring to? After all how many groups are going to have the time and money to go through all that public data, money doesn't grow on trees these days.

There is no expectation towards the core Kepler team involved here. Its also not like there is a "final word" on the Kepler data, either. Different researchers have been looking at the same data for many years now and the way these data have been reduced (how we go from raw data to exoplanet parameters) has been improved time and again, and will no doubt continue to happen in the future to some extent.

Looking for exomoons is also a completely different thing - and thus requires a different approach and data processing pipline (see the linked paper) - than to look for exoplanets. The funding for this kind of projects using publicly available data depends on the funding background of the individual researcher. In this case, Kipping is both a tenured professor at a university and probably has some external project funding from NSF, NASA or other sources.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 11:28 am
So what do they want them to do go through all the data from Kepler again, that will take years and no doubt cost a fair bit of money?

Who is they and them? The Kepler data are freely available.

Regarding the "super-Pandora", this is an exiting - potential - find. Such systems might be rare (just as Hot Jupiters turned out to be rare), but it would be no surprise that the first exomoon was indeed a somewhat exotic Jovian/Neptunian binary. Looking forward to the results coming from the upcoming HST observation.

The Kepler team, I assumed it would be obvious that's who I was referring to? After all how many groups are going to have the time and money to go through all that public data, money doesn't grow on trees these days.

There is no expectation towards the core Kepler team involved here. Its also not like there is a "final word" on the Kepler data, either. Different researchers have been looking at the same data for many years now and the way these data have been reduced (how we go from raw data to exoplanet parameters) has been improved time and again, and will no doubt continue to happen in the future to some extent.

Looking for exomoons is also a completely different thing - and thus requires a different approach and data processing pipline (see the linked paper) - than to look for exoplanets. The funding for this kind of projects using publicly available data depends on the funding background of the individual researcher. In this case, Kipping is both a tenured professor at a university and probably has some external project funding from NSF, NASA or other sources.

The only way I can see any group reanalysing all the Kepler data is if someone comes up with an algorithm to do all the heavy lifting.
Title: Re: Exoplanets And Stars Thread
Post by: Alpha_Centauri on 07/27/2017 11:31 am
Lead author on the exomoon paper explains their rationale for publishing now;

https://blogs.scientificamerican.com/observations/are-astronomers-on-the-verge-of-finding-an-exomoon/
Title: Re: Exoplanets And Stars Thread
Post by: LouScheffer on 07/27/2017 01:53 pm
Oops. It seems some "validated" planets are more valid than others
Disproval of the validated planets K2-78b, K2-82b, and K2-92b (https://arxiv.org/abs/1707.08007) (accepted for publication in A&A)
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[...] Our study shows that the validated planets K2-78b, K2-82b, and K2-92b are actually not planets but background eclipsing binaries. The eclipsing binaries are inside the Kepler photometric aperture, but outside the ground-based high resolution images used for validation. We advise extreme care on the validation of candidate planets discovered by space missions. It is important that all the assumptions in the validation process are carefully checked. An independent confirmation is mandatory in order to avoid wasting valuable resources on further characterization of non-existent targets.

OK, they found that 3 out of 104 were really false positives, where only one was expected (statistically), then figured out why so it can be avoided in the future.  Clearly valuable, but it does not change the overall exo-planet statistics much.  If you are trying to do any sort of planetary census, there are much bigger sources of error.  If you are zooming in on one particular star, though, it's worth double checking.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 04:15 pm
Posting this mostly because of the seemingly bizarre attitude of the IAU to the naming of this comet, which has resulted in the team who discovered it not being credited.

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Never heard of ASAS-SN? It’s an automated sky survey hunting for supernovae in both hemispheres, with instruments based at Haleakala in Hawaii and Cerro Tololo in Chile. Though the survey targets supernovae, it does on occasion pick up other interesting astronomical phenomena as well. This is the first comet discovery for the ASAS-SN team, as they join the ranks of PanSTARRS, LINEAR and other prolific robotic comet hunters.

Evoking the very name “ASAS-SN” seems to have sparked a minor controversy as well, as the International Astronomical Union (IAU) declined to name the comet after the survey, listing it simply as “C/2017 O1”. Word is, “ASAS-SN” was to close to the word “Assassin” (this is actually controversial?) For our money, we’ll simply keep referring to the comet as “O1 ASAS-SN” as a recognition of the team’s hard work and their terrific discovery.

https://www.universetoday.com/136564/new-comet-c2017-o1-asas-sn-takes-earth-surprise/
Title: Re: Exoplanets And Stars Thread
Post by: hop on 07/27/2017 05:18 pm
OK, they found that 3 out of 104 were really false positives, where only one was expected (statistically), then figured out why so it can be avoided in the future.
It's not clear to me Cabrera et al looked at all 104 of those planets, they were looking at specific planets for followup.
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Clearly valuable, but it does not change the overall exo-planet statistics much.  If you are trying to do any sort of planetary census, there are much bigger sources of error.  If you are zooming in on one particular star, though, it's worth double checking.
It's also important to note that these are K2 planets. K2 data is open to all: Discoveries are made by whoever publishes first and aren't validated by the Kepler team, so this doesn't necessarily have any implication for the main Kepler catalog. My impression is the normal Kepler validation process includes tests that would have flagged these.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 05:42 pm
OK, they found that 3 out of 104 were really false positives, where only one was expected (statistically), then figured out why so it can be avoided in the future.
It's not clear to me Cabrera et al looked at all 104 of those planets, they were looking at specific planets for followup.
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Clearly valuable, but it does not change the overall exo-planet statistics much.  If you are trying to do any sort of planetary census, there are much bigger sources of error.  If you are zooming in on one particular star, though, it's worth double checking.
It's also important to note that these are K2 planets. K2 data is open to all: Discoveries are made by whoever publishes first and aren't validated by the Kepler team, so this doesn't necessarily have any implication for the main Kepler catalog. My impression is the normal Kepler validation process includes tests that would have flagged these.

Thanks for clarifying this was for K2, as that makes my posts up thread irrelevant here.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 06:50 pm
A Tale of Three Stellar Cities

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Using new observations from ESO’s VLT Survey Telescope, astronomers have discovered three different populations of young stars within the Orion Nebula Cluster. This unexpected discovery adds very valuable new insights for the understanding of how such clusters form. It suggests that star formation might proceed in bursts, where each burst occurs on a much faster time-scale than previously thought.

OmegaCAM — the wide-field optical camera on ESO’s VLT Survey Telescope (VST) — has captured the spectacular Orion Nebula and its associated cluster of young stars in great detail, producing a beautiful new image. This object is one of the closest stellar nurseries for both low and high-mass stars, at a distance of about 1350 light-years [1].

But this is more than just a pretty picture. A team led by ESO astronomer Giacomo Beccari has used these data of unparallelled quality to precisely measure the brightness and colours of all the stars in the Orion Nebula Cluster. These measurements allowed the astronomers to determine the mass and ages of the stars. To their surprise, the data revealed three different sequences of potentially different ages.

“Looking at the data for the first time was one of those ‘Wow!’ moments that happen only once or twice in an astronomer's lifetime,” says Beccari, lead ­author of the paper presenting the results. “The incredible quality of the OmegaCAM images revealed without any doubt that we were seeing three distinct populations of stars in the central parts of Orion.”

Monika Petr-Gotzens, co-author and also based at ESO Garching, continues, “This is an important result. What we are witnessing is that the stars of a cluster at the beginning of their lives didn’t form altogether simultaneously. This may mean that our understanding of how stars form in clusters needs to be modified.”

The astronomers looked carefully at the possibility that instead of indicating different ages, the different brightnesses and colours of some of the stars were due to hidden companion stars, which would make the stars appear brighter and redder than they really were. But this idea would imply quite unusual properties of the pairs, which have never before been observed. Other measurements of the stars, such as their rotation speeds and spectra, also indicated that they must have different ages [2].

“Although we cannot yet formally disprove the possibility that these stars are binaries, it seems much more natural to accept that what we see are three generations of stars that formed in succession, within less than three million years,” concludes Beccari.

The new results strongly suggest that star formation in the Orion Nebula Cluster is proceeding in bursts, and more quickly than had been previously thought.

http://www.eso.org/public/news/eso1723/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/27/2017 08:16 pm
BBC article with additional reporting on the story.

Signal may be from first 'exomoon'

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But Dr Kipping said this is not the best way to gauge the potential detection.
He told BBC News: "We're excited about it... statistically, formally, it's a very high probability. But do we really trust the statistics? That's something unquantifiable. Until we get the measurements from Hubble, it may as well be 50-50 in my mind."
The candidate moon is known as Kepler-1625b I and is observed around a star that lies some 4,000 light-years from Earth. On account of its large size, team members have dubbed it a "Nep-moon".
A current theory of planetary formation suggests such an object is unlikely to have formed in place with its Jupiter-mass planet, but would instead be an object captured by the gravity of the planet later on in the evolution of this planetary system.
The researchers could find no predictions of a Neptune-sized moon in the literature, but Dr Kipping notes that nothing in physics prevents one.
A handful of possible candidates have come to light in the past, but none as yet has been confirmed.
"I'd say it's the best [candidate] we've had," Dr Kipping told me.
"Almost every time we hit a candidate, and it passes our tests, we invent more tests until it finally dies - until it fails one of the tests... in this case we've applied everything we've ever done and it's passed all of those tests. On the other hand, we only have three events."

http://www.bbc.co.uk/news/science-environment-40741545
Title: Re: Exoplanets And Stars Thread
Post by: hop on 07/28/2017 07:31 am
Here's Alex Teachey and David Kipping (authors of the exomoon paper) talking about the result, and why they ended up going public now

https://www.youtube.com/watch?v=8V9QHn5oHMs
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 07/28/2017 09:53 am
Good news for James Cameron as if you can get moons the size of Neptune there's nothing to say you couldn't get moons the size of Earth around a super sized gas giant. So you would end up with a system as seen in the film like Avatar if you had more than one of them.
Title: Re: Exoplanets And Stars Thread
Post by: rubtest on 07/28/2017 10:06 am
Was there any search for tiny moons around the biggest MOONS in the solar systems like Titan , Ganymede ?
I am almost sure it is gravitational an impossibility because of the Jupiter / Saturn strong gravitational fields.
Title: Exoplanets And Stars Thread
Post by: Star One on 07/28/2017 06:52 pm
New Nature article about the possible exomoon discovery with some useful quotes.

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Jean Schneider, an exomoon hunter at the Paris Observatory, says that the authors were right to make this candidate public. Now, he says, “other people can re-analyse the Kepler data for Kepler-1625 b and make their own opinion”.

Astronomer David Bennett at the University of Notre Dame in Indiana agrees. “I don’t consider it to be terribly controversial to put a paper on the arXiv before it is peer reviewed,” he says. “It is often the case that the journal doesn’t really find the best person to review the paper,” he adds. “If it is posted on arXiv.org, then you might get much more useful comments from a real expert who wasn’t picked by the journal to review the paper.”

http://www.nature.com/news/why-astronomers-reluctantly-announced-a-possible-exomoon-discovery-1.22377
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/01/2017 02:36 am
Four new short-period giant planets discovered (https://phys.org/news/2017-07-short-period-giant-planets.html)

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Astronomers have detected four new giant exoplanets as part of the Hungarian-made Automated Telescope Network-South (HATSouth) exoplanet survey. The newly found alien worlds are about the size of Jupiter, but less massive. They transit moderately bright stars and have short orbital periods.

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According to the paper, HATS-45b is the largest and most massive exoworld of all the newly discovered exoplanets. It has a radius of about 1.29 Jupiter radii and is 30 percent less massive than our solar system's biggest planet. It orbits its parent star every 4.19 days.

HATS-46b has the longest orbital period and is the least massive of the newly found quartet. It has only 17 percent of the mass of Jupiter, however a radius of approximately 0.9 Jupiter radii. It takes this planet 4.74 days to fully circle its host.

HATS-43b and HATS-44b are similar in radius—1.18 and 1.07 Jupiter radii respectively. HATS-43b has a mass of 0.26 Jupiter masses, while HATS-44b is about two times more massive—0.56 Jupiter masses. The shortest orbital period among the four newly identified planets belongs to HATS-44b, which orbits its star in just 2.74 days. When it comes to HATS-43b, it takes it approximately 4.39 days to circle its parent star.
Title: Re: Exoplanets And Stars Thread
Post by: Phil Stooke on 08/01/2017 02:57 am
"Was there any search for tiny moons around the biggest MOONS in the solar systems like Titan , Ganymede ?"

I can't give a source at the moment, but I believe there have been searches for rings and moons around the larger moons of Saturn, at least.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/01/2017 04:40 pm

Exomoons: Rare in Inner Stellar Systems?

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With all this in mind, every paper that comes out of HEK gets my attention. Kipping (Columbia University), working with graduate student Alex Teachey and citizen scientist Allan Schmitt, has now produced a paper that takes a significant step as the investigation proceeds. We have no detection yet — more about that in a moment — but we do have a broader result showing that exomoons are unusual in the inner regions of the systems surveyed.

Kipping and Teachey looked at 284 viable moon-hosting Kepler planetary candidates to search for moons around planets from Earth to Jupiter in size and distances from their stars of 0.1 to 1 AU. This finding seems to be getting less attention in the press than it deserves, so let’s dig into the paper on it:

Our results place new upper limits on the exomoon population for planets orbiting within about 1 AU of their host star, upper limits that are remarkably low. We have also analyzed subsets of the ensemble to test the effect of various data cuts, and we have identified the regime in which the OSE model presented in Heller (2014) breaks down, which we call the “Callisto Effect” — beyond 20 planetary radii, discrepancies appear in the results.

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Back to the paper:

Our analysis suggests that exomoons may be quite rare around planets at small semi-major axes, a finding that supports theoretical work suggesting moons may be lost as planets migrate inward. On the other hand, if the dearth of exomoons can be read as a reliable indicator of migration, our results suggest a large fraction of the planets in the ensemble have migrated to their present location.

And that is a pointer to which we need to pay attention. Is a lack of exomoons a marker for planetary migration? If further analysis determines that it is, then we’ve found an extremely handy tool for studying the formation history of other stellar systems

https://www.centauri-dreams.org/?p=38214
Title: Exoplanets And Stars Thread
Post by: Star One on 08/03/2017 08:32 am
Hubble detects exoplanet with glowing water atmosphere

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Scientists have discovered the strongest evidence to date for a stratosphere on a planet outside our solar system, or exoplanet. A stratosphere is a layer of atmosphere in which temperature increases with higher altitudes.

“This result is exciting because it shows that a common trait of most of the atmospheres in our solar system — a warm stratosphere — also can be found in exoplanet atmospheres,” said Mark Marley, study co-author based at NASA’s Ames Research Center in California’s Silicon Valley. “We can now compare processes in exoplanet atmospheres with the same processes that happen under different sets of conditions in our own solar system.”

Reporting in the journal Nature, scientists used data from NASA’s Hubble Space Telescope to study WASP-121b, a type of exoplanet called a “hot Jupiter.” Its mass is 1.2 times that of Jupiter, and its radius is about 1.9 times Jupiter’s — making it puffier. But while Jupiter revolves around our sun once every 12 years, WASP-121b has an orbital period of just 1.3 days. This exoplanet is so close to its star that if it got any closer, the star’s gravity would start ripping it apart. It also means that the top of the planet’s atmosphere is heated to a blazing 4,600 degrees Fahrenheit (2,500 degrees Celsius), hot enough to boil some metals. The WASP-121 system is estimated to be about 900 light-years from Earth — a long way, but close by galactic standards.

https://astronomynow.com/2017/08/02/hubble-detects-exoplanet-with-glowing-water-atmosphere/

Astronomers discover ‘heavy metal’ supernova rocking out

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Following the recent discovery of one of these “superluminous supernovas”, a team of astronomers led by Matt Nicholl from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., has uncovered vital clues about where some of these extraordinary objects come from.

Cambridge University’s Gaia Science Alerts team discovered this supernova, dubbed SN 2017egm, on May 23, 2017 with the European Space Agency’s Gaia satellite. A team led by Subo Dong of the Kavli Institute for Astronomy and Astrophysics at Peking University used the Nordic Optical Telescope to identify it as a superluminous supernova.

SN 2017egm is located in a spiral galaxy about 420 million light years from Earth, making it about three times closer than any other superluminous supernova previously seen. Dong realized that the galaxy was very surprising, as virtually all known superluminous supernovas have been found in dwarf galaxies that are much smaller than spiral galaxies like the Milky Way.

Building on this discovery, the CfA team found that SN 2017egm’s host galaxy has a high concentration of elements heavier than hydrogen and helium, which astronomers call “metals”. This is the first clear evidence for a metal-rich birthplace for a superluminous supernova. The dwarf galaxies that usually host superluminous supernovas are known to have a low metal content, which was thought to be an essential ingredient for making these explosions.

“Superluminous supernovas were already the rock stars of the supernova world,” said Nicholl. “We now know that some of them like heavy metal, so to speak, and explode in galaxies like our own Milky Way.”

https://astronomynow.com/2017/08/02/astronomers-discover-heavy-metal-supernova-rocking-out/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/03/2017 07:33 pm
Disintegrating Rocky Exoplanets

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We discuss a new class of exoplanets that appear to be emitting a tail of dusty effluents. These disintegrating planets are found close to their host stars and have very hot, and likely molten, surfaces. The properties of the dust should provide a direct probe of the constituent material of these rocky bodies.

https://arxiv.org/abs/1708.00633
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/03/2017 07:53 pm
Gravity Waves Detected In Sun's Interior Reveal Rapidly Rotating Core

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Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun’s core is rotating four times faster than its surface.

http://m.esa.int/Our_Activities/Space_Science/Space_Science/Gravity_waves_detected_in_Sun_s_interior_reveal_rapidly_rotating_core
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/04/2017 08:10 pm
Bad News For Proxima b: An Earth-Like Atmosphere Might Not Survive There

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So it’s not all bad news, but it doesn’t inspire a lot of confidence either. Unless Proxima b is a volcanically-active planet and subject to a lot of cometary impacts, it is not likely be temperate, water-bearing world. Most likely, its climate will be analogous to Mars – cold, dry, and with water existing mostly in the form of ice. And as for indigenous life emerging there, that’s not too likely either.

These and other recent studies have painted a rather bleak picture about the habitability of red dwarf star systems. Given that these are the most common types of stars in the known Universe, the statistical likelihood of finding a habitable planet beyond our Solar System appears to be dropping. Not exactly good news at all for those hoping that life will be found out there within their lifetimes!

But it is important to remember that what we can say definitely at this point about extra-solar planets is limited. In the coming years and decades, next-generation missions – like the James Webb Space Telescope (JWST) and the Transiting Exoplanet Survey Satellite (TESS) –  are sure to paint a more detailed picture. In the meantime, there’s still plenty of stars in the Universe, even if most of them are extremely far away!

https://www.universetoday.com/136641/bad-news-proxima-b-earth-like-atmosphere-might-not-survive/amp/
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/09/2017 02:56 pm
Four Earth-sized planets detected orbiting the nearest sun-like star (https://news.ucsc.edu/2017/08/tau-ceti-planets.html)

(http://i.imgur.com/Lyin3Sf.jpg)

(http://i.imgur.com/hIXxlWJ.png)

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A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water.

The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second.

"We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.

According to lead author Fabo Feng of the University of Hertfordshire, UK, the researchers are getting tantalizingly close to the 10-centimeter-per-second limit required for detecting Earth analogs. "Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth's habitability through comparison with these analogs," Feng said. "We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals."

The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.

The same team also investigated tau Ceti four years ago in 2013, when coauthor Mikko Tuomi of the University of Hertfordshire led an effort in developing data analysis techniques and using the star as a benchmark case. "We came up with an ingenious way of telling the difference between signals caused by planets and those caused by star's activity. We realized that we could see how star's activity differed at different wavelengths and use that information to separate this activity from signals of planets," Tuomi said.

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals the team had identified in 2013 as planets. "But no matter how we look at the star, there seem to be at least four rocky planets orbiting it," Tuomi said. "We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface. This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system."

Color difference makes a difference: four planet candidates around tau Ceti (https://arxiv.org/abs/1708.02051)

If confirmed, there would seem to be decent room for an Earth mass planet in the middle of the habitable zone which wouldn't currently be detectable.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/09/2017 06:49 pm
Is Tau Ceti more sunlike than either of the Alpha Centauri stars then?
Title: Re: Exoplanets And Stars Thread
Post by: Bob Shaw on 08/09/2017 07:12 pm
Have any planets been *really* detected around Bernard's Star? It would be rather nice!
Title: Re: Exoplanets And Stars Thread
Post by: zubenelgenubi on 08/09/2017 07:37 pm
Re: nearest sun-like star

Star                      Mass, in solar masses   Spectral Type (Sun = G2V)

Alpha Centauri A    1.10                           G2V

Alpha Centauri B    0.91                            K1V

Sirius A                 2.02                            A1V

Epsilon Eridani       0.82                            K2V

Procyon A             1.50                            F5V-IV

Epsilon Indi A        0.76                             K5V

Tau Ceti                0.78                            G8V


They may be applying data in a partly-subjective manner to claim "nearest sun-like star:"
distance, Main Sequence star near 1 solar mass, not part of a binary or multiple star system, etc.
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 08/09/2017 07:38 pm
It is noteworthy that if the planetary system is aligned with the debris disk (which seems very likely), the true masses of the four planets are about double their minimum masses. So the inner two planets would be large super-Earths, whereas the outer two would be mini-Neptunes.

@StarOne: I think of these three stars, Alpha Cen A is most sun-like. It is also a G2V type, is only 10% more massive and has a similar rotation period. Then Tau Ceti, then Alpha Cen B.

@Bob Shaw: the planets that van de Kamp thought were there (in the 1960ies) do not exist, this we know for sure. Otherwise, we only have upper limits on mass/distance (<7.5 Earth masses in the habitable zone, e.g.). The Red Dots (https://twitter.com/RedDotsSpace) project is bound to find out!
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/09/2017 08:23 pm
It is noteworthy that if the planetary system is aligned with the debris disk (which seems very likely), the true masses of the four planets are about double their minimum masses. So the inner two planets would be large super-Earths, whereas the outer two would be mini-Neptunes.

@StarOne: I think of these three stars, Alpha Cen A is most sun-like. It is also a G2V type, is only 10% more massive and has a similar rotation period. Then Tau Ceti, then Alpha Cen B.

@Bob Shaw: the planets that van de Kamp thought were there (in the 1960ies) do not exist, this we know for sure. Otherwise, we only have upper limits on mass/distance (<7.5 Earth masses in the habitable zone, e.g.). The Red Dots (https://twitter.com/RedDotsSpace) project is bound to find out!

Thank you. Could you direct me towards any articles or papers speculating on the origins of the debris disk around Tau Ceti?
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 08/09/2017 08:34 pm
It is noteworthy that if the planetary system is aligned with the debris disk (which seems very likely), the true masses of the four planets are about double their minimum masses. So the inner two planets would be large super-Earths, whereas the outer two would be mini-Neptunes.

@StarOne: I think of these three stars, Alpha Cen A is most sun-like. It is also a G2V type, is only 10% more massive and has a similar rotation period. Then Tau Ceti, then Alpha Cen B.

@Bob Shaw: the planets that van de Kamp thought were there (in the 1960ies) do not exist, this we know for sure. Otherwise, we only have upper limits on mass/distance (<7.5 Earth masses in the habitable zone, e.g.). The Red Dots (https://twitter.com/RedDotsSpace) project is bound to find out!

Thank you. Could you direct me towards any articles or papers speculating on the origins of the debris disk around Tau Ceti?

Look here for a recent overview of the situation (although still with the originally proposed 5 planets):
http://adsabs.harvard.edu/abs/2015csss...18..783L

The classic paper on the Tau Ceti debris disk is probably this one: http://adsabs.harvard.edu/abs/2004MNRAS.351L..54G
Title: Exoplanets And Stars Thread
Post by: Star One on 08/09/2017 08:38 pm
It is noteworthy that if the planetary system is aligned with the debris disk (which seems very likely), the true masses of the four planets are about double their minimum masses. So the inner two planets would be large super-Earths, whereas the outer two would be mini-Neptunes.

@StarOne: I think of these three stars, Alpha Cen A is most sun-like. It is also a G2V type, is only 10% more massive and has a similar rotation period. Then Tau Ceti, then Alpha Cen B.

@Bob Shaw: the planets that van de Kamp thought were there (in the 1960ies) do not exist, this we know for sure. Otherwise, we only have upper limits on mass/distance (<7.5 Earth masses in the habitable zone, e.g.). The Red Dots (https://twitter.com/RedDotsSpace) project is bound to find out!

Thank you. Could you direct me towards any articles or papers speculating on the origins of the debris disk around Tau Ceti?

Look here for a recent overview of the situation (although still with the originally proposed 5 planets):
http://adsabs.harvard.edu/abs/2015csss...18..783L

The classic paper on the Tau Ceti debris disk is probably this one: http://adsabs.harvard.edu/abs/2004MNRAS.351L..54G

Thanks that second paper sounds interesting.

Seems likely any life that might have got going would probably have been 'bombed' out of existence by that debris disk.
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/09/2017 08:55 pm
It's only necessary for unicellular photosynthetic organisms to survive long enough that there's enough oxygen in the atmosphere to detect. I'm not convinced that oceans full of unicellular life would be completely wiped out by asteroid and comet impacts.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/09/2017 09:03 pm
It's only necessary for unicellular photosynthetic organisms to survive long enough that there's enough oxygen in the atmosphere to detect. I'm not convinced that oceans full of unicellular life would be completely wiped out by asteroid and comet impacts.

But with that kind of disc isn't there a danger that the bombardment would be so heavy that it would leave the surfaces of these planets something like IO.
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/09/2017 09:18 pm
It's "only" estimated to be 10x the frequency as on Earth, which might be an issue for complex life, but shouldn't be an issue for unicellular life. I would also guess that super Earths are more likely to have denser atmospheres than Earth, which would help to mitigate the higher frequency of impacts to an extent.

Cometary impacts might also be beneficial for life, bringing water and organics.

Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 08/09/2017 09:42 pm
Note that its just that the mass of the debris disk is estimated to be about 10x the mass of the Kuiper belt. To go from there to a 10x higher bombardment rate on the planets in the system is quite problematic. After all, the Earth is primarily bombarded from the asteroid belt, not the Kuiper belt! Bombardment rates on planets primarily depend on the efficiency of delivery of small bodies to planet-crossing orbits (e.g. through resonances and non-gravitational forces), which in turn depends on the system planetary architecture. We know nothing of planets in the outer part (>1 AU) of the Tau Ceti system. Without a detailed simulation, talk of relative bombardment rates and its implications for life on these planets is pure fantasy.
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/09/2017 10:34 pm
Good point, but I still think it's reasonable to assume a higher frequency of impacts. Still, even if that does have an impact on complex life, it's still possible that unicellular photosynthetic life could recover quickly and it might be possible to detect evidence of (or indeed lack of) oxygen in exoplanet atmospheres in the future.



Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/10/2017 07:27 pm
Hint of relativity effects in stars orbiting centre of galaxy

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A new analysis of data from ESO’s Very Large Telescope and other telescopes suggests that the orbits of stars around the supermassive black hole at the centre of the Milky Way may show the subtle effects predicted by Einstein’s general theory of relativity. There are hints that the orbit of the star S2 is deviating slightly from the path calculated using classical physics. This tantalising result is a prelude to much more precise measurements and tests of relativity that will be made using the GRAVITY instrument as star S2 passes very close to the black hole in 2018.

https://astronomynow.com/2017/08/10/hint-of-relativity-effects-in-stars-orbiting-centre-of-galaxy/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/11/2017 09:24 pm
Two bright, variable sources with unusual light curves discovered by ASAS-SN

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As part of an ongoing effort by ASAS-SN project (Shappee et al. 2014; Kochanek et al. 2017) to characterize and catalog all bright variable stars, we have discovered two bright, variable sources with unusual light curves---ASASSN-V J033455.88-053957.9 (mean V~13.0) and ASASSN-V J211014.40-242105.3 (mean V~14.5).

ASASSN-V J033455.88-053957.9 raises slowly in brightness by ~0.5 mag in ~1,800 days (ASAS-SN Sky Patrol light curve; data points in red are likely affected by artifacts and should not be taken into consideration). A spectrum of this source was obtained by the RAVE survey (Kunder et al. 2017) giving values of T_eff=3660 K and log g =5.1 cm/s^2, fairly typical for an early-type M-dwarf. The 2MASS colors for this source (J-H=0.59 and H-Ks=0.10) also correspond to M1/M2 spectral type M-dwarf (West et al. 2011). ASASSN-V J033455.88-053957.9 appears in a number of X-ray catalogs, including the Swift X-ray point source catalogue (Evans et al. 2014). ASAS-SN light curve for ASASSN-V J033455.88-053957.9 is very unusual for an M-dwarf, and we encourage further observations of this source.

ASASSN-V J211014.40-242105.3 (ASAS-SN Sky Patrol light curve) is mostly flat at around V~14.5 mag, with a big drop in brightness of at least ~2 mag, lasting at least 150 days. This source was spectroscopically classified as a cataclysmic variable, with Balmer and HeII 4686A emission lines (Kilkenny et al. 2015). We conclude that ASASSN-V J211014.40-242105.3 is most likely a cataclysmic variable (CV) of the VY Scl type.

We thank Las Cumbres Observatory and its staff for their continued support of ASAS-SN. ASAS-SN is funded in part by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University, NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the Chinese Academy of Sciences South America Center for Astronomy (CASSACA).

http://www.astronomerstelegram.org/?read=10634
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/12/2017 07:45 pm
TRAPPIST-1 is Older Than Our Solar System

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If we want to know more about whether life could survive on a planet outside our solar system, it's important to know the age of its star. Young stars have frequent releases of high-energy radiation called flares that can zap their planets' surfaces. If the planets are newly formed, their orbits may also be unstable. On the other hand, planets orbiting older stars have survived the spate of youthful flares, but have also been exposed to the ravages of stellar radiation for a longer period of time.

Scientists now have a good estimate for the age of one of the most intriguing planetary systems discovered to date -- TRAPPIST-1, a system of seven Earth-size worlds orbiting an ultra-cool dwarf star about 40 light-years away. Researchers say in a new study that the TRAPPIST-1 star is quite old: between 5.4 and 9.8 billion years. This is up to twice as old as our own solar system, which formed some 4.5 billion years ago.

The seven wonders of TRAPPIST-1 were revealed earlier this year in a NASA news conference, using a combination of results from the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, NASA's Spitzer Space Telescope, and other ground-based telescopes. Three of the TRAPPIST-1 planets reside in the star's "habitable zone," the orbital distance where a rocky planet with an atmosphere could have liquid water on its surface. All seven planets are likely tidally locked to their star, each with a perpetual dayside and nightside.

At the time of its discovery, scientists believed the TRAPPIST-1 system had to be at least 500 million years old, since it takes stars of TRAPPIST-1's low mass (roughly 8 percent that of the Sun) roughly that long to contract to its minimum size, just a bit larger than the planet Jupiter. However, even this lower age limit was uncertain; in theory, the star could be almost as old as the universe itself. Are the orbits of this compact system of planets stable? Might life have enough time to evolve on any of these worlds?

"Our results really help constrain the evolution of the TRAPPIST-1 system, because the system has to have persisted for billions of years. This means the planets had to evolve together, otherwise the system would have fallen apart long ago," said Adam Burgasser, an astronomer at the University of California, San Diego, and the paper's first author. Burgasser teamed up with Eric Mamajek, deputy program scientist for NASA's Exoplanet Exploration Program based at NASA's Jet Propulsion Laboratory, Pasadena, California, to calculate TRAPPIST-1's age. Their results will be published in The Astrophysical Journal.

It is unclear what this older age means for the planets' habitability. On the one hand, older stars flare less than younger stars, and Burgasser and Mamajek confirmed that TRAPPIST-1 is relatively quiet compared to other ultra-cool dwarf stars. On the other hand, since the planets are so close to the star, they have soaked up billions of years of high-energy radiation, which could have boiled off atmospheres and large amounts of water. In fact, the equivalent of an Earth ocean may have evaporated from each TRAPPIST-1 planet except for the two most distant from the host star: planets g and h. In our own solar system, Mars is an example of a planet that likely had liquid water on its surface in the past, but lost most of its water and atmosphere to the Sun's high-energy radiation over billions of years.

However, old age does not necessarily mean that a planet's atmosphere has been eroded. Given that the TRAPPIST-1 planets have lower densities than Earth, it is possible that large reservoirs of volatile molecules such as water could produce thick atmospheres that would shield the planetary surfaces from harmful radiation. A thick atmosphere could also help redistribute heat to the dark sides of these tidally locked planets, increasing habitable real estate. But this could also backfire in a "runaway greenhouse" process, in which the atmosphere becomes so thick the planet surface overheats - as on Venus.

"If there is life on these planets, I would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years," Burgasser said.

Fortunately, low-mass stars like TRAPPIST-1 have temperatures and brightnesses that remain relatively constant over trillions of years, punctuated by occasional magnetic flaring events. The lifetimes of tiny stars like TRAPPIST-1 are predicted to be much, much longer than the 13.7 billion-year age of the universe (the Sun, by comparison, has an expected lifetime of about 10 billion years).

"Stars much more massive than the Sun consume their fuel quickly, brightening over millions of years and exploding as supernovae," Mamajek said. "But TRAPPIST-1 is like a slow-burning candle that will shine for about 900 times longer than the current age of the universe."

Some of the clues Burgasser and Mamajek used to measure the age of TRAPPIST-1 included how fast the star is moving in its orbit around the Milky Way (speedier stars tend to be older), its atmosphere's chemical composition, and how many flares TRAPPIST-1 had during observational periods. These variables all pointed to a star that is substantially older than our Sun.

Future observations with NASA's Hubble Space Telescope and upcoming James Webb Space Telescope may reveal whether these planets have atmospheres, and whether such atmospheres are like Earth's.

"These new results provide useful context for future observations of the TRAPPIST-1 planets, which could give us great insight into how planetary atmospheres form and evolve, and persist or not," said Tiffany Kataria, exoplanet scientist at JPL, who was not involved in the study.

Future observations with Spitzer could help scientists sharpen their estimates of the TRAPPIST-1 planets' densities, which would inform their understanding of their compositions.

For more information about TRAPPIST-1, visit:

https://exoplanets.nasa.gov/trappist1
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/12/2017 07:53 pm
Here's the relevant paper.

On the Age of the TRAPPIST-1 System

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The nearby (d = 12 pc) M8 dwarf star TRAPPIST-1 (2MASS J23062928-0502285) hosts a compact system of at least seven exoplanets with sizes similar to Earth. Given its importance for testing planet formation and evolution theories, and for assessing the prospects for habitability among Earth-size exoplanets orbiting the most common type of star in the Galaxy, we present a comprehensive assessment of the age of this system. We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6±2.2 Gyr. The star's color-magnitude position is consistent with it being slightly metal-rich ([Fe/H] ≃ +0.06), in line with its previously reported near-infrared spectroscopic metallicity; and it has a radius (R = 0.121±0.003 R⊙) that is larger by 8-14% compared to solar-metallicity evolutionary models. We discuss some implications of the old age of this system with regard to the stability and habitability of its planets.

https://arxiv.org/abs/1706.02018
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 08/14/2017 06:34 am
A planetary system around near-by YZ Ceti.

https://arxiv.org/abs/1708.03336

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The HARPS search for southern extra-solar planets XLII. A system of Earth-mass planets around the nearby M dwarf YZ Cet

Exoplanet surveys have shown that systems with multiple low-mass planets on compact orbits are common. Except for few cases, however, the masses of these planets are generally unknown. At the very end of the main sequence, host stars have the lowest mass and hence offer the largest reflect motion for a given planet. In that context, we monitored the low-mass (0.13Msun) M dwarf YZ Cet (GJ 54.1, HIP 5643) intensively and obtained both radial velocities and stellar-activity indicators derived from both spectroscopy and photometry. We find strong evidence that it is orbited by at least three planets in compact orbits (P=1.97, 3.06, 4.66 days), with the inner two near a 2:3 mean-motion resonance. The minimum masses are comparable to that of Earth (Msini=0.75+-0.13, 0.98+-0.14, and 1.14+-0.17 Mearth) and also the lowest masses measured by radial velocity so far. We note the possibility for an even lower-mass, fourth planet with Msini=0.472+-0.096 Mearth at P=1.04 days. An n-body dynamical model is used to put further constraints on the system parameters. At 3.6 parsecs, YZ Cet is the nearest multi-planet system detected to date.

Cool factoid: YZ Ceti is a star currently located only 1.6 LY from Tau Ceti.
Title: Exoplanets And Stars Thread
Post by: Star One on 08/15/2017 07:32 pm
Tidally locked exoplanets may be more common than previously thought

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Many exoplanets to be found by coming high-powered telescopes will probably be tidally locked — with one side permanently facing their host star — according to new research by astronomer Rory Barnes of the University of Washington.

Barnes, a UW assistant professor of astronomy and astrobiology, arrived at the finding by questioning the long-held assumption that only those stars that are much smaller and dimmer than the sun could host orbiting planets that were in synchronous orbit, or tidally locked, as the moon is with the Earth. His paper, “Tidal Locking of Habitable Exoplanets,” has been accepted for publication by the journal Celestial Mechanics and Dynamical Astronomy.

Quote
Barnes writes: “These results suggest that the process of tidal locking is a major factor in the evolution of most of the potentially habitable exoplanets to be discovered in the near future.”

Being tidally locked was once thought to lead to such extremes of climate as to eliminate any possibility of life, but astronomers have since reasoned that the presence of an atmosphere with winds blowing across a planet’s surface could mitigate these effects and allow for moderate climates and life.

Barnes said he also considered the planets that will likely be discovered by NASA’s next planet-hunting satellite, the Transiting Exoplanet Survey Satellite or TESS, and found that every potentially habitable planet it will detect will likely be tidally locked.

http://www.washington.edu/news/2017/08/14/tidally-locked-exoplanets-may-be-more-common-than-previously-thought/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/16/2017 08:00 pm
Tuning Up RV: A Test Case at Tau Ceti

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And so on. The lesson is clear enough: We have to be extremely careful when interpreting signals below 1 meter per second, the range in which we’ll need to identify Earth-class planets.

But the value of radial velocity is unquestioned. Unlike the transit technique, we don’t have to rely on a fortuitous line-up between a distant planetary system and the Earth — we can therefore extend it to all bright stars of interest. Feng and colleagues think we will be able to use new high precision spectrometers along with these emerging statistical and noise models to find a true Earth analog in the coming decade. Thus this work on Tau Ceti, modeling wavelength-dependent noise, becomes a test case of a new noise model framework that can help us filter background noise out of RV observations.

https://www.centauri-dreams.org/?p=38293
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/17/2017 03:07 pm
We may have caught supernova debris slamming into neighboring stars

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In a new paper, a large team of researchers notes that a couple of recent supernovae have shown an unexpected excess of blue light. They then go on to describe the supernova SN 2017cbv, which became visible in March of this year. In this case, the supernova was spotted only a day after the explosion took place. Follow-up observations over the next six weeks allowed the team to build up a detailed record of the aftermath of the supernova (called a light curve). This record was then compared to what we'd expect from a typical type-Ia supernova.

Compared to a standard type-Ia supernova, SN 2017cbv showed an excess of light at all wavelengths, including the blue and UV regions. This was mostly pronounced during the first week after the explosion, as the light ramped up toward its peak. At the peak, there was an excess in redder wavelengths than you'd see in a typical type-Ia supernova.

What could cause this? To find out, the team modified a model of type-Ia supernovae to include a shockwave running into a nearby star. The modified model fits the data well and suggests that somewhere between five and 15 percent of the light during the peak came from the shockwave hitting a nearby star.

The model, however, suggests that the companion star was nearly 40 million miles from the white dwarf (which is a bit closer than Mercury is to our Sun). That's right on the far edge of where you'd expect the companion star to be if the two were close enough to share material. However, the authors point out that this model assumes that they're looking at the event-companion with an ideal viewing angle. If the angle is off, it would look dimmer, which would make the companion star appear to be farther away.

https://arstechnica.com/science/2017/08/we-may-have-caught-supernova-debris-slamming-into-neighboring-stars/
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 08/18/2017 02:15 am
One of the commenters identified the paper on arXiv: Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor (https://arxiv.org/abs/1706.08990).

Unfortunately, they don't say what happened to the companion star. :(
Title: Re: Exoplanets And Stars Thread
Post by: Kesarion on 08/18/2017 08:13 am
How is it determined if an exoplanet is really orbiting a star?  In other words, there could be some some lost asteroid sized object millions of light years in between us and the star.  Maybe there is an Oort Cloud object eclipsing a star?  It would just periodically move in front of a star to dim the light


As far as I can remember, in order for a Kepler candidate to be confirmed as an exoplanet, they must observe 3 periodic eclipses and also be confirmed by a ground based telescope. That might have changed since 2013 though.
Title: Re: Exoplanets And Stars Thread
Post by: gospacex on 08/18/2017 08:36 am
How is it determined if an exoplanet is really orbiting a star?  In other words, there could be some some lost asteroid sized object millions of light years in between us and the star.

Asteroid-sized object would not be detectable - the dip is too small.

Quote
  Maybe there is an Oort Cloud object eclipsing a star?  It would just periodically move in front of a star to dim the light

In this case, "periodically" would mean "every 500k years".
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/18/2017 06:35 pm
Dynamics of a Probable Earth-mass Planet in the GJ 832 System

Quote
The stability of planetary orbits around the GJ 832 star system, which contains inner (GJ 832c) and outer (GJ 832b) planets, is investigated numerically and a detailed phase-space analysis is performed. Special attention is given to the existence of stable orbits for a planet less than 15 M ⊕ that is injected between the inner and outer planets. Thus, numerical simulations are performed for three and four bodies in elliptical orbits (or circular for special cases) by using a large number of initial conditions that cover the selected phase-spaces of the planet's orbital parameters. The results presented in the phase-space maps for GJ 832c indicate the least deviation of eccentricity from its nominal value, which is then used to determine its inclination regime relative to the star–outer planet plane. Also, the injected planet is found to display stable orbital configurations for at least one billion years. Then, the radial velocity curves based on the signature from the Keplerian motion are generated for the injected planets with masses 1 M ⊕ to 15 M ⊕ in order to estimate their semimajor axes and mass limits. The synthetic RV signal suggests that an additional planet of mass ≤15 M ⊕ with a dynamically stable configuration may be residing between 0.25 and 2.0 au from the star. We have provided an estimated number of RV observations for the additional planet that is required for further observational verification.

http://iopscience.iop.org/article/10.3847/1538-4357/aa80e2/meta
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/18/2017 07:04 pm
Habitable Planet Reality Check: Tau Ceti

http://www.drewexmachina.com/2017/08/18/habitable-planet-reality-check-tau-ceti/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/18/2017 07:23 pm
Scientists improve brown dwarf weather forecasts

Quote
To make sense of the ups and downs of brightness, scientists had to rethink their assumptions about what was going on in the brown dwarf atmospheres. The best model to explain the variations involves large waves, propagating through the atmosphere with different periods. These waves would make the cloud structures rotate with different speeds in different bands.

University of Arizona researcher Theodora Karalidi used a supercomputer and a new computer algorithm to create maps of how clouds travel on these brown dwarfs.

“When the peaks of the two waves are offset, over the course of the day there are two points of maximum brightness,” Karalidi said. “When the waves are in sync, you get one large peak, making the brown dwarf twice as bright as with a single wave.”

The results explain the puzzling behavior and brightness changes that researchers previously saw. The next step is to try to better understand what causes the waves that drive cloud behavior.

https://astronomynow.com/2017/08/17/scientists-improve-brown-dwarf-weather-forecasts/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/18/2017 09:50 pm
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 08/18/2017 11:16 pm
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Proxima Centauri (and its planet) is the 'C' component of the Alpha Centauri system. However, neither Alpha Centauri A or B are known to have planets. Nor does Barnard's Star (4th nearest), Wolf 359 (5th), Sirius (6th), Gliese 65 A and B (7th and 8th), Ross 154 (9th) and Ross 248 (10th)!

(Disregarding brown and white dwarfs - though none of those closer than Ross 248 are known to have planets either.)
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/18/2017 11:19 pm
Only in as far as most stars are believed to have planets. Most of the nearest stars (https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs) to 16.3 ly* still don't even have candidate planets yet.

*To 21 ly (http://www.johnstonsarchive.net/astro/nearstar.html), as Wikipedia doesn't seem to have a list of stars (https://en.wikipedia.org/wiki/Category:Lists_of_stars) from 16.3 - 20 ly.
Title: Re: Exoplanets And Stars Thread
Post by: redliox on 08/19/2017 05:30 am
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Only in as far as most stars are believed to have planets. Most of the nearest stars (https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs) to 16.3 ly* still don't even have candidate planets yet.

*To 21 ly (http://www.johnstonsarchive.net/astro/nearstar.html), as Wikipedia doesn't seem to have a list of stars (https://en.wikipedia.org/wiki/Category:Lists_of_stars) from 16.3 - 20 ly.

Although fortunately we have TESS and the JWST coming up, I'd like to see an effort to catalog specifically our neighboring stars.  I don't expect it to be easy, but it would be worth it.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/19/2017 08:14 am
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Proxima Centauri (and its planet) is the 'C' component of the Alpha Centauri system. However, neither Alpha Centauri A or B are known to have planets. Nor does Barnard's Star (4th nearest), Wolf 359 (5th), Sirius (6th), Gliese 65 A and B (7th and 8th), Ross 154 (9th) and Ross 248 (10th)!

(Disregarding brown and white dwarfs - though none of those closer than Ross 248 are known to have planets either.)

Aren't Pale Red Dot now studying all our local red dwarfs for planets?
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/19/2017 11:38 am
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Only in as far as most stars are believed to have planets. Most of the nearest stars (https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs) to 16.3 ly* still don't even have candidate planets yet.

*To 21 ly (http://www.johnstonsarchive.net/astro/nearstar.html), as Wikipedia doesn't seem to have a list of stars (https://en.wikipedia.org/wiki/Category:Lists_of_stars) from 16.3 - 20 ly.

Although fortunately we have TESS and the JWST coming up, I'd like to see an effort to catalog specifically our neighboring stars.  I don't expect it to be easy, but it would be worth it.


ESPRESSO (https://www.eso.org/public/teles-instr/paranal-observatory/vlt/vlt-instr/espresso/) should also be helpful with that. It's an order of magnitude more sensitive than HARPS and should be online this year (if not already, it saw first light nearly a year ago).
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/19/2017 02:24 pm
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Proxima Centauri (and its planet) is the 'C' component of the Alpha Centauri system. However, neither Alpha Centauri A or B are known to have planets. Nor does Barnard's Star (4th nearest), Wolf 359 (5th), Sirius (6th), Gliese 65 A and B (7th and 8th), Ross 154 (9th) and Ross 248 (10th)!

(Disregarding brown and white dwarfs - though none of those closer than Ross 248 are known to have planets either.)

Aren't Pale Red Dot now studying all our local red dwarfs for planets?

AFAIK just Proxima Centauri, Barnard's Star, and Ross 154.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/19/2017 02:25 pm
Does this mean now that with the exception of Alpha Centauri all the stars near to Sol are believed to have planets?
Proxima Centauri (and its planet) is the 'C' component of the Alpha Centauri system. However, neither Alpha Centauri A or B are known to have planets. Nor does Barnard's Star (4th nearest), Wolf 359 (5th), Sirius (6th), Gliese 65 A and B (7th and 8th), Ross 154 (9th) and Ross 248 (10th)!

(Disregarding brown and white dwarfs - though none of those closer than Ross 248 are known to have planets either.)

Aren't Pale Red Dot now studying all our local red dwarfs for planets?

AFAIK just Proxima Centauri, Barnard's Star, and Ross 154.

Out of interest what was the criteria for choosing those three out of all the red dwarfs near Sol?
Title: Re: Exoplanets And Stars Thread
Post by: Alpha_Centauri on 08/19/2017 02:42 pm
Because they are visible from La Silla at this time of year and are bright enough for high-res spectroscopy.
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 08/19/2017 03:21 pm
There is a candidate for a Super Earth (https://arxiv.org/abs/1702.03571) around Lalande 21185, the 6th closest main sequence star / 4th closest star system (it's missing from CuddlyRocket's list).
Title: Re: Exoplanets And Stars Thread
Post by: Hungry4info3 on 08/19/2017 05:33 pm
Aren't Pale Red Dot now studying all our local red dwarfs for planets?
AFAIK just Proxima Centauri, Barnard's Star, and Ross 154.
Out of interest what was the criteria for choosing those three out of all the red dwarfs near Sol?
Because they are visible from La Silla at this time of year and are bright enough for high-res spectroscopy.
To add to that, there has been a shift in in strategy in recent years for radial velocity surveys away from "Sample numerous stars a few times each" to "Sample a few stars numerous times each." The first one easily catches your intermediate- and long-period giant planets, but to get down to low-mass planets, you have to really drill a star to get enough data to overcome statistical noise. Detecting low-mass planets in the solar neighborhood is now finally feasible, so rather than observing all the local M dwarfs in the sky, we're focusing on hitting a few nearby, bright systems.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/19/2017 05:45 pm
Aren't Pale Red Dot now studying all our local red dwarfs for planets?
AFAIK just Proxima Centauri, Barnard's Star, and Ross 154.
Out of interest what was the criteria for choosing those three out of all the red dwarfs near Sol?
Because they are visible from La Silla at this time of year and are bright enough for high-res spectroscopy.
To add to that, there has been a shift in in strategy in recent years for radial velocity surveys away from "Sample numerous stars a few times each" to "Sample a few stars numerous times each." The first one easily catches your intermediate- and long-period giant planets, but to get down to low-mass planets, you have to really drill a star to get enough data to overcome statistical noise. Detecting low-mass planets in the solar neighborhood is now finally feasible, so rather than observing all the local M dwarfs in the sky, we're focusing on hitting a few nearby, bright systems.

Thank you all. I am constantly amazed that we are able to make such fine measurements of objects so far, it almost seems remarkable.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 08/20/2017 08:27 pm
There is a candidate for a Super Earth (https://arxiv.org/abs/1702.03571) around Lalande 21185, the 6th closest main sequence star / 4th closest star system (it's missing from CuddlyRocket's list).

I didn't include Lalande 21185 in my list because I was listing those stars not known to have a planet and this star has a pretty solid candidate. But then I forgot to adjust the ordinal numbering (Sirius should be the 7th nearest etc.)!  :-[
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 08/22/2017 07:50 am
Dynamics of a Probable Earth-mass Planet in the GJ 832 System

Quote
The stability of planetary orbits around the GJ 832 star system, which contains inner (GJ 832c) and outer (GJ 832b) planets, is investigated numerically and a detailed phase-space analysis is performed. Special attention is given to the existence of stable orbits for a planet less than 15 M ⊕ that is injected between the inner and outer planets. Thus, numerical simulations are performed for three and four bodies in elliptical orbits (or circular for special cases) by using a large number of initial conditions that cover the selected phase-spaces of the planet's orbital parameters. The results presented in the phase-space maps for GJ 832c indicate the least deviation of eccentricity from its nominal value, which is then used to determine its inclination regime relative to the star–outer planet plane. Also, the injected planet is found to display stable orbital configurations for at least one billion years. Then, the radial velocity curves based on the signature from the Keplerian motion are generated for the injected planets with masses 1 M ⊕ to 15 M ⊕ in order to estimate their semimajor axes and mass limits. The synthetic RV signal suggests that an additional planet of mass ≤15 M ⊕ with a dynamically stable configuration may be residing between 0.25 and 2.0 au from the star. We have provided an estimated number of RV observations for the additional planet that is required for further observational verification.

http://iopscience.iop.org/article/10.3847/1538-4357/aa80e2/meta

I have to say I find that article a bit weird. Its not like they have detected anything, not even that there is a hint in the data for the presence of an additional planet. All they have is "if there is a planet here, its orbit would be stable". Oh well - a super-Earth way inside Mercury would also be on a stable orbit, but that doesn't mean there is one. But still, you have news sites like this one (https://www.universetoday.com/136837/another-nearby-red-dwarf-star-system-another-possible-exoplanet-discovered/) running with headlines suggesting a planet has been found...
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/22/2017 04:30 pm
New Findings on Brown Dwarf Atmospheres

Interesting tidbit from this article.

Quote
I often think of brown dwarfs in terms of the planets that might form around them, and the question of whether even these small ‘failed stars’ may be capable of sustaining life. Have a look, for example, at Luhman 16AB, two brown dwarfs in the Sun’s immediate neighborhood. There are some indications of a planet here which, if it were ever confirmed, would make it the second closest known exoplanet to the Earth, at least for now. We can rule out planets of Neptune mass or greater with a period of between one and two years, but future Hubble observations, already approved for August of next year, may tell us more.

https://www.centauri-dreams.org/?p=38327
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/22/2017 07:12 pm
On reflection this seems more appropriate in this area.

Likely Transiting Exocomets Detected by Kepler

Quote
We present the first good evidence for exocomet transits of a host star in continuum light in data from the Kepler mission. The Kepler star in question, KIC 3542116, is of spectral type F2V and is quite bright at Kp=10. The transits have a distinct asymmetric shape with a steeper ingress and slower egress that can be ascribed to objects with a trailing dust tail passing over the stellar disk. There are three deeper transits with depths of ≃0.1% that last for about a day, and three that are several times more shallow and of shorter duration. The transits were found via an exhaustive visual search of the entire Kepler photometric data set, which we describe in some detail. We review the methods we use to validate the Kepler data showing the comet transits, and rule out instrumental artifacts as sources of the signals. We fit the transits with a simple dust-tail model, and find that a transverse comet speed of ∼35-50 km s−1 and a minimum amount of dust present in the tail of ∼1016 g are required to explain the larger transits. For a dust replenishment time of ∼10 days, and a comet lifetime of only ∼300 days, this implies a total cometary mass of ≳3×1017 g, or about the mass of Halley's comet. We also discuss the number of comets and orbital geometry that would be necessary to explain the six transits detected over the four years of Kepler prime-field observations. Finally, we also report the discovery of a single comet-shaped transit in KIC 11084727 with very similar transit and host-

https://arxiv.org/abs/1708.06069
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/24/2017 12:34 am
The META detections. Somewhat before my time so I had never heard of these before. Useful links in the description to further reading as well.

https://youtu.be/xKrrkHk5Sts
Title: Exoplanets And Stars Thread
Post by: Star One on 08/24/2017 09:59 pm
The CGI in the video makes it look like it has a malevolent face, with two huge staring eyes it even has pupils!

Best Ever Image of a Star’s Surface and Atmosphere

Quote
First map of motion of material on a star other than the Sun

Quote
Using ESO’s Very Large Telescope Interferometer astronomers have constructed the most detailed image ever of a star — the red supergiant star Antares. They have also made the first map of the velocities of material in the atmosphere of a star other than the Sun, revealing unexpected turbulence in Antares’s huge extended atmosphere. The results were published in the journal Nature.

http://www.eso.org/public/news/eso1726/

https://youtu.be/05PH6zAcATE
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/29/2017 07:29 pm
Likely Transiting Exocomets Detected by Kepler by Visual Lightcurve Inspection

Quote
In January 2017, amateur astronomer Tom Jacobs proposed the idea of visually surveying the complete Q1-Q17 Kepler lightcurve archive spanning 201,250 target stars for Data Release 25 (Thompson et al. 2016) with professional astronomers Saul Rappaport and Andrew Vanderburg along with amateur astronomer Daryll LaCourse. "The survey was conducted using the LcTools software system (Kipping et al. 2015), a publicly available Windows-based set of applications designed for processing lightcurves in a fast and efficient manner. Two primary components from the system were utilized; LcGenerator for building lightcurves in bulk and LcViewer for visually inspecting plots of the lightcurve for signals of interest."

The team has worked on similar projects with the K2 campaigns. The survey lasted five months with one person (TJ) individually inspecting each lightcurve for interesting objects that were non periodic in nature. There were no predetermined search parameters. Everything was on the table and numerous flagged objects turned out to be data breaks and data processing anomalies (data glitches) upon subsequent analysis by Saul Rappaport and Andrew Vanderburg. Both veterans were indefatigable in supporting the search effort. On March 18th, KIC 35421116 was initially flagged for its three aperiodic transits and subsequently labeled and analyzed as exocomet candidates.

http://keplerlightcurves.blogspot.co.uk/2017/08/likely-transiting-exocomets-detected-by.html?m=1
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/29/2017 07:34 pm
Kepler space telescope discovers variability in the Seven Sisters

Quote
Most of the seven stars are revealed to be slowly-pulsating B stars, a class of variable star in which the star’s brightness changes with day-long periods. The frequencies of these pulsations are key to  exploring some of the poorly understood processes in the core of these stars.

The seventh star, Maia, is different: it varies with a regular period of 10 days. Previous studies have shown that Maia belongs to a class of stars with abnormal surface concentrations of some chemical elements such as manganese. To see if these things were related, a series of spectroscopic observations were taken with the Hertzsprung SONG Telescope.

“What we saw was that the brightness changes seen by Kepler go hand-in-hand with changes in the strength of manganese absorption in Maia’s atmosphere,” said Dr. Victoria Antoci, a co-author of the work and Assistant Professor at the Stellar Astrophysics Centre, Aarhus University. “We conclude that the variations are caused by a large chemical spot on the surface of the star, which comes in and out of view as the star rotates with a ten day period.”

“Sixty years ago, astronomers had thought they could see variability in Maia with periods of a few hours and suggested this was the first of a whole new class of variable stars they called ‘Maia Variables’,” White said, “but our new observations show that Maia is not itself a Maia Variable!”

No signs of exoplanetary transits were detected in this study, but the authors show that their new algorithm can attain the precision that will be needed for Kepler and future space telescopes such as the Transiting Exoplanet Survey Satellite (TESS) to detect planets transiting stars as bright as our neighbouring star Alpha Centauri. These nearby bright stars are the best targets for future missions and facilities such as the James Webb Space Telescope, which is due to launch in late 2018.

https://astronomynow.com/2017/08/29/kepler-space-telescope-discovers-variability-in-the-seven-sisters/
Title: Exoplanets And Stars Thread
Post by: Star One on 08/30/2017 07:00 pm
Exoplanet-Hunters Detect Two New “Warm Jupiters”

Quote
The study of extra-solar planets has turned up some rather interesting candidates in the past few years. As of August 1st, 2017, a total of 3,639 exoplanets have been discovered in 2,729 planetary systems and 612 multiple planetary systems. Many of these discoveries have challenged conventional thinking about planets, especially where their sizes and distances from their suns are concerned.

According to a study by an international team of astronomers, the latest exoplanet discoveries are in keeping with this trend. Known as EPIC 211418729b and EPIC 211442297b, these two gas giants orbit stars that are located about 1569 and 1360 light-years from Earth (respectively) and are similar in size to Jupiter. Combined with their relatively close orbit to their stars, the team has designated them as “Warm Jupiters”.

The study, titled “EPIC 211418729b and EPIC 211442297b: Two Transiting Warm Jupiters“, recently appeared online. Led by Avi Shporer – a postdoctoral scholar with the Geological and Planetary Sciences (GPS) division at the California Institute of Technology (Caltech) – the team relied on data from the Kepler and K2 missions, and follow-up observations with multiple ground-based telescopes, to determine the sizes, masses and orbits of these planets.

https://www.universetoday.com/137001/exoplanet-hunters-detect-two-new-warm-jupiters/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/31/2017 05:57 am
Distant galaxy sends out 15 high-energy radio bursts

Quote
Breakthrough Listen, an initiative to find signs of intelligent life in the universe, has detected 15 brief but powerful radio pulses emanating from a mysterious and repeating source – FRB 121102 – far across the universe.

Fast radio bursts are brief, bright pulses of radio emission from distant but largely unknown sources, and FRB 121102 is the only one known to repeat: more than 150 high-energy bursts have been observed coming from the object, which was identified last year as a dwarf galaxy about 3 billion light years from Earth.

Possible explanations for the repeating bursts range from outbursts from rotating neutron stars with extremely strong magnetic fields – so-called magnetars – to a more speculative idea: They are directed energy sources, powerful laser bursts used by extraterrestrial civilizations to power spacecraft, akin to Breakthrough Starshot's plan to use powerful laser pulses to propel nano-spacecraft to Earth's nearest star, Proxima Centauri.

"Bursts from this source have never been seen at this high a frequency," said Andrew Siemion, director of the Berkeley SETI Research Center and of the Breakthrough Listen program.

https://m.phys.org/news/2017-08-distant-galaxy-high-energy-radio.html
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 08/31/2017 10:24 pm
Close encounters of the stellar kind

Quote
Understanding the past and future motions of stars is a key goal of Gaia as it collects precise data on stellar positions and motions over its five-year mission. After 14 months, the first catalogue of more than a billion stars was recently released, which included the distances and the motions across the sky for more than two million stars.

By combining the new results with existing information, astronomers began a detailed, large-scale search for stars passing close to our sun.

So far, the motions relative to the sun of more than 300 000 stars have been traced through the galaxy and their closest approach determined for up to five million years in the past and future.

Of them, 97 stars were found that will pass within 150 trillion kilometres, while 16 come within about 60 trillion km.

While the 16 are considered reasonably near, a particularly close encounter of one star, Gliese 710, in 1.3 million years' time, stands out. It is predicted to pass within just 2.3 trillion km or about 16 000 Earth–sun distances, well within the Oort Cloud.

The star is already well-documented, and thanks to the Gaia data, the estimated encounter distance has recently been revised. Previously, there was a 90% degree of certainty that it would come within 3.1–13.6 trillion kilometres. Now, the more accurate data suggest that it will come within 1.5–3.2 trillion km, with 2.3 trillion km most likely.

Furthermore, although Gliese 710 has a mass of 60% that of our sun, it travels much slower than most stars: nearly 50 000 km/h at closest approach, compared with the average 100 000 km/h.

The speed of its passage means it will have plenty of time to exert its gravitational influence on bodies in the Oort Cloud, potentially sending showers of comets into the solar system.

Despite its slower pace, it will still appear as the brightest, fastest object in the night sky at closest approach.

https://m.phys.org/news/2017-08-encounters-stellar-kind.html
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/01/2017 07:12 pm
Asteroseismic masses of retired planet-hosting A-stars using SONG

Quote
To better understand how planets form, it is important to study planet occurrence rates as a function of stellar mass. However, estimating masses of field stars is often difficult. Over the past decade, a controversy has arisen about the inferred occurrence rate of gas-giant planets around evolved intermediate-mass stars -- the so-called `retired A-stars'. The high masses of these red-giant planet hosts, derived using spectroscopic information and stellar evolution models, have been called into question. Here we address the controversy by determining the masses of eight evolved planet-hosting stars using asteroseismology. We compare the masses with spectroscopic-based masses from the Exoplanet Orbit Database that were previously adopted to infer properties of the exoplanets and their hosts. We find a significant one-sided offset between the two sets of masses for stars with spectroscopic masses above roughly 1.6Msun, suggestive of an average 15--20% overestimate of the adopted spectroscopic-based masses. The only star in our sample well below this mass limit is also the only one not showing this offset. Finally, we note that the scatter across literature values of spectroscopic-based masses often exceed their formal uncertainties, making it comparable to the offset we report here.

https://arxiv.org/abs/1708.09613
Title: Exoplanets And Stars Thread
Post by: Star One on 09/01/2017 07:22 pm
In relation to Gliese 710 I know the Sun couldn't capture another star if it wandered close to the Solar System, but could it capture something less massive like a brown dwarf if one did the same thing?

https://youtu.be/zpagMLf2yOg
Title: Re: Exoplanets And Stars Thread
Post by: whitelancer64 on 09/01/2017 07:55 pm
In relation to Gliese 710 I know the Sun couldn't capture another star if it wandered close to the Solar System, but could it capture something less massive like a brown dwarf if one did the same thing?


No, and for the same reason. In order to be captured, the object has to slow down. The only way for a body wandering close to our star to be captured by its gravity is for the body to exchange momentum with another body - for example, by gravitationally interacting with Jupiter and throwing it into a different orbit, or ejecting it from the Solar System entirely.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/01/2017 08:22 pm
In relation to Gliese 710 I know the Sun couldn't capture another star if it wandered close to the Solar System, but could it capture something less massive like a brown dwarf if one did the same thing?


No, and for the same reason. In order to be captured, the object has to slow down. The only way for a body wandering close to our star to be captured by its gravity is for the body to exchange momentum with another body - for example, by gravitationally interacting with Jupiter and throwing it into a different orbit, or ejecting it from the Solar System entirely.

I suppose that's why if it exists the captured planet theory is disfavoured for planet nine.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 09/01/2017 09:33 pm
In relation to Gliese 710 I know the Sun couldn't capture another star if it wandered close to the Solar System, but could it capture something less massive like a brown dwarf if one did the same thing?


No, and for the same reason. In order to be captured, the object has to slow down. The only way for a body wandering close to our star to be captured by its gravity is for the body to exchange momentum with another body - for example, by gravitationally interacting with Jupiter and throwing it into a different orbit, or ejecting it from the Solar System entirely.

An alternative scenario is where the object that ends up being captured is part of a binary pair. This is one hypothesis for the capture of Triton by Neptune (Neptune’s capture of its moon Triton in a binary-planet gravitational encounter (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.568.9568&rep=rep1&type=pdf) (pdf)).
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/03/2017 09:33 am
Main reason I am posting this video is he mentions there has been further FRB detections since the announcement above. I like his videos as he keeps a level head unlike some on YouTube & generally makes statements in reference to papers he links to.

https://youtu.be/h_EJYM4utEM
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/04/2017 04:28 pm
Supermassive black hole discovered near heart of the Milky Way

Quote
An enormous black hole one hundred thousand times more massive than the sun has been found hiding in a toxic gas cloud wafting around near the heart of the Milky Way.

If the discovery is confirmed, the invisible behemoth will rank as the second largest black hole ever seen in the Milky Way after the supermassive black hole known as Sagittarius A* that is anchored at the very centre of the galaxy.

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Oka, whose research is published in the journal Nature Astronomy, said the newly-found black hole could be the core of an old dwarf galaxy that was cannibalised during the formation of the Milky Way billions of years ago.

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All of which points to the fate that awaits the newly-found black hole. In time, Oka said, the object will be drawn towards Sagittarius A* and sink into it, making the supermassive black hole at the heart of the Milky Way even more massive.

https://www.theguardian.com/science/2017/sep/04/supermassive-black-hole-discovered-near-heart-of-the-milky-way
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 09/04/2017 10:56 pm
A modified CoRoT detrend algorithm and the discovery of a new planetary companion (https://arxiv.org/abs/1709.00351)

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We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromatic light curves. By means of robust statistics and better handling of short term variability, the implementation decreases the systematic light curve variations and improves the detection of exoplanets when compared with the original algorithm. All CoRoT chromatic light curves (a total of 65,655) were analysed with our algorithm. Dozens of new transit candidates and all previously known CoRoT exoplanets were rediscovered in those light curves using a box-fitting algorithm. For three of the new cases spectroscopic measurements of the candidates' host stars were retrieved from the ESO Science Archive Facility and used to calculate stellar parameters and, in the best cases, radial velocities. In addition to our improved detrend technique we announce the discovery of a planet that orbits a 0.79+0.08−0.09R⊙ star with a period of 6.71837±0.00001 days and has 0.57+0.06−0.05RJ and 0.15±0.10MJ. We also present the analysis of two cases in which parameters found suggest the existence of possible planetary companions.
Title: Exoplanets And Stars Thread
Post by: Star One on 09/05/2017 08:59 am
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Large solar storms, responsible for the northern lights, may have played a role in the strandings of 29 sperm whales in the North Sea early in 2016.

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Dr Vanselow and his colleagues studied the connection between whale strandings and two major solar storms that took place at the very end of December in 2015.
These produced huge displays of the Aurora Borealis that were seen in many parts of Scotland and elsewhere.
Looking specifically at the region around Shetland, the scientists found that these solar events would have caused short-term shifts in the magnetic field of up to 460km, in the area between the islands and Norway.
This could have caused sperm whales in the region to move in the wrong direction.
They also believe that sperm whales see a regular magnetic anomaly off the Norwegian coast as a "geomagnetic mountain chain", a kind of guardrail that prevents them from entering the North Sea.
The solar storms may have nullified this effect, rendering the mountain chain invisible and allowing the whales to swim through into the North Sea.

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Nasa has also been investigating the question of whether solar storms can affect a whole range of cetaceans around the world.
A team of researchers is shortly to publish a research paper on the connection between strandings in Cape Cod and geomagnetic storms. They say the Venselow paper is "well founded".
"It is one potential mechanism for having animals confused, I think it's a credible theory," Dr Antti Pulkkinen, who is leading the Nasa project, told BBC News.
"But does their paper prove that is the case? I don't think so."
"Having looked at this problem from a data analysis point of view, it is not a single factor that contributes to this.
"Things need to line up from multiple different perspectives for these events to take place."

http://www.bbc.co.uk/news/science-environment-41110082
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/05/2017 04:32 pm
The Surface UV Environment on Planets Orbiting M-Dwarfs: Implications for Prebiotic Chemistry & Need for Experimental Follow-Up

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Potentially-habitable planets orbiting M-dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years due to a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, and especially the origin of RNA. Characterizing the UV environment on M-dwarfs planets is important to understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M-dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically-important photoprocesses. We find that M-dwarf planets have access to 100-1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently-discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

https://arxiv.org/abs/1705.02350
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/05/2017 09:46 pm
Shocking discovery explains powerful novae

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Employing two powerful telescopes, astronomers at Michigan State University have proven a theory that explains these super-luminous novae and other astronomical explosions. The results, published in the current issue of Nature Astronomy, indicate that powerful shockwaves amplify the explosions beyond any traditional scale for nuclear explosions.

“Astronomers have long thought the energy from novae was dominated by the white dwarf, controlling how much light and energy are emitted,” said Laura Chomiuk, MSU astronomer and study co-author. “What we discovered, however, was a completely different source of energy — shockwaves that can dominate the entire explosion.”

As the explosion begins, it ejects a cooler, slower wave of gaseous material, relatively speaking. Behind it, though, is a hot, fast wave speeding right behind it. The collision of the two ejections produces a shockwave, which results in a spectacular explosion of heat and light.

“The bigger the shock, the brighter the nova,” Chomiuk said. “We believe it’s the speed of the second wave that influences the explosion.”

This study explains a theory held by Brian Metzger, Columbia University astronomer, who also is a co-author for this paper.

Now that the theory has been proven, astronomers use novae to better understand other super-charged explosions, like those that mark the death of massive stars in galaxies far away.

https://astronomynow.com/2017/09/05/shocking-discovery-explains-powerful-novae/
Title: Exoplanets And Stars Thread
Post by: Star One on 09/06/2017 07:09 pm
X-rays reveal temperament of possible planet-hosting stars

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A new X-ray study has revealed that stars like the Sun and their less massive cousins calm down surprisingly quickly after a turbulent youth. This result has positive implications for the long-term habitability of planets orbiting such stars.

https://astronomynow.com/2017/09/06/x-rays-reveal-temperament-of-possible-planet-hosting-stars/

Study of Uranus suggests some of its moons are on a collision course

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In studying the orbits of the moons, the researchers found that Cressida is on a path that will cause it to collide with another moon called Desdemona, which currently moves in an orbit just 900 kilometers from Cressida's. The gravity of Cressida is slowly pulling them closer together and will cause them to crash into one another in approximately 1 million years. They also found the same to be true for Cupid and Belinda, which will collide sometime later.

The researchers note that material in the inner rings around Uranus appears likely to be the remnants of other moons that were destroyed when they collided.

https://phys.org/news/2017-09-uranus-moons-collision.amp
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/07/2017 04:41 pm
Astrometric exoplanet detectability and the Earth orbital motion

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Astrometric exoplanet discovery relies on detection of stellar motion caused by planetary companions. Systems with orbital period close to one year may escape detection if orbital motion of their host stars are observationally indistinguishable from parallax effect. Additionally, astrometric solution may produce a biased parallax estimation for such systems. We examine effects of orbital motion of the Earth on astrometric detectability in terms of correlation between the Earth's orbital position and position of the star relative to system barycentre. The χ2 statistic for parallax estimation is calculated analytically, leading to expressions that relate the decrease in detectability and accompanying parallax bias to the position correlation function. The effects of the Earth motion's critically depend on orbital period, diminishing rapidly as period deviates from one year. Selection effects against one-year period systems is therefore expected. Statistical estimation shows that corresponding loss of sensitivity is equivalent to a 10 per cent increase in detection threshold. Consideration of eccentric orbits shows that the Earth's motion has no effect on detectability for e≥0.5. Dependence of detectability on other parameters, such as orbital phases and inclination of the orbit plane to the ecliptic, are smooth and monotonic because they are described by simple trigonometric functions.

https://arxiv.org/abs/1709.00290
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/07/2017 07:16 pm
Extreme’ telescopes find the second-fastest-spinning pulsar

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By following up on mysterious high-energy sources mapped out by NASA’s Fermi Gamma-ray Space Telescope, the Netherlands-based Low Frequency Array (LOFAR) radio telescope has identified a pulsar spinning at more than 42,000 revolutions per minute, making it the second-fastest known.

https://astronomynow.com/2017/09/06/extreme-telescopes-find-the-second-fastest-spinning-pulsar/
Title: Re: Exoplanets And Stars Thread
Post by: hop on 09/08/2017 07:19 am
A fun one: From what stars are we a transiting planet?

Transit Visibility Zones of the Solar System Planets (https://arxiv.org/abs/1709.02211) R. Wells, K. Poppenhaeger, C. A. Watson, R. Heller

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The detection of thousands of extrasolar planets by the transit method naturally raises the question of whether potential extrasolar observers could detect the transits of the Solar System planets. We present a comprehensive analysis of the regions in the sky from where transit events of the Solar System planets can be detected. We specify how many different Solar System planets can be observed from any given point in the sky, and find the maximum number to be three. We report the probabilities of a randomly positioned external observer to be able to observe single and multiple Solar System planet transits; specifically, we find a probability of 2.518% to be able to observe at least one transiting planet, 0.229% for at least two transiting planets, and 0.027% for three transiting planets. We identify 68 known exoplanets that have a favourable geometric perspective to allow transit detections in the Solar System and we show how the ongoing K2 mission will extend this list. We use occurrence rates of exoplanets to estimate that there are 3.2±1.2 and 6.6+1.3−0.8 temperate Earth-sized planets orbiting GK and M dwarf stars brighter than V=13 and V=16 respectively, that are located in the Earth's transit zone.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 09/08/2017 11:00 pm
A System of Three Super Earths Transiting the Late K-Dwarf GJ 9827 at Thirty Parsecs (https://arxiv.org/abs/1709.01957) (arXiv)

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We report the discovery of three small transiting planets orbiting GJ 9827, a bright (K = 7.2) nearby late K-type dwarf star. GJ 9827 hosts a 1.64+0.22−0.20 R⊕ super Earth on a 1.2 day period, a 1.29+0.17−0.16 R⊕ super Earth on a 3.6 day period, and a 2.08+0.28−0.26 R⊕ super Earth on a 6.2 day period. The radii of the planets transiting GJ 9827 span the transition between predominantly rocky and gaseous planets, and GJ 9827 b and c fall in or close to the known gap in the radius distribution of small planets between these populations. At a distance of ∼30 parsecs, GJ 9827 is the closest exoplanet host discovered by K2 to date, making these planets well-suited for atmospheric studies with the upcoming James Webb Space Telescope. The GJ 9827 system provides a valuable opportunity to characterize interior structure and atmospheric properties of coeval planets spanning the rocky to gaseous transition.

The 'known gap' is the so-called Fulton Gap. I guess the name hasn't stuck with the wider astronomical community (yet?). :)
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/11/2017 07:15 pm
Gravitational Waves will let us see Inside Stars as Supernovae Happen

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However, according to a team of astronomers from Glasgow and Arizona, astronomers need not limit themselves to detecting waves caused by massive gravitational mergers. According to a study they recently produced, the Advanced LIGO, GEO 600, and Virgo gravitational-wave detector network could also detect the gravitational waves created by supernova. In so doing, astronomers will able to see inside the hearts of collapsing stars for the first time.

The study, titled “Inferring the Core-Collapse Supernova Explosion Mechanism with Three-Dimensional Gravitational-Wave Simulations“, recently appeared online. Led by Jade Powell, who recently finished her PhD at the Institute for Gravitational Research at the University of Glasgow, the team argue that current gravitational wave experiments should be able to detect the waves created by Core Collapse Supernovae (CSNe).

https://www.universetoday.com/137068/gravitational-waves-will-let-us-see-inside-stars-supernovae-happen/amp/
Title: Re: Exoplanets And Stars Thread
Post by: redliox on 09/12/2017 12:06 am
How large does a scope need to be to directly image one of the nearer exoplanets?

Let's assume we're targeting Epsilon Eridani's planet and the 'scope has a coronograph built in.  Anyone able to crunch the numbers?
Title: Re: Exoplanets And Stars Thread
Post by: jebbo on 09/12/2017 11:07 am
How large does a scope need to be to directly image one of the nearer exoplanets?

Let's assume we're targeting Epsilon Eridani's planet and the 'scope has a coronograph built in.  Anyone able to crunch the numbers?

You really don't need that large a telescope (assuming space based).  The key things are the Inner Working Angle and contrast ratio between the star and planet.

For example, MAPLE-150 (1.5m) would be able to resolve epsilon Eridani b:
http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf (http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf)

--- Tony
Title: Re: Exoplanets And Stars Thread
Post by: redliox on 09/12/2017 06:11 pm
How large does a scope need to be to directly image one of the nearer exoplanets?

Let's assume we're targeting Epsilon Eridani's planet and the 'scope has a coronograph built in.  Anyone able to crunch the numbers?

You really don't need that large a telescope (assuming space based).  The key things are the Inner Working Angle and contrast ratio between the star and planet.

For example, MAPLE-150 (1.5m) would be able to resolve epsilon Eridani b:
http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf (http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf)

--- Tony

That's hopeful.  I believe I can understand what you mean by ratio (such as how a bright distant Jupiter might be easier to detect that a dark SuperEarth), but elaborate on IWA.  What else would allow an exoplanet to be more than a pixel in an image as well?
Title: Re: Exoplanets And Stars Thread
Post by: as58 on 09/12/2017 07:40 pm
How large does a scope need to be to directly image one of the nearer exoplanets?

Let's assume we're targeting Epsilon Eridani's planet and the 'scope has a coronograph built in.  Anyone able to crunch the numbers?

You really don't need that large a telescope (assuming space based).  The key things are the Inner Working Angle and contrast ratio between the star and planet.

For example, MAPLE-150 (1.5m) would be able to resolve epsilon Eridani b:
http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf (http://www.nuvucameras.com/wp-content/uploads/2014/09/91432R.pdf)

--- Tony

That's hopeful.  I believe I can understand what you mean by ratio (such as how a bright distant Jupiter might be easier to detect that a dark SuperEarth), but elaborate on IWA.  What else would allow an exoplanet to be more than a pixel in an image as well?

IWA is the smallest angle where at least 50% percent of the light is transmitted by the coronagraph; at smaller angles most of the light from the planet is blocked along with stellar light. Best coronagraph designs achieve IWA of about 2*lambda/D. But if you mean by "resolving" seeing the planet as something other than just a single pixel, much bigger telescopes are needed.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/13/2017 08:48 pm
Boiling exoplanet has titanium atmosphere

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The exoplanet WASP-19b has huge amounts of titanium oxide in its atmosphere, causing the atmosphere to 'reverse' so some of the upper layers are warmer than those lower down.

http://m.skyatnightmagazine.com/news/boiling-exoplanet-has-titanium-atmosphere
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/15/2017 07:18 pm
NASA's Hubble Captures Blistering Pitch-Black Planet
NASA's Hubble Space Telescope has observed a planet outside our solar system that looks as black as fresh asphalt because it eats light rather than reflecting it back into space. This light-eating prowess is due to the planet's unique capability to trap at least 94 percent of the visible starlight falling into its atmosphere.

The oddball exoplanet, called WASP-12b, is one of a class of so-called "hot Jupiters," gigantic, gaseous planets that orbit very close to their host star and are heated to extreme temperatures. The planet's atmosphere is so hot that most molecules are unable to survive on the blistering day side of the planet, where the temperature is 4,600 degrees Fahrenheit. Therefore, clouds probably cannot form to reflect light back into space. Instead, incoming light penetrates deep into the planet's atmosphere where it is absorbed by hydrogen atoms and converted to heat energy.

"We did not expect to find such a dark exoplanet," said Taylor Bell of McGill University and the Institute for Research on Exoplanets in Montreal, Quebec, Canada, lead researcher of the Hubble study. "Most hot Jupiters reflect about 40 percent of starlight."

But the planet's nighttime side is a different story. WASP-12b has a fixed day side and night side because it orbits so close to the star that it is tidally locked. The nighttime side is more than 2,000 degrees Fahrenheit cooler, which allows water vapor and clouds to form. Previous Hubble observations of the day/night boundary detected evidence of water vapor and possibly clouds and hazes in the atmosphere. WASP-12b is about 2 million miles away from its star and completes an orbit once a day.

"This new Hubble research further demonstrates the vast diversity among the strange population of hot Jupiters," Bell said. "You can have planets like WASP-12b that are 4,600 degrees Fahrenheit and some that are 2,200 degrees Fahrenheit, and they're both called hot Jupiters. Past observations of hot Jupiters indicate that the temperature difference between the day and night sides of the planet increases with hotter day sides. This previous research suggests that more heat is being pumped into the day side of the planet, but the processes, such as winds, that carry the heat to the night side of the planet don't keep up the pace."

The researchers determined the planet's light-eating capabilities by using Hubble's Space Telescope Imaging Spectrograph to search in mostly visible light for a tiny dip in starlight as the planet passed directly behind the star. The amount of dimming tells astronomers how much reflected light is given off by the planet. However, the observations did not detect reflected light, meaning that the daytime side of the planet is absorbing almost all the starlight falling onto it.

First spotted in 2008, WASP-12b circles a Sun-like star residing 1,400 light-years away in the constellation Auriga. Since its discovery, several telescopes have studied the exoplanet, including Hubble, NASA's Spitzer Space Telescope, and NASA's Chandra X-ray Observatory. Previous observations by Hubble's Cosmic Origins Spectrograph (COS) revealed that the planet may be downsizing. COS detected material from the planet's super-heated atmosphere spilling onto the star.

The results appear in the Sept. 14 issue of The Astrophysical Journal Letters.

https://www.nasa.gov/feature/goddard/2017/hubble-captures-blistering-pitch-black-planet
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 09/15/2017 10:22 pm
Bayesian Analysis of Hot Jupiter Radius Anomalies: Evidence for Ohmic Dissipation? (https://arxiv.org/abs/1709.04539) (arXiv)

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The cause of hot Jupiter radius inflation, where giant planets with Teq >1000 K are significantly larger than expected, is an open question and the subject of many proposed explanations. Rather than examine these models individually, this work seeks to characterize the anomalous heating as a function of incident flux, ϵ(F), needed to inflate the population of planets to their observed sizes. We then compare that result to theoretical predictions for various models. We examine the population of about 300 giant planets with well-determined masses and radii and apply thermal evolution and Bayesian statistical models to infer the anomalous power as a function of incident flux that best reproduces the observed radii. First, we observe that the inflation of planets below about M=0.5MJ appears very different than their higher mass counterparts, perhaps as the result of mass loss or an inefficient heating mechanism. As such, we exclude planets below this threshold. Next, we show with strong significance that ϵ(F) increases with Teq towards a maximum of ∼2.5% at Teq≈1500 K, and then decreases as temperatures increase further, falling to ∼0.2% at Teff=2500 K. This high-flux decrease in inflation efficiency was predicted by the Ohmic dissipation model of giant planet inflation but not other models. We also explicitly check the thermal tides model and find that it predicts far more variance in radii than is observed. Thus, our results provide evidence for the Ohmic dissipation model and a functional form for ϵ(F) that any future theories of hot Jupiter radii can be tested against.

It's interesting that exoplanet studies are quickly finding these apparent physical boundaries separating planets into different classes.
Title: Exoplanets And Stars Thread
Post by: Star One on 09/17/2017 07:05 pm
Diamonds Really Do Rain on Neptune, Experiments Conclude

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Researchers subjected hydrocarbon samples in a laboratory to Neptune-like pressures. The samples, reminiscent of molecules found in the ice giant’s atmosphere, compressed into nanodiamonds.

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Knowing how hydrocarbons might behave deep within an ice giant’s atmosphere will affect our understanding of how atmospheres transport heat and evolve over time, explained Kraus. What’s more, the implications of this research extend beyond our solar system to exoplanets, as a large fraction of the known exoplanets are similar in size or mass to our ice giants.

The ability to model an ice giant atmosphere’s density from the top down to the core is a critical part of characterizing that planet. For example, an atmosphere made mostly of hydrogen is much puffier than one with diamonds, Kraus noted.

A diamond-studded atmosphere also likely behaves very differently than one without diamonds. For example, atmospheric convection might have to overcome more hurdles, which may lead to sharp changes in chemical composition between different atmospheric layers, the researchers said. This could also inhibit heat flow.

“These experiments can be used to improve our understanding of the behavior of common materials in the universe at high pressures and temperatures, which has a direct connection to modeling planetary interiors,” said Ravit Helled, a computational science and theoretical astrophysics professor at the University of Zurich in Switzerland, who was not involved in the study.

https://eos.org/articles/diamonds-really-do-rain-on-neptune-experiments-conclude
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/18/2017 08:04 pm
Do planets remember how they formed?

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One of the most directly observable features of a transiting multi-planet system is their size-ordering when ranked in orbital separation. Kepler has revealed a rich diversity of outcomes, from perfectly ordered systems, like Kepler-80, to ostensibly disordered systems, like Kepler-20. Under the hypothesis that systems are born via preferred formation pathways, one might reasonably expect non-random size-orderings reflecting these processes. However, subsequent dynamical evolution, often chaotic and turbulent in nature, may erode this information and so here we ask - do systems remember how they formed? To address this, we devise a model to define the entropy of a planetary system's size-ordering, by first comparing differences between neighboring planets and then extending to accommodate differences across the chain. We derive closed-form solutions for many of the micro state occupancies and provide public code with look-up tables to compute entropy for up to ten-planet systems. All three proposed entropy definitions exhibit the expected property that their credible interval increases with respect to a proxy for time. We find that the observed Kepler multis display a highly significant deficit in entropy compared to a randomly generated population. Incorporating a filter for systems deemed likely to be dynamically packed, we show that this result is robust against the possibility of missing planets too. Put together, our work establishes that Kepler systems do indeed remember something of their younger years and highlights the value of information theory for exoplanetary science.

https://arxiv.org/abs/1709.04987
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/18/2017 08:30 pm
New supernova analysis reframes dark energy debate

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The accelerating expansion of the universe may not be real, but could just be an apparent effect, according to new research published in the journal Monthly Notices of the Royal Astronomical Society. The new study — by a group at the University of Canterbury in Christchurch, New Zealand — finds the fit of Type Ia supernovae to a model universe with no dark energy to be very slightly better than the fit to the standard dark energy model.

https://astronomynow.com/2017/09/18/new-supernova-analysis-reframes-dark-energy-debate/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/21/2017 04:03 pm
The empty primordial asteroid belt

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Abstract
The asteroid belt contains less than a thousandth of Earth’s mass and is radially segregated, with S-types dominating the inner belt and C-types the outer belt. It is generally assumed that the belt formed with far more mass and was later strongly depleted. We show that the present-day asteroid belt is consistent with having formed empty, without any planetesimals between Mars and Jupiter’s present-day orbits. This is consistent with models in which drifting dust is concentrated into an isolated annulus of terrestrial planetesimals. Gravitational scattering during terrestrial planet formation causes radial spreading, transporting planetesimals from inside 1 to 1.5 astronomical units out to the belt. Several times the total current mass in S-types is implanted, with a preference for the inner main belt. C-types are implanted from the outside, as the giant planets’ gas accretion destabilizes nearby planetesimals and injects a fraction into the asteroid belt, preferentially in the outer main belt. These implantation mechanisms are simple by-products of terrestrial and giant planet formation. The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself.

http://advances.sciencemag.org/content/3/9/e1701138
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/22/2017 09:22 am

Astronomers Have Spotted a Strange Hybrid Asteroid in Our Solar System

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The Hubble space telescope has seen a lot of weird things that defy easy definition. Here's one more for the list – a binary asteroid that's also a comet.

Astronomers have found a pair of them, in fact, swirling around one another in the asteroid belt while leaving a stream of dust in their wake. Not only is it a beautiful example of how nature DNGAF about our categories, it raises some interesting questions on how many of these hybrids might be out there.

The binary object itself was first spotted back in 2006 as part of the asteroid-searching Spacewatch program, resulting in it getting the not-so-glamorous name 2006 VW139.

It wasn't until 2012 that astronomers realised something odd about it; this thing that was an asteroid with comet-like characteristics, namely a streaming tail.

So-called main belt comets aren't new, but they're by no means common either. This asteroid is just one of about a dozen such objects ever discovered.

What makes this particular one so unique is that it's in two pieces.

2006 VW139 is made of a pair of equal-sized lumps orbiting one another at a distance of just under 100 kilometres (about 60 miles).

http://www.sciencealert.com/astronomers-spotted-a-weird-new-object-in-asteroid-belt-and-it-s-gorgeous
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/22/2017 04:46 pm
A Fast Radio Burst Occurs Every Second throughout the Observable Universe

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Abstract
Recent multi-telescope observations of the repeating fast radio burst (FRB) FRB 121102 reveal a Gaussian-like spectral profile and associate the event with a dwarf metal-poor galaxy at a cosmological redshift of 0.19. Assuming that this event represents the entire FRB population, we make predictions for the expected number counts of FRBs observable by future radio telescopes between 50 MHz and 3.5 GHz. We vary our model assumptions to bracket the expected rate of FRBs and find that it exceeds one FRB per second per sky when accounting for faint sources. We show that future low-frequency radio telescopes, such as the Square Kilometre Array, could detect more than one FRB per minute over the entire sky originating from the epoch of reionization.

http://iopscience.iop.org/article/10.3847/2041-8213/aa8905/meta
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/25/2017 08:07 pm
Star nicknamed Kronos after eating its own planetary children

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A sun-like star seems to have devoured some of its own planetary offspring, prompting researchers to nickname it after the titan Kronos from Greek mythology.

The star HD 240430 is part of a binary system with HD 240429, and the two have now been nicknamed Kronos and Krios. The pair travel through the galaxy side by side some 320 light years from Earth.

They both seem to be about 4 billion years old, suggesting they were born from the same interstellar cloud, and initially shared the same chemical make-up.

But an analysis by Semyeong Oh at Princeton University and her team suggests the twins have led very different lives. Krios has noticeably smaller concentrations of elements like lithium, magnesium and iron floating in its atmosphere than its companion Kronos does.

In fact, the stars are more chemically different than any pair yet discovered. “I initially thought these two stars must not be in a binary,” says Oh.

https://www.newscientist.com/article/2148182-star-nicknamed-kronos-after-eating-its-own-planetary-children/
Title: Re: Exoplanets And Stars Thread
Post by: redliox on 09/26/2017 01:43 am
Star nicknamed Kronos after eating its own planetary children

Quote
A sun-like star seems to have devoured some of its own planetary offspring, prompting researchers to nickname it after the titan Kronos from Greek mythology.

The star HD 240430 is part of a binary system with HD 240429, and the two have now been nicknamed Kronos and Krios. The pair travel through the galaxy side by side some 320 light years from Earth.

They both seem to be about 4 billion years old, suggesting they were born from the same interstellar cloud, and initially shared the same chemical make-up.

But an analysis by Semyeong Oh at Princeton University and her team suggests the twins have led very different lives. Krios has noticeably smaller concentrations of elements like lithium, magnesium and iron floating in its atmosphere than its companion Kronos does.

In fact, the stars are more chemically different than any pair yet discovered. “I initially thought these two stars must not be in a binary,” says Oh.

https://www.newscientist.com/article/2148182-star-nicknamed-kronos-after-eating-its-own-planetary-children/

Considering these theories are applicable to our own solar system's migrating planets, could there be a way to chemically discern how many planets the sun may have consumed in the past?
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/26/2017 04:56 pm
Quote
Comparative exoplanetology? That’s the striking term that Angelos Tsiaras, lead author of a new paper on exoplanet atmospheres, uses to describe the field today. Kepler’s valuable statistical look at a crowded starfield has given us insights into the sheer range of outcomes around other stars, but we’re already moving into the next phase, studying planetary atmospheres. And as the Tsiaras paper shows, constructing the first atmospheric surveys.

Tsiaras (University College, London) assembled a team of European researchers that examined 30 exoplanets, constructing their spectral profiles and analyzing them to uncover the characteristic signatures of the gases present. The study found atmospheres around 16 ‘hot Jupiters,’ learning that water vapor was present in each of them. Says Tsiaras:

“More than 3,000 exoplanets have been discovered but, so far, we’ve studied their atmospheres largely on an individual, case-by-case basis. Here, we’ve developed tools to assess the significance of atmospheric detections in catalogues of exoplanets. This kind of consistent study is essential for understanding the global population and potential classifications of these foreign worlds.”

https://www.centauri-dreams.org/?p=38547
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/27/2017 09:00 am
Most Super-Earths Are Likely Not Habitable

Quote
The tendency of planets to migrate early in a solar system’s history—like a planetary billiards game—would preclude the kind of stable environments that life needs to evolve. And a primitive, hydrogen-helium atmosphere would be very challenging for life. Exceptions to this general principle may still exist. For example, a planet’s original atmosphere can be lost due to radiation or impacts, as happened on Earth.

Even so, it seems that Earth’s mass is close to the optimum for a life-hosting planet. Given the new modeling results and insights, it also appears that most Super-Earths are likely not to be habitable. In the end, however, only observations will answer this question for certain. Fortunately, we should able to determine the atmospheric compositions of some Super-Earth planets within a decade.

Read more at http://www.airspacemag.com/daily-planet/most-super-earths-are-likely-not-habitable-180965030/#XKxZHGRWk2AmuYg1.99
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/27/2017 07:10 pm
NEWLY DISCOVERED STAR CLUSTER ANALYZED BY GAIA PROBE

https://www.universetoday.com/137305/newly-discovered-star-cluster-analyzed-gaia-probe/

Paper:

https://arxiv.org/pdf/1709.04022.pdf
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 09/30/2017 10:04 am
NASA's Hubble Observes the Farthest Active Inbound Comet Yet Seen

Quote
NASA's Hubble Space Telescope has photographed the farthest active inbound comet ever seen, at a whopping distance of 1.5 billion miles from the Sun (beyond Saturn's orbit). Slightly warmed by the remote Sun, it has already begun to develop an 80,000-mile-wide fuzzy cloud of dust, called a coma, enveloping a tiny, solid nucleus of frozen gas and dust. These observations represent the earliest signs of activity ever seen from a comet entering the solar system's planetary zone for the first time.

The comet, called C/2017 K2 (PANSTARRS) or "K2", has been travelling for millions of years from its home in the frigid outer reaches of the solar system, where the temperature is about minus 440 degrees Fahrenheit. The comet's orbit indicates that it came from the Oort Cloud, a spherical region almost a light-year in diameter and thought to contain hundreds of billions of comets. Comets are the icy leftovers from the formation of the solar system 4.6 billion years ago and therefore pristine in icy composition.

"K2 is so far from the Sun and so cold, we know for sure that the activity — all the fuzzy stuff making it look like a comet — is not produced, as in other comets, by the evaporation of water ice," said lead researcher David Jewitt of the University of California, Los Angeles. "Instead, we think the activity is due to the sublimation [a solid changing directly into a gas] of super-volatiles as K2 makes its maiden entry into the solar system's planetary zone. That's why it's special. This comet is so far away and so incredibly cold that water ice there is frozen like a rock."

Based on the Hubble observations of K2's coma, Jewitt suggests that sunlight is heating frozen volatile gases - such as oxygen, nitrogen, carbon dioxide, and carbon monoxide - that coat the comet's frigid surface. These icy volatiles lift off from the comet and release dust, forming the coma. Past studies of the composition of comets near the Sun have revealed the same mixture of volatile ices.

"I think these volatiles are spread all through K2, and in the beginning billions of years ago, they were probably all through every comet presently in the Oort Cloud," Jewitt said. "But the volatiles on the surface are the ones that absorb the heat from the Sun, so, in a sense, the comet is shedding its outer skin. Most comets are discovered much closer to the Sun, near Jupiter's orbit, so by the time we see them, these surface volatiles have already been baked off. That's why I think K2 is the most primitive comet we've seen."

K2 was discovered in May 2017 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii, a survey project of NASA's Near-Earth Object Observations Program. Jewitt used Hubble's Wide Field Camera 3 at the end of June to take a closer look at the icy visitor.

Hubble's sharp "eye" revealed the extent of the coma and also helped Jewitt estimate the size of the nucleus — less than 12 miles across — though the tenuous coma is 10 Earth diameters across.

This vast coma must have formed when the comet was even farther away from the Sun. Digging through archival images, Jewitt's team uncovered views of K2 and its fuzzy coma taken in 2013 by the Canada-France-Hawaii Telescope (CFHT) in Hawaii. But the object was then so faint that no one noticed it.

"We think the comet has been continuously active for at least four years," Jewitt said. "In the CFHT data, K2 had a coma already at 2 billion miles from the Sun, when it was between the orbits of Uranus and Neptune. It was already active, and I think it has been continuously active coming in. As it approaches the Sun, it's getting warmer and warmer, and the activity is ramping up."

But, curiously, the Hubble images do not show a tail flowing from K2, which is a signature of comets. The absence of such a feature indicates that particles lifting off the comet are too large for radiation pressure from the Sun to sweep them back into a tail.

Astronomers will have plenty of time to conduct detailed studies of K2. For the next five years, the comet will continue its journey into the inner solar system before it reaches its closest approach to the Sun in 2022 just beyond Mars' orbit. "We will be able to monitor for the first time the developing activity of a comet falling in from the Oort Cloud over an extraordinary range of distances," Jewitt said. "It should become more and more active as it nears the Sun and presumably will form a tail."

Jewitt said that NASA's James Webb Space Telescope, an infrared observatory scheduled to launch in 2018, could measure the heat from the nucleus, which would give astronomers a more accurate estimate of its size.

The team's results will appear in the September 28 issue of The Astrophysical Journal Letters.

http://hubblesite.org/news_release/news/2017-40
Title: Re: Exoplanets And Stars Thread
Post by: hop on 09/30/2017 10:01 pm
Paper the article above about C/2017 K2 (PANSTARRS) refers to
A Comet Active Beyond the Crystallization Zone  (https://arxiv.org/abs/1709.10079) David Jewitt, Man-To Hui, Max Mutchler, Harold Weaver, Jing Li, Jessica Agarwal

Quote
We present observations showing in-bound long-period comet We present observations showing in-bound long-period comet C/2017 K2 (PANSTARRS) to be active at record heliocentric distance. Nucleus temperatures are too low (60 K to 70 K) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. Using the Hubble Space Telescope we find a sharply-bounded, circularly symmetric dust coma 105 km in radius, with a total scattering cross section of ∼105 km2. The coma has a logarithmic surface brightness gradient -1 over much of its surface, indicating sustained, steady-state dust production. A lack of clear evidence for the action of solar radiation pressure suggests that the dust particles are large, with a mean size ≳ 0.1 mm. Using a coma convolution model, we find a limit to the apparent magnitude of the nucleus V> 25.2 (absolute magnitude H> 12.9). With assumed geometric albedo pV = 0.04, the limit to the nucleus circular equivalent radius is < 9 km. Pre-discovery observations from 2013 show that the comet was also active at 23.7 AU heliocentric distance. While neither water ice sublimation nor exothermic crystallization can account for the observed distant activity, the measured properties are consistent with activity driven by sublimating supervolatile ices such as CO2, CO, O2 and N2. Survival of supervolatiles at the nucleus surface is likely a result of the comet's recent arrival from the frigid Oort cloud. to be active at record heliocentric distance. Nucleus temperatures are too low (60 K to 70 K) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. Using the Hubble Space Telescope we find a sharply-bounded, circularly symmetric dust coma 105 km in radius, with a total scattering cross section of ∼105 km2. The coma has a logarithmic surface brightness gradient -1 over much of its surface, indicating sustained, steady-state dust production. A lack of clear evidence for the action of solar radiation pressure suggests that the dust particles are large, with a mean size ≳ 0.1 mm. Using a coma convolution model, we find a limit to the apparent magnitude of the nucleus V> 25.2 (absolute magnitude H> 12.9). With assumed geometric albedo pV = 0.04, the limit to the nucleus circular equivalent radius is < 9 km. Pre-discovery observations from 2013 show that the comet was also active at 23.7 AU heliocentric distance. While neither water ice sublimation nor exothermic crystallization can account for the observed distant activity, the measured properties are consistent with activity driven by sublimating supervolatile ices such as CO2, CO, O2 and N2. Survival of supervolatiles at the nucleus surface is likely a result of the comet's recent arrival from the frigid Oort cloud.
Title: Re: Exoplanets And Stars Thread
Post by: missinglink on 10/02/2017 03:04 am
enveloping a tiny, solid nucleus of frozen gas and dust . . .  estimate the size of the nucleus — less than 12 miles across
Twelve miles! Not so tiny. That could really ruin someone's day if it hits. Why worry about asteroids when comets are faster, bigger . . . and currently unstoppable even by targeted nukes.
Title: Re: Exoplanets And Stars Thread
Post by: bolun on 10/03/2017 09:27 am
BIOMARKER FOUND IN SPACE COMPLICATES SEARCH FOR LIFE ON EXOPLANETS

http://sci.esa.int/rosetta/59625-biomarker-found-in-space-complicates-search-for-life-on-exoplanets/

Quote
A molecule once thought to be a useful marker for life as we know it has been discovered around a young star and at a comet for the first time, suggesting these ingredients are inherited during the planet-forming phase.

The discovery of methyl chloride was made by the ground-based Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and by ESA's Rosetta spacecraft following Comet 67P/Churyumov-Gerasimenko. It is the simplest member of a class of molecules known as organohalogens, which contain halogens, such as chlorine or fluorine, bonded with carbon.

Methyl chloride is well known on Earth as being used in industry. It is also produced naturally by biological and geological activity: it is the most abundant organohalogen in Earth's atmosphere, with up to three megatonnes produced a year, primarily from biological processes.

As such, it had been identified as a possible 'biomarker' in the search for life at exoplanets. This has been called into question, however, now it is seen in environments not derived from living organisms, and instead as a raw ingredient from which planets could eventually form.

This is also the first time an organohalogen has been detected in space, indicating that halogen- and carbon-centred chemistries are more intertwined than previously thought.
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 10/08/2017 08:25 pm
Exterior Companions to Hot Jupiters Orbiting Cool Stars are Coplanar (https://arxiv.org/abs/1710.01737) (arXiv)
(Juliette C. Becker, Andrew Vanderburg, Fred C. Adams, Tali Khain, Marta Bryan)

Quote
The existence of hot Jupiters has challenged theories of planetary formation since the first extrasolar planets were detected. Giant planets are generally believed to form far from their host stars, where volatile materials like water exist in their solid phase, making it easier for giant planet cores to accumulate. Several mechanisms have been proposed to explain how giant planets can migrate inward from their birth sites to short-period orbits. One such mechanism, called Kozai-Lidov migration, requires the presence of distant companions in orbits inclined by more than ∼40 degrees with respect to the plane of the hot Jupiter's orbit. The high occurrence rate of wide companions in hot Jupiter systems lends support to this theory for migration. However, the exact orbital inclinations of these detected planetary and stellar companions is not known, so it is not clear whether the mutual inclination of these companions is large enough for the Kozai-Lidov process to operate. This paper shows that in systems orbiting cool stars with convective outer layers, the orbits of most wide planetary companions to hot Jupiters must be well aligned with the orbits of the hot Jupiters and the spins of the host stars. For a variety of possible distributions for the inclination of the companion, the width of the distribution must be less than ∼20 degrees to recreate the observations with good fidelity. As a result, the companion orbits are likely well-aligned with those of the hot Jupiters, and the Kozai-Lidov mechanism does not enforce migration in these systems.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/09/2017 04:41 pm
A 'Pale Green Dot': Why Proxima Centauri b May Have a Shiny Tint

Quote
A world orbiting the sun's closest stellar neighbor may have a shiny green tint to it — and not necessarily because it's covered in leafy plants.

Researchers have found a way to characterize potential auroras on the nearby exoplanet Proxima Centauri b and found that, if the planet sports oxygen in its atmosphere, the auroras may give the atmosphere a greenish cast.

"The northern and southern lights [on Proxima Centauri b] would be at least 100 times brighter than on Earth," Rodrigo Luger, a postdoctoral student at the University of Washington, who led the study of how the planet's auroras could be spotted from Earth, told Space.com by email. Luger said the auroras might be so bright as to be visible with very powerful telescopes. [Proxima b By the Numbers: Possibly Earth-Like World at the Next Star Over]

https://www.space.com/38397-proxima-centauri-planet-could-be-green.html
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/09/2017 07:24 pm
Scientists Just Found Half of the Missing Matter in Our Universe

Quote
Two teams of astronomers have found a way to observe the presence of the missing matter connecting the galaxies in the universe. This discovery can improve our understanding of how galaxies were formed in the years following the Big Bang.

https://futurism.com/scientists-just-found-half-of-the-missing-matter-in-our-universe/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/10/2017 03:26 pm
Astronomers find a Neptune-sized exoplanet in a binary star system

Quote
Using NASA's prolonged Kepler mission, known as K2, astronomers have discovered a new Neptune-sized planet in a binary star system in the Hyades open cluster. The newly found exoworld, designated K2-nnnA b, is the first known Neptune-sized planet in a binary system within an open cluster. The finding was reported Sept. 29 in a paper published on the arXiv pre-print server.

K2-nnnA b was initially spotted during K2's Campaign 13, conducted between March 8 and May 27, 2017. During this campaign, a team of astronomers led by David R. Ciardi of the California Institute of Technology (Caltech) observed a binary system named EPIC 247589423 consisting of a K-dwarf star and a late M-dwarf companion. As a result, the researchers identified a transit signal in the light curve of the binary.

https://m.phys.org/news/2017-10-astronomers-neptune-sized-exoplanet-binary-star.html
Title: Exoplanets And Stars Thread
Post by: Star One on 10/11/2017 07:40 pm
Distant dwarf planet near Pluto has a ring that no one expected

Quote
A ring has been found around Haumea, a world more than 2 billion kilometres beyond Pluto. The ring is the most distant ever seen in our solar system.

“This is a landmark discovery,” says Alan Stern at the Southwest Research Institute in Boulder, Colorado. “It’s very exciting.”

Until recently, the only known rings circled giant planets such as Saturn. In 2013, however, astronomers found two rings around Chariklo, an odd little rock about 250 kilometres across between the orbits of Saturn and Uranus. Chiron, one of Chariklo’s neighbours, may also have a ring.

Quote
Ortiz and Santos-Sanz also found that Haumea is slightly larger than once thought: at its widest, it is nearly the diameter of Pluto, the largest-known object orbiting the sun beyond Neptune. It is, however, only about 1025 kilometres across at its narrowest point, less than half Pluto’s diameter.

It is also much less dense than previously thought and has a make-up similar to Pluto’s. Both worlds are mostly rock, surrounded by water ice. And both are shiny, reflecting about half the light that strikes them.

https://www.newscientist.com/article/2150152-distant-dwarf-planet-near-pluto-has-a-ring-that-no-one-expected/amp/

https://youtu.be/TeUegAEbGxo

More here.

http://www.iaa.es/en/news/haumea-most-peculiar-pluto-companions-has-ring-around-it
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/17/2017 07:17 pm
How Bright is the Moon, Really?

Quote
The “inconstant moon,” as Shakespeare called it in Romeo and Juliet, is more reliable than his pair of star-crossed lovers might have thought. Now researchers at the National Institute of Standards and Technology (NIST) plan to make the Moon even more reliable with a new project to measure its brightness.
Scientists put the Moon to work daily as a calibration source for space-based cameras that use the brightness and colors of sunlight reflecting off our planet to track weather patterns, trends in crop health, the locations of harmful algal blooms in oceans and much more. The information sent from Earth-facing imagers allows researchers to predict famines and floods and can help communities plan emergency response and disaster relief.
To make sure that one satellite camera’s “green” isn’t another’s “yellow,” each camera is calibrated—in space—against a common source. The Moon makes a convenient target because, unlike Earth, it has no atmosphere and its surface changes very little.
The trouble is that, for all the songs written about the light of the silvery Moon, it’s still not understood exactly how bright the Moon’s reflected light is, at all times and from all angles. Today’s best measurements allow researchers to calculate the Moon’s brightness with uncertainties of a few percent—not quite good enough for the most sensitive measurement needs, says NIST’s Stephen Maxwell. To make up for these shortcomings, scientists have developed complicated workarounds. For example, they must periodically check the accuracy of their satellite images by making the same measurements multiple ways—from space, from the air and from the ground—simultaneously.
Or, if they want to compare images taken at different times by different satellites, they have to ensure that there is some overlap during their time in space so that the imagers have the chance to measure the same part of the planet at roughly the same time. But what happens if a research team can’t get a new camera into space before an old one is retired? “You get what’s called a data gap, and you lose the ability to stitch together measurements from different satellites to determine long-term trends,” Maxwell says.
Really knowing how bright the Moon is—with uncertainties of much less than 1 percent—would reduce the need for these logistically challenging solutions and ultimately save money.
So NIST is setting out to take new measurements of the Moon’s brightness. Researchers hope they will be the best measurements to date.

https://www.nist.gov/news-events/news/2017/10/how-bright-moon-really
Title: Re: Exoplanets And Stars Thread
Post by: JasonAW3 on 10/17/2017 08:17 pm
Distant dwarf planet near Pluto has a ring that no one expected

Quote
A ring has been found around Haumea, a world more than 2 billion kilometres beyond Pluto. The ring is the most distant ever seen in our solar system.

“This is a landmark discovery,” says Alan Stern at the Southwest Research Institute in Boulder, Colorado. “It’s very exciting.”

Until recently, the only known rings circled giant planets such as Saturn. In 2013, however, astronomers found two rings around Chariklo, an odd little rock about 250 kilometres across between the orbits of Saturn and Uranus. Chiron, one of Chariklo’s neighbours, may also have a ring.

Quote
Ortiz and Santos-Sanz also found that Haumea is slightly larger than once thought: at its widest, it is nearly the diameter of Pluto, the largest-known object orbiting the sun beyond Neptune. It is, however, only about 1025 kilometres across at its narrowest point, less than half Pluto’s diameter.

It is also much less dense than previously thought and has a make-up similar to Pluto’s. Both worlds are mostly rock, surrounded by water ice. And both are shiny, reflecting about half the light that strikes them.

https://www.newscientist.com/article/2150152-distant-dwarf-planet-near-pluto-has-a-ring-that-no-one-expected/amp/

https://www.youtube.com/watch?v=TeUegAEbGxo

More here.

http://www.iaa.es/en/news/haumea-most-peculiar-pluto-companions-has-ring-around-it

It occurs to me to wonder whether or not Huemea may be a fast rotating low density object.

     It could be that the ring is ice that was flung off of the surface of Huemea, during it's "spin-up".  This could have been induced from a glancing strike by a high velocity object impacting its' surface at an angle.

      Otherwise, it might have once been a spherical object, prior to the impact, even allowing for it's low density.
Title: Re: Exoplanets And Stars Thread
Post by: hop on 10/18/2017 03:38 am
A follow up on the Teachey and Kipping exomoon candidate discussed earlier (http://forum.nasaspaceflight.com/index.php?topic=42108.msg1707055#msg1707055).


The nature of the giant exomoon candidate Kepler-1625 b-i (https://arxiv.org/abs/1710.06209) René Heller

(note, submitted not yet reviewed)

Quote
The recent announcement of a Neptune-sized exomoon candidate around the transiting Jupiter-sized object Kepler-1625 b could indicate the presence of a hitherto unknown kind of gas giant moons, if confirmed. Three transits have been observed, allowing radius estimates of both objects. Here we investigate possible mass regimes of the transiting system that could produce the observed signatures and study them in the context of moon formation in the solar system, i.e. via impacts, capture, or in-situ accretion. The radius of Kepler-1625 b suggests it could be anything from a gas giant planet somewhat more massive than Saturn (0.4 M_Jup) to a brown dwarf (BD) (up to 75 M_Jup) or even a very-low-mass star (VLMS) (112 M_Jup ~ 0.11 M_sun). The proposed companion would certainly have a planetary mass. Possible extreme scenarios range from a highly inflated Earth-mass gas satellite to an atmosphere-free water-rock companion of about 180 M_Ear. Furthermore, the planet-moon dynamics during the transits suggest a total system mass of 17.6_{-12.6}^{+19.2} M_Jup. A Neptune-mass exomoon around a giant planet or low-mass BD would not be compatible with the common mass scaling relation of the solar system moons about gas giants. The case of a mini-Neptune around a high-mass BD or a VLMS, however, would be located in a similar region of the satellite-to-host mass ratio diagram as Proxima b, the TRAPPIST-1 system, and LHS 1140 b. The capture of a Neptune-mass object around a 10 M_Jup planet during a close binary encounter is possible in principle. The ejected object, however, would have had to be a super-Earth object, raising further questions of how such a system could have formed. In summary, this exomoon candidate is barely compatible with established moon formation theories. If it can be validated as orbiting a super-Jovian planet, then it would pose an exquisite riddle for formation theorists to solve.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/20/2017 06:09 pm
NOPE, OUR TEMPORARY MOON ISN’T SPACE JUNK, IT’S AN ASTEROID

https://www.universetoday.com/137564/nope-temporary-moon-isnt-space-junk-asteroid/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/23/2017 05:05 pm
The proton and the antiproton are basically identical — indicating that maybe, the universe shouldn’t exist

https://www.zmescience.com/science/physics/proton-antimatter-magnetic-moment-23102017/
Title: Re: Exoplanets And Stars Thread
Post by: JasonAW3 on 10/23/2017 07:12 pm
The proton and the antiproton are basically identical — indicating that maybe, the universe shouldn’t exist

https://www.zmescience.com/science/physics/proton-antimatter-magnetic-moment-23102017/

Interesting question;  Is it possible that what we commonly refer to as "anti-matter" could exist as a non-baryonic form often referred to as Dark Matter?

    If an equal mass of anti-matter were somehow "out of-phase", or more precisely, partially separated from this universe on a separate partial Brane, allowing the mass influences without the direct interaction of matter and anti-matter, would this not account for the absence of anti-matter, Dark Matter itself,  and part of the "missing mass" that appears absent in our universe?
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/24/2017 03:41 pm
Spots On Supergiant Star Drive Spirals In Stellar Wind

https://scienmag.com/spots-on-supergiant-star-drive-spirals-in-stellar-wind/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/24/2017 07:25 pm
The nature of the giant exomoon candidate Kepler-1625 b-i

Quote
The recent announcement of a Neptune-sized exomoon candidate around the transiting Jupiter-sized object Kepler-1625 b could indicate the presence of a hitherto unknown kind of gas giant moons, if confirmed. Three transits have been observed, allowing radius estimates of both objects. Here we investigate possible mass regimes of the transiting system that could produce the observed signatures and study them in the context of moon formation in the solar system, i.e. via impacts, capture, or in-situ accretion. The radius of Kepler-1625 b suggests it could be anything from a gas giant planet somewhat more massive than Saturn (0.4 M_Jup) to a brown dwarf (BD) (up to 75 M_Jup) or even a very-low-mass star (VLMS) (112 M_Jup ~ 0.11 M_sun). The proposed companion would certainly have a planetary mass. Possible extreme scenarios range from a highly inflated Earth-mass gas satellite to an atmosphere-free water-rock companion of about 180 M_Ear. Furthermore, the planet-moon dynamics during the transits suggest a total system mass of 17.6_{-12.6}^{+19.2} M_Jup. A Neptune-mass exomoon around a giant planet or low-mass BD would not be compatible with the common mass scaling relation of the solar system moons about gas giants. The case of a mini-Neptune around a high-mass BD or a VLMS, however, would be located in a similar region of the satellite-to-host mass ratio diagram as Proxima b, the TRAPPIST-1 system, and LHS 1140 b. The capture of a Neptune-mass object around a 10 M_Jup planet during a close binary encounter is possible in principle. The ejected object, however, would have had to be a super-Earth object, raising further questions of how such a system could have formed. In summary, this exomoon candidate is barely compatible with established moon formation theories. If it can be validated as orbiting a super-Jovian planet, then it would pose an exquisite riddle for formation theorists to solve.

https://arxiv.org/abs/1710.06209
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/25/2017 07:31 pm
New article.

Project Blue and the quest to photograph exoplanets

https://phys.org/news/2017-10-blue-quest-exoplanets.amp
Title: Exoplanets And Stars Thread
Post by: Star One on 10/26/2017 07:24 pm
Astronomers discover sunscreen snow falling on hot exoplanet

Quote
Astronomers at Penn State have used the Hubble Space Telescope to find a blistering-hot giant planet outside our solar system where the atmosphere "snows" titanium dioxide -- the active ingredient in sunscreen. These Hubble observations are the first detections of this "snow-out" process, called a "cold trap," on an exoplanet. This discovery, and other observations made by the Penn State team, provide insight into the complexity of weather and atmospheric composition on exoplanets, and may someday be useful for gauging the habitability of Earth-size planets.

http://science.psu.edu/news-and-events/2017-news/Beatty10-2017
Title: Exoplanets And Stars Thread
Post by: Star One on 10/31/2017 04:46 pm
Scientists detect comets outside our solar system

Quote
Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets — comets outside our solar system — orbiting a faint star 800 light years from Earth.
These cosmic balls of ice and dust, which were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized, are some of the smallest objects yet found outside our own solar system.
The discovery marks the first time that an object as small as a comet has been detected using transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Such dips signal potential transits, or crossings of planets or other objects in front of a star, which momentarily block a small fraction of its light. 
In the case of this new detection, the researchers were able to pick out the comet’s tail, or trail of gas and dust, which blocked about one-tenth of 1 percent of the star’s light as the comet streaked by.

http://news.mit.edu/2017/scientists-detect-comets-outside-our-solar-system-1026

We may have found 20 habitable worlds hiding in plain sight

Quote
There could be more habitable planets out there than we thought. An analysis of data from the Kepler space telescope has revealed 20 promising worlds that might be able to host life.

The list of potential worlds includes several planets that orbit stars like our sun. Some take a relatively long time to complete a single orbit, with the longest taking 395 Earth days and others taking Earth weeks or months. The fastest orbit is 18 Earth days. This is very different to the very short “years” we see around smaller stars with habitable planets like Proxima Centauri.

The exoplanet with a 395-day year is one of the most promising worlds for life on the list, says Jeff Coughlin, a Kepler team lead who helped find the potential planets. Called KOI-7923.01, it is 97 per cent the size of Earth, but a little colder.

Its cooler temperature is due to its distance from its star and the fact that the star is slightly cooler than our sun. This means it may be a little more like tundra regions on Earth than temperate ones, but is still warm enough and large enough to hold the liquid water essential to life as we know it.

“If you had to choose one to send a spacecraft to, it’s not a bad option,” says Coughlin.

A solid chance
The team is 70 to 80 per cent certain that these are solid candidates, he says. They can’t be confirmed yet as more observations are needed: the planets all come from the original Kepler mission, which stared at the same region of the sky for only four years before its aiming ability was crippled when its reaction wheels broke in 2013. This means that we have only seen each of these planets once or twice due to their long orbits, and the signals could be a little wobbly.

Ground-based observatories or the Hubble Space Telescope will have to take more observations over the coming years to double-check, Coughlin says.

https://www.newscientist.com/article/may-found-20-habitable-worlds-hiding-plain-sight/

Here’s the paper.

https://arxiv.org/abs/1710.06758
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 10/31/2017 07:59 pm
Exoplanet-Hunting Survey Discovers Three More Giant Alien Worlds!

Quote
From the SuperWASP survey data, Dr. Demangeon and her colleagues were able to detect three transit signals coming from three distant stars – WASP-151, WASP-153 and WASP-156. This was then followed by spectroscopic observations performed using the Haute-Provence Observatory in France and the La Silla Observatory in Chile, which allowed the team to confirm the nature of these planets.

From this, they determined that WASP-151b and WASP-153b are two “hot Saturns”, meaning they are low-density gas giants with close orbits. They orbit their respective suns, which are both early G-type stars (aka. yellow dwarfs, like our Sun), with an orbital period of 4.53 and 3.33 days. WASP-156b, meanwhile, is a Super-Neptune that orbits a K-type (orange dwarf) star.

Quote
Taken together, these planets represent some major opportunities for exoplanet research. As they indicate, “these three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert.” This refers to the boundary astronomers have observed around stars where shot period Neptune-size planets are very unlikely to be found.

Quote
The team also offered some possible explanations for the existence of a “Neptunian desert” based on their findings. For starters, they proposed that a high-eccentricity migration could be responsible, where Neptune-sized ice giants form in the outer reaches of a star system and migrate inward over time. They also indicate that their discovery offers compelling evidence that ultra-violet radiation and gas envelope-depletion could be a key part of the puzzle.

https://www.universetoday.com/137671/exoplanet-hunting-survey-discovers-three-giant-alien-worlds/amp/
Title: Re: Exoplanets And Stars Thread
Post by: jebbo on 11/01/2017 06:40 am
First planet for the "Next Generation Transit Survey" programme.

Quote
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host (Teff=3916+71−63 K) in a P=2.674d orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of 0.812+0.066−0.075 MJ, making it the most massive planet ever discovered transiting an M-dwarf. The radius of the planet is 1.33+0.61−0.33 RJ. Since the transit is grazing, we determine this radius by modelling the data and placing a prior on the density from the population of known gas giant planets. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The host star shows no signs of activity, and the kinematics hint at the star being from the thick disk population. With a deep (2.5%) transit around a K=11.9 host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission spectroscopy.

https://arxiv.org/abs/1710.11099 (https://arxiv.org/abs/1710.11099)
https://arxiv.org/abs/1710.11100 (https://arxiv.org/abs/1710.11100)

Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars. 

--- Tony
Title: Exoplanets And Stars Thread
Post by: Star One on 11/01/2017 11:56 am
First planet for the "Next Generation Transit Survey" programme.

Quote
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host (Teff=3916+71−63 K) in a P=2.674d orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of 0.812+0.066−0.075 MJ, making it the most massive planet ever discovered transiting an M-dwarf. The radius of the planet is 1.33+0.61−0.33 RJ. Since the transit is grazing, we determine this radius by modelling the data and placing a prior on the density from the population of known gas giant planets. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The host star shows no signs of activity, and the kinematics hint at the star being from the thick disk population. With a deep (2.5%) transit around a K=11.9 host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission spectroscopy.

https://arxiv.org/abs/1710.11099 (https://arxiv.org/abs/1710.11099)
https://arxiv.org/abs/1710.11100 (https://arxiv.org/abs/1710.11100)

Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars. 

--- Tony

They were talking about this on BBC Radio 4 this morning and interviewing one of the scientists involved in the discovery.

Wouldn’t one answer by that this was a wandering planet that was captured by this star?
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 11/01/2017 11:05 pm
Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars.

Wouldn’t one answer by that this was a wandering planet that was captured by this star?

It is an answer, but an extremely unlikely one. Not only would such a rogue planet have to come sufficiently near the star - and space is big compared to stars - but capture is not a straightforward process (generally there needs to be a third body of comparable size involved).

An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 11/02/2017 10:44 am
Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars.

Wouldn’t one answer by that this was a wandering planet that was captured by this star?

It is an answer, but an extremely unlikely one. Not only would such a rogue planet have to come sufficiently near the star - and space is big compared to stars - but capture is not a straightforward process (generally there needs to be a third body of comparable size involved).

An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!

The mass estimates put below the minimum for a Brown Dwarf.
Title: Re: Exoplanets And Stars Thread
Post by: clongton on 11/02/2017 03:42 pm
Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars.

Wouldn’t one answer by that this was a wandering planet that was captured by this star?

It is an answer, but an extremely unlikely one. Not only would such a rogue planet have to come sufficiently near the star - and space is big compared to stars - but capture is not a straightforward process (generally there needs to be a third body of comparable size involved).

An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!

The mass estimates put below the minimum for a Brown Dwarf.

The minimum is a yet unproven theorem that may or may not be correct. The more we learn the faster our precious theorems fall by the wayside. It may ultimately prove to be correct but it will be a long, long time before that can occur. Best not to dismiss an idea based on unproven theorems.
Title: Re: Exoplanets And Stars Thread
Post by: jebbo on 11/02/2017 06:01 pm
For a bit of fun, follow the #ExoCup tag on Twitter ... interesting to see the advocacy for people's favourite exoplanets.

And it is actually fun!

--- Tony
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 11/03/2017 04:36 pm
ALMA Discovery of Dust Belts Around Proxima Centauri

Quote
Proxima Centauri, the star closest to our Sun, is known to host at least one terrestrial planet candidate in a temperate orbit. Here we report the ALMA detection of the star at 1.3 mm wavelength and the discovery of a belt of dust orbiting around it at distances ranging between 1 and 4 au, approximately. Given the low luminosity of the Proxima Centauri star, we estimate a characteristic temperature of about 40 K for this dust, which might constitute the dust component of a small-scale analog to our solar system Kuiper belt. The estimated total mass, including dust and bodies up to 50 km in size, is of the order of 0.01 Earth masses, which is similar to that of the solar Kuiper belt. Our data also show a hint of warmer dust closer to the star. We also find signs of two additional features that might be associated with the Proxima Centauri system, which, however, still require further observations to be confirmed: an outer extremely cold (about 10 K) belt around the star at about 30 au, whose orbital plane is tilted about 45 degrees with respect to the plane of the sky; and additionally, we marginally detect a compact 1.3 mm emission source at a projected distance of about 1.2 arcsec from the star, whose nature is still unknown.

https://arxiv.org/abs/1711.00578
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 11/03/2017 10:59 pm
An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!

The mass estimates put below the minimum for a Brown Dwarf.

The minimum is a yet unproven theorem that may or may not be correct. The more we learn the faster our precious theorems fall by the wayside. It may ultimately prove to be correct but it will be a long, long time before that can occur. Best not to dismiss an idea based on unproven theorems.

The definition of a brown dwarf appears to still be subject to debate. Some define it as a sub-stellar object that is massive enough (>~13Mj) to undergo deuterium fusion. On that definition, this object is not a brown dwarf. Others define it as a sub-stellar object that was formed by the collapse of a nebula. I'm not aware of the minimum size of such objects (if any, though gas pressure presumably would overcome gravitational forces at some point?). By that definition this could be a brown dwarf. Given the definitional conflict I tentatively suggested the term 'sub-brown dwarf'! :)

ALMA Discovery of Dust Belts Around Proxima Centauri

I found the tentative possibility of a Saturn analogue (rings and all) to be the most interesting aspect:

Quote
Finally, an exciting alternative scenario is that the source traces a ring of dust surrounding an as yet undiscovered giant planet orbiting at a (projected) distance of 1.6 au (orbital period >~5.8 yr). ... we would expect a planet of mass ∼100 M⊕, the mass of Saturn, to account for the observed 1.3 mm emission. No clear RV signal that would indicate such a planet is present in the data of the long-term monitoring of the star. Further observations are being undertaken to confirm, or rule out this intriguing possibility. At any rate, our study shows that ALMA provides already the necessary sensitivity and resolution to detect rings around exoplanets in alpha Centauri, and perhaps in other nearby stars.
Title: Exoplanets And Stars Thread
Post by: Star One on 11/03/2017 11:01 pm
An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!

The mass estimates put below the minimum for a Brown Dwarf.

The minimum is a yet unproven theorem that may or may not be correct. The more we learn the faster our precious theorems fall by the wayside. It may ultimately prove to be correct but it will be a long, long time before that can occur. Best not to dismiss an idea based on unproven theorems.

The definition of a brown dwarf appears to still be subject to debate. Some define it as a sub-stellar object that is massive enough (>~13Mj) to undergo deuterium fusion. On that definition, this object is not a brown dwarf. Others define it as a sub-stellar object that was formed by the collapse of a nebula. I'm not aware of the minimum size of such objects (if any, though gas pressure presumably would overcome gravitational forces at some point?). By that definition this could be a brown dwarf. Given the definitional conflict I tentatively suggested the term 'sub-brown dwarf'!

ALMA Discovery of Dust Belts Around Proxima Centauri

I found the tentative possibility of a Saturn analogue (rings and all) to be the most interesting aspect:

Quote
Finally, an exciting alternative scenario is that the source traces a ring of dust surrounding an as yet undiscovered giant planet orbiting at a (projected) distance of 1.6 au (orbital period >~5.8 yr). ... we would expect a planet of mass ∼100 M⊕, the mass of Saturn, to account for the observed 1.3 mm emission. No clear RV signal that would indicate such a planet is present in the data of the long-term monitoring of the star. Further observations are being undertaken to confirm, or rule out this intriguing possibility. At any rate, our study shows that ALMA provides already the necessary sensitivity and resolution to detect rings around exoplanets in alpha Centauri, and perhaps in other nearby stars.

If it is anywhere near as big as Saturn that’s another small star with an extremely big planet.

This link posted in the Red Dot thread seems to suggest it isn’t a gas giant.

http://www.astronomy.com/news/2017/11/proxima-rings
Title: Re: Exoplanets And Stars Thread
Post by: Alpha_Centauri on 11/03/2017 11:11 pm
Except the current RV surveys even before the most recent observations have already ruled out such a massive planet at this distance.
Title: Re: Exoplanets And Stars Thread
Post by: Bynaus on 11/04/2017 04:24 pm
The mass of the planet has only been guestimated from a ring-mass-to-planet-mass ratio of 1e-7. Whether it really is a ring, or whether planets with larger mass ratios exist are open questions.

"More work is necessary".
Title: Re: Exoplanets And Stars Thread
Post by: CuddlyRocket on 11/04/2017 07:05 pm
Except the current RV surveys even before the most recent observations have already ruled out such a massive planet at this distance.

Quoting from the paper:
Quote
No clear RV signal that would indicate such a planet is present in the data of the long-term monitoring of the star. Further observations are being undertaken to confirm, or rule out this intriguing possibility.

So, according to them, it's still an open question.
Title: Re: Exoplanets And Stars Thread
Post by: Dao Angkan on 11/06/2017 06:03 pm
Edit: worth noting that this planet puts the cat slightly amongst the planet-formation pigeons as planets this large were not expected around such small stars.

Wouldn’t one answer by that this was a wandering planet that was captured by this star?

It is an answer, but an extremely unlikely one. Not only would such a rogue planet have to come sufficiently near the star - and space is big compared to stars - but capture is not a straightforward process (generally there needs to be a third body of comparable size involved).

An alternative explanation is that this object was formed at the same time as its host star by direct collapse of the nebula - i.e. it's a very small brown dwarf (sub-brown dwarf?). I'm not sure if there are any theoretical minimums for the mass of objects formed by such a mechanism!

According to Shiv S. Kumar (who first theorised Brown Dwarfs in the 1960s) the theoretical minimum mass from cloud collapse is supposedly ~1 MJup, which is close to the mass range for this body (although slightly higher). Incidentally, the theoretical maximum mass from core accretion  in the vicinity of a star of any mass is supposedly ~2 MJup, presumably lower for low mass stars. This object is pretty close to the ~1 MJup limit, so may just be massive enough to have formed by cloud collapse.

The Bottom of the Main Sequence and Beyond: Speculations, Calculations, Observations, and Discoveries (1958-2002) (https://www.cambridge.org/core/services/aop-cambridge-core/content/view/01E697652BC3A1F68E814D1EBF8A6D85/S0074180900210176a.pdf/bottom_of_the_main_sequence_and_beyond_speculations_calculations_observations_and_discoveries_19582002.pdf)

Quote
The Basic Nature of the Stars and Planets

Since  1964,  I  have been presenting arguments to  show that the star formation processes are fundamentally different from those of planet formation (Kumar 1964; Kumar 1967; Kumar 1972a; Kumar 1974; Kumar 1990; Kumar 1995; Kumar 2000a). Stars (including brown dwarfs) are formed by the fragmentation of gaseous clouds, and the mass range in the stellar domain ranges from  a  few hundred solar masses to ~0.001 M☉ (or  ~1 MJup). Planets are formed by the slow accumulation (accretion) of dust, rocks, and gas  in the vicinity of  a star, and the mass range in the planetary domain ranges from ~0.000001 MJup to  ~2 MJup. Thus, as  far  as the masses of the stars and planets are concerned, I'm not talking of just one linear sequence but of  two separate sequences arising from two different formation processes.

The old idea that the stars and planets represent two sections of the same linear sequence (in mass), with objects above a certain mass labeled as stars and objects below that certain mass labeled as planets, is not the correct way  to understand the two groups of objects. The mass of  an object doesn't uniquely determine its basic nature. In order to ascertain the basic nature of an object, we have  to  know its formation mechanism. Theoretically speaking, an object of  1MJup (located somewhere in the Universe) may come into existence by either the star formation processes or the planet formation processes. As I have repeatedly pointed out (Kumar 1972a; Kumar 1974; Kumar 1994; Kumar 1995), the most massive planet in the Solar System (Jupiter) was most probably formed by the planet formation processes and not by the star formation processes. For Jupiter, the presence of  a rocky/metallic core, the chemical composition of its interior, and the chemical compositin of its atmosphere clearly indicate that the planet acquired its present mass  (in the presence of the Sun)  by the slow accretion of dust, rocks, and gas  over the past 4.5  billion years (Kumar 1994; Kumar 1995; Kumar 2000a).  It  does not appear to have been formed by the rapid collapse of an extended, gaseous object of mass  0.001 M☉.
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 11/06/2017 07:15 pm
NuSTAR probes black hole mystery

Quote
Black holes are famous for being ravenous eaters, but they do not eat everything that falls toward them. A small portion of material gets shot back out in powerful jets of hot gas, called plasma, that can wreak havoc on their surroundings. Along the way, this plasma somehow gets energized enough to strongly radiate light, forming two bright columns along the black hole’s axis of rotation. Scientists have long debated where and how this happens in the jet.

Astronomers have new clues to this mystery. Using NASA’s NuSTAR space telescope and a fast camera called ULTRACAM on the William Herschel Observatory in La Palma, Spain, scientists have been able to measure the distance that particles in jets travel before they “turn on” and become bright sources of light. This distance is called the “acceleration zone.” The study is published in the journal Nature Astronomy.

https://astronomynow.com/2017/11/05/nustar-probes-black-hole-mystery/
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 11/07/2017 08:17 pm
Alma’s image of red giant star gives a surprising glimpse of the Sun’s future

Quote
A Chalmers-led team of astronomers has for the first time observed details on the surface of an aging star with the same mass as the Sun. ALMA:s images show that the star is a giant, its diameter twice the size of Earth’s orbit around the Sun, but also that the star’s atmosphere is affected by powerful, unexpected shock waves. The research is published in Nature Astronomy on 30 October 2017.

http://www.chalmers.se/en/researchinfrastructure/oso/news/Pages/Alma-image-of-red-giant-star-gives-a-surprising-glimpse-of-the-Suns-future.aspx
Title: Re: Exoplanets And Stars Thread
Post by: Star One on 11/08/2017 07:48 pm
MSU biologists have found out how long can microorganisms live on Mars

Quote
"The results of the study indicate the possibility of prolonged cryoconservation of viable microorganisms in the Martian regolith. The intensity of ionizing radiation on the surface of Mars is 0.05-0.076 Gy/year and decreases with depth. Taking into account the intensity of radiation in the Mars regolith, the data obtained by us makes it possible to assume that hypothetical Mars ecosystems could be conserved in anabiotic state in the surface layer of regolith (protected from UV rays) for at least 1.3-2 million years, at a depth of two meters for no less than 3.3 million years, and at a depth of five meters for at least 20 million years. The data obtained can also be applied to assess the possibility of detecting viable microorganisms at other objects of the Solar System and within small bodies in outer space" - the scientist added.

The authors have for the first time proven that prokaryotes can survive irradiation with ionizing radiation in doses exceeding 80 kGy. The data obtained indicate both a possible underestimation of the radiation resistance of natural microbial communities and the need to study the joint effect of a set of extraterrestrial and cosmic factors on living organisms and biomolecules in astrobiological model experiments.

https://www.eurekalert.org/pub_releases/2017-11/lmsu-mbh110817.php
Title: Re: Astronomy Thread
Post by: Star One on 11/10/2017 06:36 am
OGLE-2016-BLG-1190Lb: First Spitzer Bulge Planet Lies Near the Planet/Brown-Dwarf Boundary

Quote
We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass M_p= 13.4+-0.9 M_J places it right at the deuterium burning limit, i.e., the conventional boundary between "planets" and "brown dwarfs". Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (low mass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf M_host = 0.89+-0.07 M_sun and the planet has a semi-major axis a~2.0 AU. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultra-dense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.

https://arxiv.org/abs/1710.09974
Title: Re: Astronomy Thread
Post by: Star One on 11/15/2017 05:04 pm
Ross 128 b: A ‘Temperate’ Planet?

Quote
What gives the Ross 128 b detection a wrinkle of astrobiological interest is that the star the planet orbits is relatively inactive. Red dwarfs are known for the flares that can flood nearby planets with ultraviolet and X-ray radiation. Compounded with the fact that habitable zone planets must orbit quite close to a parent M-dwarf (given the star’s small size and low temperature compared to the Sun), such flares could act as a brake on the development of life.

Ross 128 b may thus have a higher likelihood for astrobiological activity than Proxima b, assuming that it actually is in the habitable zone. Right now the team behind this work, led by Xavier Bonfils (Université Grenoble Alpes) hedges its bets by referring to the planet as ‘temperate’ and ‘close to the inner edge of the conventional habitable zone.’

https://www.centauri-dreams.org/?p=38800
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 11/16/2017 05:16 am
Ross 128 b: A ‘Temperate’ Planet?

You can find the paper at A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs (https://www.eso.org/public/archives/releases/sciencepapers/eso1736/eso1736a.pdf)

Quote
(from the abstract) Here we report on our radial velocity observations of Ross 128 (Proxima Virginis, GJ447, HIP 57548), an M4 dwarf just 3.4 parsec away from our Sun. This source hosts an exo-Earth with a projected mass m sin i = 1.35M⊕ and an orbital period of 9.9 days. Ross 128 b receives ∼1.38 times as much flux as Earth from the Sun and its equilibrium ranges in temperature between 269 K for an Earth-like albedo and 213 K for a Venus-like albedo. Recent studies place it close to the inner edge of the conventional habitable zone. An 80-day long light curve from K2 campaign C01 demonstrates that Ross 128 b does not transit. Together with the All Sky Automated Survey (ASAS) photometry and spectroscopic activity indices, the K2 photometry shows that Ross 128 rotates slowly and has weak magnetic activity. In a habitability context, this makes survival of its atmosphere against erosion more likely. Ross 128 b is the second closest known exo-Earth, after Proxima Centauri b (1.3 parsec), and the closest temperate planet known around a quiet star.

Interesting the use of the Kepler K2 data. Not gone unnoticed by the latter :) :

NASA's Kepler/K2 GO Office‏ @KeplerGO
8 hours ago
Did you know?  @NASAKepler observed #Ross128b in 2014!  The discovery paper uses these Kepler data to show that the planet does not transit, and that the host star is magnetically quiet and rotating slowly.  @ESO's #HARPS and @NASA's #K2Mission are a winning combo!
Title: Re: Astronomy Thread
Post by: Star One on 11/16/2017 05:51 am
Ross 128 b: A ‘Temperate’ Planet?

You can find the paper at A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs (https://www.eso.org/public/archives/releases/sciencepapers/eso1736/eso1736a.pdf)

Quote
(from the abstract) Here we report on our radial velocity observations of Ross 128 (Proxima Virginis, GJ447, HIP 57548), an M4 dwarf just 3.4 parsec away from our Sun. This source hosts an exo-Earth with a projected mass m sin i = 1.35M⊕ and an orbital period of 9.9 days. Ross 128 b receives ∼1.38 times as much flux as Earth from the Sun and its equilibrium ranges in temperature between 269 K for an Earth-like albedo and 213 K for a Venus-like albedo. Recent studies place it close to the inner edge of the conventional habitable zone. An 80-day long light curve from K2 campaign C01 demonstrates that Ross 128 b does not transit. Together with the All Sky Automated Survey (ASAS) photometry and spectroscopic activity indices, the K2 photometry shows that Ross 128 rotates slowly and has weak magnetic activity. In a habitability context, this makes survival of its atmosphere against erosion more likely. Ross 128 b is the second closest known exo-Earth, after Proxima Centauri b (1.3 parsec), and the closest temperate planet known around a quiet star.

Interesting the use of the Kepler K2 data. Not gone unnoticed by the latter :) :

NASA's Kepler/K2 GO Office‏ @KeplerGO
8 hours ago
Did you know?  @NASAKepler observed #Ross128b in 2014!  The discovery paper uses these Kepler data to show that the planet does not transit, and that the host star is magnetically quiet and rotating slowly.  @ESO's #HARPS and @NASA's #K2Mission are a winning combo!

It’s frustrating that both this exoplanet & Proxima b do not transit their star’s from our prospective.
Title: Re: Astronomy Thread
Post by: jebbo on 11/16/2017 07:22 am
It’s frustrating that both this exoplanet & Proxima b do not transit their star’s from our prospective.

It certainly makes things harder, but both are very near so all is not lost:
* JWST should be able to get low resolution spectroscopy for Proxima b (good enough to detect CO2 and possibly O3). 
* Direct imaging is very challenging due to the IWA and contrast requirements but there are various proposals that would manage it (free flying star shades etc)

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 11/16/2017 07:23 am
It’s frustrating that both this exoplanet & Proxima b do not transit their star’s from our prospective.

It certainly makes things harder, but both are very near so all is not lost:
* JWST should be able to get low resolution spectroscopy for Proxima b (good enough to detect CO2 and possibly O3). 
* Direct imaging is very challenging due to the IWA and contrast requirements but there are various proposals that would manage it (free flying star shades etc)

--- Tony

Is one of them, even though neither transit, better positioned for observation than the other?
Title: Re: Astronomy Thread
Post by: jebbo on 11/16/2017 07:37 am
Is one of them, even though neither transit, better positioned for observation than the other?

Intuitively I'd say Proxima is easier, purely because it is closer (certainly helps with IWA)

Edit: with a bit of work (a few years), we could get spectra for Proxima b using the VLT.  It needs an upgrade to SPHERE (new coronagraph) and a new fibre feed from the Naysmith A focus to ESPRESSO but it sounds feasible (and fits ESO's strategy of testing instrument for new telescopes on the previous generation).
https://arxiv.org/abs/1609.03082 (https://arxiv.org/abs/1609.03082)

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 11/16/2017 03:21 pm
Is one of them, even though neither transit, better positioned for observation than the other?

Intuitively I'd say Proxima is easier, purely because it is closer (certainly helps with IWA)

Edit: with a bit of work (a few years), we could get spectra for Proxima b using the VLT.  It needs an upgrade to SPHERE (new coronagraph) and a new fibre feed from the Naysmith A focus to ESPRESSO but it sounds feasible (and fits ESO's strategy of testing instrument for new telescopes on the previous generation).
https://arxiv.org/abs/1609.03082 (https://arxiv.org/abs/1609.03082)

--- Tony

Is Ross 128b just a bit to far then for these instruments?
Title: Re: Astronomy Thread
Post by: jebbo on 11/16/2017 03:44 pm
Is Ross 128b just a bit to far then for these instruments?

Yes ... 2.5 times the distance, so smaller inner working angle (sin(IWA) is inversely proportional to distance). Proxima b is already right at the 2lambda/D limit for 750nm.

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 11/16/2017 03:53 pm
Is Ross 128b just a bit to far then for these instruments?

Yes ... 2.5 times the distance, so smaller inner working angle (sin(IWA) is inversely proportional to distance). Proxima b is already right at the 2lambda/D limit for 750nm.

--- Tony

So even in the next decade Ross 128b will escape our grasp so to speak.
Title: Re: Astronomy Thread
Post by: jebbo on 11/16/2017 03:55 pm
No, it's probably in range for the 30m class of telescopes.

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 11/16/2017 04:46 pm
No, it's probably in range for the 30m class of telescopes.

--- Tony

That’s good news then.
Title: Re: Astronomy Thread
Post by: Star One on 11/20/2017 04:23 pm
A Case for an Atmosphere on Super-Earth 55 Cancri e

Quote
One of the primary questions when characterizing Earth-sized and super-Earth-sized exoplanets is whether they have a substantial atmosphere like Earth and Venus or a bare-rock surface like Mercury. Phase curves of the planets in thermal emission provide clues to this question, because a substantial atmosphere would transport heat more efficiently than a bare-rock surface. Analyzing phase-curve photometric data around secondary eclipses has previously been used to study energy transport in the atmospheres of hot Jupiters. Here we use phase curve, Spitzer time-series photometry to study the thermal emission properties of the super-Earth exoplanet 55 Cancri e. We utilize a semianalytical framework to fit a physical model to the infrared photometric data at 4.5 μm. The model uses parameters of planetary properties including Bond albedo, heat redistribution efficiency (i.e., ratio between radiative timescale and advective timescale of the atmosphere), and the atmospheric greenhouse factor. The phase curve of 55 Cancri e is dominated by thermal emission with an eastward-shifted hotspot. We determine the heat redistribution efficiency to be ${1.47}_{-0.25}^{+0.30}$, which implies that the advective timescale is on the same order as the radiative timescale. This requirement cannot be met by the bare-rock planet scenario because heat transport by currents of molten lava would be too slow. The phase curve thus favors the scenario with a substantial atmosphere. Our constraints on the heat redistribution efficiency translate to an atmospheric pressure of ~1.4 bar. The Spitzer 4.5 μm band is thus a window into the deep atmosphere of the planet 55 Cancri e.

http://iopscience.iop.org/article/10.3847/1538-3881/aa9278
Title: Astronomy Thread
Post by: Star One on 11/20/2017 04:53 pm
Giant telescope’s mobile-phone ‘dead zones’ rile South African residents

Quote
Sensitive radio dishes of the Square Kilometre Array will affect phone reception — and could harm local economies, say farmers.

https://www.nature.com/news/giant-telescope-s-mobile-phone-dead-zones-rile-south-african-residents-1.22998
Title: Astronomy Thread
Post by: Star One on 11/20/2017 07:18 pm
Phil Plait debunks the latest moon hoax nonsense and despairs that even Newsweek reproduced these ridiculous claims.

Quote
And it denigrates science. It demeans one of the most amazing challenges humans have ever undertaken, one of the greatest accomplishments in our history.

Perhaps even worse, it's painful to see a magazine like Newsweek promulgate such nonsense. I'll note in the article the writer didn't seek out any expert advice, despite a dozen people who could be found easily using a Google search. I'm one of them, and it took me literally three minutes to figure out exactly what's what in this photo. So yeah, it's irritating (though I'll very grudgingly give Streetcap1 one small piece of credit: He at least links to the original image; most conspiracy theorists don't, which should ring very loud alarm bells).

If there's a lesson to be learned here, it's that this little episode shows how flawed humans can be, how easily we can be swayed by the flimsiest of claims. That is part of our nature… just as it's part of our nature to seek out truth, to investigate the unknown, and to explore it. And while critical thinking and judicious skepticism are harder to implement, and may not be part of our nature, I'll remind you that we invented science. We recognize that we can be fooled, and we created an entire field of thinking and investigation to minimize that issue.

And the beauty is, it works!

After all, for real and for sure, it sent us to the Moon.

http://www.syfy.com/syfywire/no-thats-not-a-stagehand-in-an-apollo-astronaut-photo
Title: Re: Astronomy Thread
Post by: Star One on 11/28/2017 05:15 pm
Seeing Double with K2: Testing Re-inflation with Two Remarkably Similar Planets around Red Giant Branch Stars

Quote
Despite more than 20 years since the discovery of the first gas giant planet with an anomalously large radius, the mechanism for planet inflation remains unknown. Here, we report the discovery of K2-132b, an inflated gas giant planet found with the NASA K2 Mission, and a revised mass for another inflated planet, K2-97b. These planets orbit on ≈9 day orbits around host stars that recently evolved into red giants. We constrain the irradiation history of these planets using models constrained by asteroseismology and Keck/High Resolution Echelle Spectrometer spectroscopy and radial velocity measurements. We measure planet radii of 1.31 ± 0.11 R J and 1.30 ± 0.07 R J, respectively. These radii are typical for planets receiving the current irradiation, but not the former, zero age main-sequence irradiation of these planets. This suggests that the current sizes of these planets are directly correlated to their current irradiation. Our precise constraints of the masses and radii of the stars and planets in these systems allow us to constrain the planetary heating efficiency of both systems as $0.03{ \% }_{-0.02 \% }^{+0.03 \% }$. These results are consistent with a planet re-inflation scenario, but suggest that the efficiency of planet re-inflation may be lower than previously theorized. Finally, we discuss the agreement within 10% of the stellar masses and radii, and the planet masses, radii, and orbital periods of both systems, and speculate that this may be due to selection bias in searching for planets around evolved stars.

http://iopscience.iop.org/article/10.3847/1538-3881/aa932d
Title: Re: Astronomy Thread
Post by: Star One on 11/30/2017 08:56 pm
Subsurface Exolife

Quote
We study the prospects for life on planets with subsurface oceans, and find that a wide range of planets can exist in diverse habitats with relatively thin ice envelopes. We quantify the energy sources available to these worlds, the rate of production of prebiotic compounds, and assess their potential for hosting biospheres. Life on these planets is likely to face challenges, which could be overcome through a combination of different mechanisms. We quantify the number of such worlds, and find that they may outnumber rocky planets in the habitable zone of stars by a few orders of magnitude.

https://arxiv.org/abs/1711.09908
Title: Astronomy Thread
Post by: Star One on 12/01/2017 07:53 pm
Giant black hole pair photobombs Andromeda galaxy

Quote
It seems like even black holes can’t resist the temptation to insert themselves unannounced into photographs. A cosmic photobomb found as a background object in images of the nearby Andromeda galaxy has revealed what could be the most tightly coupled pair of supermassive black holes ever seen.

https://astronomynow.com/2017/12/01/giant-black-hole-pair-photobombs-andromeda-galaxy/

A Microlensing Event Seen from Three Positions in Space

Quote
In a new paper, Yee and a large team of her colleagues report the first microlensing event seen from three well-separated points: Spitzer, the Earth, and the Kepler “K2” mission, which has an orbit similar to that of Spitzer but which currently trails the Earth about one-sixth of the way around in its orbital path. The lensing object, known as MOA-2016-BLG-290, was determined from these measurements to be an extremely low mass star of about .07 solar-masses (seventy-seven Jupiter-masses), and situated about twenty-two thousand light-years away in our galaxy. The result, besides detecting an object intermediate in mass between a star and a planet, demonstrates the power of microlensing parallax measurements predicted decades ago.

https://www.cfa.harvard.edu/news/su201745

The habitability of the Milky Way during the active phase of its central supermassive black hole

Quote
During the peak of their accretion phase, supermassive black holes in galactic cores are known to emit very high levels of ionizing radiation, becoming visible over intergalactic distances as quasars or active galactic nuclei (AGN). Here, we quantify the extent to which the activity of the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*), may have affected the habitability of Earth-like planets in our Galaxy. We focus on the amount of atmospheric loss and on the possible biological damage suffered by planets exposed to X-ray and extreme ultraviolet (XUV) radiation produced during the peak of the active phase of Sgr A*. We find that terrestrial planets could lose a total atmospheric mass comparable to that of present day Earth even at large distances (~1 kiloparsec) from the galactic center. Furthermore, we find that the direct biological damage caused by Sgr A* to surface life on planets not properly screened by an atmosphere was probably significant during the AGN phase, possibly hindering the development of complex life within a few kiloparsecs from the galactic center.

https://arxiv.org/abs/1711.11318
Title: Re: Astronomy Thread
Post by: Star One on 12/05/2017 08:22 pm
Trickle-down is the Solution (to the Planetary Core Formation Problem)

Quote
Scientists have long pondered how rocky bodies in the solar system—including our own Earth—got their metal cores. According to research conducted by The University of Texas at Austin, evidence points to the downwards percolation of molten metal toward the center of the planet through tiny channels between grains of rock.

The finding calls into question the interpretation of prior experiments and simulations that sought to understand how metals behave under intense heat and pressure when planets are forming. Past results suggested that large portions of molten metals stayed trapped in isolated pores between the grains. In contrast, the new research suggests that once those isolated pores grow large enough to connect,  the molten metal starts to flow, and most of it is able to percolate along grain boundaries. This process would let metal trickle down through the mantle, accumulate in the center, and form a metal core, like the iron core at the heart of our home planet.

https://www.jsg.utexas.edu/news/2017/12/trickle-down-is-the-solution-to-the-planetary-core-formation-problem/
Title: Astronomy Thread
Post by: Star One on 12/06/2017 05:54 pm
Researchers find exciting potential for little-known exoplanet – and discover another planet in the process

Quote
New research using data collected by the European Southern Observatory (ESO) has revealed that a little-known exoplanet called K2-18b could well be a scaled-up version of Earth.

Just as exciting, the same researchers also discovered for the first time that the planet has a neighbor.

“Being able to measure the mass and density of K2-18b was tremendous, but to discover a new exoplanet was lucky and equally exciting,” says lead author Ryan Cloutier, a PhD student in U of T Scarborough’s Centre for Planet Science, U of T’s Department of Astronomy and Astrophysics, and Université de Montréal Institute for research on exoplanets (iREx).

Both planets orbit K2-18, a red-dwarf star located about 111 light years away in the constellation Leo. When the planet K2-18b was first discovered in 2015, it was found to be orbiting within the star’s habitable zone, making it an ideal candidate to have liquid surface water, a key element in harbouring conditions for life as we know it.

https://utsc.utoronto.ca/news-events/breaking-research/researchers-find-exciting-potential-little-known-exoplanet-and-discover-another
Title: Re: Astronomy Thread
Post by: Star One on 12/06/2017 08:03 pm
Found: The most distant supermassive black hole ever observed

Quote
A team of astronomers led by Carnegie’s Eduardo Bañados used Carnegie’s Magellan telescopes to discover the most-distant supermassive black hole ever observed. It resides in a luminous quasar and its light reaches us from when the Universe was only 5 percent of its current age — just 690 million years after the Big Bang.

Their findings are published by Nature.

Quasars are tremendously bright objects comprised of enormous black holes accreting matter at the centers of massive galaxies. This newly discovered black hole has a mass that is 800 million times the mass of our Sun.

“Gathering all this mass in fewer than 690 million years is an enormous challenge for theories of supermassive black hole growth,” Bañados explained.

https://astronomynow.com/2017/12/06/found-the-most-distant-supermassive-black-hole-ever-observed/
Title: Re: Astronomy Thread
Post by: jebbo on 12/07/2017 05:20 pm
The E-ELT mirror is now fully funded.

https://www.eso.org/public/announcements/ann17085/?utm_source=Twitter&utm_medium=social&utm_campaign=SocialSignIn (https://www.eso.org/public/announcements/ann17085/?utm_source=Twitter&utm_medium=social&utm_campaign=SocialSignIn)

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 12/12/2017 07:53 pm
Meteorite’s origins point to possible undiscovered asteroid

Quote
A new analysis of a meteorite called Bunburra Rockhole has revealed that the rock originated from a previously unknown parent asteroid, allowing scientists to understand the geology of the parent body.

The parent body was differentiated, meaning that it was large enough to separate into a core, mantle and crust, and was roughly spherical in shape, though not as large as a planet. Identifying a new differentiated asteroid is vital for understanding the formation of asteroids and planets in the Solar System. Most of the large asteroids in the Asteroid Belt are already known, so this means that either the meteorite originated on an asteroid that has been eroded, or there is another large asteroid out there.

Bunburra Rockhole was the first meteorite to be recovered using the Desert Fireball Network, a network of cameras across Australia that observe where meteoroids enter the atmosphere. These cameras make it possible to determine the orbit of a meteorite prior to its descent to Earth. Models of the orbit of Bunburra Rockhole placed its origin within the innermost, main asteroid belt, interior to Vesta, the second-largest body in the Asteroid Belt between Mars and Jupiter.

https://astronomynow.com/2017/12/11/meteorites-origins-point-to-possible-undiscovered-asteroid/
Title: Re: Astronomy Thread
Post by: redliox on 12/12/2017 10:03 pm
Posted an astronomy relevant question in regards to finding out nearest exoplanets:
https://space.stackexchange.com/questions/24010/could-a-21-meter-space-telescope-detect-the-nearest-exoplanets (https://space.stackexchange.com/questions/24010/could-a-21-meter-space-telescope-detect-the-nearest-exoplanets)
Title: Astronomy Thread
Post by: Star One on 12/13/2017 08:01 pm
Amongst the 86 official star names allocated by the IAU Barnard’s Star officially gains that name 100 years after its discovery by Edward Emerson Barnard.

https://www.iau.org/news/pressreleases/detail/iau1707/
Title: Re: Astronomy Thread
Post by: Dao Angkan on 12/13/2017 08:40 pm
Extragalactic exoplanets could be detected by the Large Synoptic Survey Telescope. 

Can gravitational microlensing detect extragalactic exoplanets? Self-lensing models of the Small Magellanic Cloud (https://arxiv.org/abs/1712.03986)

Also, ESPRESSO sees first light (https://www.eso.org/public/news/eso1739/). It should achieve precision of at least an order of magnitude over HARPS.
Title: Re: Astronomy Thread
Post by: redliox on 12/13/2017 10:22 pm
Extragalactic exoplanets could be detected by the Large Synoptic Survey Telescope. 

Can gravitational microlensing detect extragalactic exoplanets? Self-lensing models of the Small Magellanic Cloud (https://arxiv.org/abs/1712.03986)

Also, ESPRESSO sees first light (https://www.eso.org/public/news/eso1739/). It should achieve precision of at least an order of magnitude over HARPS.

Every time I hear about the discovery of some planet 1,000 light years away...I can't help thinking "And we still don't know how many planets are around Alpha Centauri yet."  At least Proxima b makes a start...

I will say finding exoplanets in an entirely different galaxy is impressive.
Title: Re: Astronomy Thread
Post by: Dao Angkan on 12/14/2017 04:16 pm
Detection by radial velocity is probably the best bet for discovering more planets around the Alpha Centauri system and other relatively nearby stars. ESPRESSO and EXPRES (https://arxiv.org/abs/1606.04413) should help with this in the near term.

Microlensing is great for distant stars, currently several exoplanets have been discovered at over 20,000 LY distance. The Small Magellanic Cloud is ~200,000 LY away.
Title: Re: Astronomy Thread
Post by: the_other_Doug on 12/14/2017 10:45 pm
Has anyone come up with what our own sun's radial velocity perturbations would look like from a variety of distances and with a variety of viewing "resolutions"?

In other words, how easy would it be from 30 light-years away, for example, to examine Sol and state that it has four inner rocky planets and four outer gas / ice giants?  How easy from 300?  From 3,000?  Et cetera...
Title: Re: Astronomy Thread
Post by: Alpha_Centauri on 12/15/2017 12:05 pm
Typical angular resolution isn't the problem with RV as you only need an unresolved blob of light. The main limiting factors are things like getting enough photons to flesh out the spectrum (either use a big enough light bucket / telescope / array, or viewing brighter stars), a high enough spectrograph resolution to separate out absorption lines, and the intrinsic "noise" largely due to stellar activity.

Our Sun has a decent luminosity so would be viewable for spectrographs like ours for quite some distance. It is also pretty quiet in comparison to many stars, so I think it would be on any alien astronomers target list. I don't know about exact figures. Of course on the other hand our solar system has one rather big downside; compared with many other systems most of our planets are quite some distance from our star and so have long orbital periods, so monitoring to get large enough orbital arcs to improve S/N would take some time.

I believe radial velocity observations of sunlight were conducted in the past, especially back when people were first thinking about finding planets using RV in the 90s. There will be papers on it somewhere. Obviously our instruments have inmproved significantly since then.
Title: Re: Astronomy Thread
Post by: jebbo on 12/18/2017 11:24 am
Two interesting exoplanet papers today

First, more detail of the "Fulton gap" in planet radii:

Exoplanet Radius Gap Dependence on Host Star Type
Quote
Exoplanets smaller than Neptune are numerous, but the nature of the planet populations in the 1-4 Earth radii range remains a mystery. The complete Kepler sample of Q1-Q17 exoplanet candidates shows a radius gap at ~ 2 Earth radii, as reported by us in January 2017 in LPSC conference abstract #1576 (Zeng et al. 2017). A careful analysis of Kepler host stars spectroscopy by the CKS survey allowed Fulton et al. (2017) in March 2017 to unambiguously show this radius gap. The cause of this gap is still under discussion (Ginzburg et al. 2017; Lehmer & Catling 2017; Owen & Wu 2017). Here we add to our original analysis the dependence of the radius gap on host star type.
https://arxiv.org/abs/1712.05458 (https://arxiv.org/abs/1712.05458)

Second, a study of tidal heating in the TRAPPIST-1 system:

Interior Structures and Tidal Heating in the TRAPPIST-1 Planets
Quote
With seven planets, the TRAPPIST-1 system has the largest number of exoplanets discovered in a single system so far. The system is of astrobiological interest, because three of its planets orbit in the habitable zone of the ultracool M dwarf. Assuming the planets are composed of non-compressible iron, rock, and H2O, we determine possible interior structures for each planet. To determine how much tidal heat may be dissipated within each planet, we construct a tidal heat generation model using a single uniform viscosity and rigidity for each planet based on the planet's composition. With the exception of TRAPPIST-1c, all seven of the planets have densities low enough to indicate the presence of significant H2O in some form. Planets b and c experience enough heating from planetary tides to maintain magma oceans in their rock mantles; planet c may have eruptions of silicate magma on its surface, which may be detectable with next-generation instrumentation. Tidal heat fluxes on planets d, e, and f are lower, but are still twenty times higher than Earth's mean heat flow. Planets d and e are the most likely to be habitable. Planet d avoids the runaway greenhouse state if its albedo is ≳ 0.3. Determining the planet's masses within ∼0.1 to 0.5 Earth masses would confirm or rule out the presence of H2O and/or iron in each planet, and permit detailed models of heat production and transport in each planet. Understanding the geodynamics of ice-rich planets f, g, and h requires more sophisticated modeling that can self-consistently balance heat production and transport in both rock and ice layers.
https://arxiv.org/abs/1712.05641 (https://arxiv.org/abs/1712.05641)

I'm still dubious of the density measurements in this system ... they'll be much more certain once we get RV data from instruments like SPIROU

--- Tony



Title: Re: Astronomy Thread
Post by: Star One on 12/18/2017 07:55 pm
Two interesting exoplanet papers today

First, more detail of the "Fulton gap" in planet radii:

Exoplanet Radius Gap Dependence on Host Star Type
Quote
Exoplanets smaller than Neptune are numerous, but the nature of the planet populations in the 1-4 Earth radii range remains a mystery. The complete Kepler sample of Q1-Q17 exoplanet candidates shows a radius gap at ~ 2 Earth radii, as reported by us in January 2017 in LPSC conference abstract #1576 (Zeng et al. 2017). A careful analysis of Kepler host stars spectroscopy by the CKS survey allowed Fulton et al. (2017) in March 2017 to unambiguously show this radius gap. The cause of this gap is still under discussion (Ginzburg et al. 2017; Lehmer & Catling 2017; Owen & Wu 2017). Here we add to our original analysis the dependence of the radius gap on host star type.
https://arxiv.org/abs/1712.05458 (https://arxiv.org/abs/1712.05458)

Second, a study of tidal heating in the TRAPPIST-1 system:

Interior Structures and Tidal Heating in the TRAPPIST-1 Planets
Quote
With seven planets, the TRAPPIST-1 system has the largest number of exoplanets discovered in a single system so far. The system is of astrobiological interest, because three of its planets orbit in the habitable zone of the ultracool M dwarf. Assuming the planets are composed of non-compressible iron, rock, and H2O, we determine possible interior structures for each planet. To determine how much tidal heat may be dissipated within each planet, we construct a tidal heat generation model using a single uniform viscosity and rigidity for each planet based on the planet's composition. With the exception of TRAPPIST-1c, all seven of the planets have densities low enough to indicate the presence of significant H2O in some form. Planets b and c experience enough heating from planetary tides to maintain magma oceans in their rock mantles; planet c may have eruptions of silicate magma on its surface, which may be detectable with next-generation instrumentation. Tidal heat fluxes on planets d, e, and f are lower, but are still twenty times higher than Earth's mean heat flow. Planets d and e are the most likely to be habitable. Planet d avoids the runaway greenhouse state if its albedo is ≳ 0.3. Determining the planet's masses within ∼0.1 to 0.5 Earth masses would confirm or rule out the presence of H2O and/or iron in each planet, and permit detailed models of heat production and transport in each planet. Understanding the geodynamics of ice-rich planets f, g, and h requires more sophisticated modeling that can self-consistently balance heat production and transport in both rock and ice layers.
https://arxiv.org/abs/1712.05641 (https://arxiv.org/abs/1712.05641)

I'm still dubious of the density measurements in this system ... they'll be much more certain once we get RV data from instruments like SPIROU

--- Tony

First paper listed above comes under criticism for being an example of ‘flag planting’, half finished and not the appropriate forum for discussing the topic.

https://mobile.twitter.com/chrislintott/status/942831019161538561
Title: Re: Astronomy Thread
Post by: jebbo on 12/19/2017 06:27 am
First paper listed above comes under criticism for being an example of ‘flag planting’, half finished and not the appropriate forum for discussing the topic.

Yes, I saw that ... it was a discussion over the purpose of the (extremely new) "Research Notes" rather than a critique of the paper (don't think anyone questioned the data).  To me, leaving aside the flag-planting issue, it seems in the spirit of RN: small contributions that either need follow-up or are not worth a paper in their own right.

The wider discussion surrounding this bit was more interesting: when should effects be named after people.

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 12/19/2017 06:37 am
First paper listed above comes under criticism for being an example of ‘flag planting’, half finished and not the appropriate forum for discussing the topic.

Yes, I saw that ... it was a discussion over the purpose of the (extremely new) "Research Notes" rather than a critique of the paper (don't think anyone questioned the data).  To me, leaving aside the flag-planting issue, it seems in the spirit of RN: small contributions that either need follow-up or are not worth a paper in their own right.

The wider discussion surrounding this bit was more interesting: when should effects be named after people.

--- Tony

Yes I noticed the naming issue. I know Twitter isn’t a very good basis for judging these things but the consensus seemed to be against the naming in this case
Title: Re: Astronomy Thread
Post by: jebbo on 12/19/2017 07:00 am
Yes I noticed the naming issue. I know Twitter isn’t a very good basis for judging these things but the consensus seemed to be against the naming in this case

Yes ... hardly surprising as the whole "Fulton gap" name was really just a bit of a running gag on Twitter.  Photo-evaporation valley is short and descriptive enough.

--- Tony
Title: Re: Astronomy Thread
Post by: as58 on 12/19/2017 07:59 am
I must admit that I don't see the point of RNAAS when everything is put on arxiv anyway. To me it seems like a flag-planting operation by AAS...
Title: Re: Astronomy Thread
Post by: jebbo on 12/20/2017 08:41 am
Predictions of planet detections with near infrared radial velocities in the up-coming SPIRou Legacy Survey-Planet Search
Quote
The SPIRou near infrared spectro-polarimeter is destined to begin science operations at the Canada-France-Hawaii Telescope in mid-2018. One of the instrument's primary science goals is to discover the closest exoplanets to the Solar System by conducting a 3-5 year long radial velocity survey of nearby M dwarfs at an expected precision of ∼1 m s−1; the SPIRou Legacy Survey-Planet Search (SLS-PS). In this study we conduct a detailed Monte-Carlo simulation of the SLS-PS using our current understanding of the occurrence rate of M dwarf planetary systems and physical models of stellar activity. From simultaneous modelling of planetary signals and activity, we predict the population of planets detected in the SLS-PS. With our fiducial survey strategy and expected instrument performance over a nominal survey length of ∼3 years, we expect SPIRou to detect 85.3+29.3−12.4 planets including 20.0+16.8−7.2 habitable zone planets and 8.1+7.6−3.2 Earth-like planets from a sample of 100 M1-M8.5 dwarfs out to 11 pc. By studying mid-to-late M dwarfs previously inaccessible to existing optical velocimeters, SPIRou will put meaningful constraints on the occurrence rate of planets around those stars including the value of η⊕ at an expected level of precision of ≲45%. We also predict a subset of 46.7+16.0−6.0 planets may be accessible with dedicated high-contrast imagers on the next generation of ELTs including 4.9+4.7−2.0 potentially imagable Earth-like planets. Lastly, we compare the results of our fiducial survey strategy to other foreseeable survey versions to quantify which strategy is optimized to reach the SLS-PS science goals. The results of our simulations are made available to the community on github.
https://arxiv.org/abs/1712.06673 (https://arxiv.org/abs/1712.06673)

I'm looking forward to the results from this one!  First, it should give us much better masses for Proxima b and the TRAPPIST-1 planets; second, it should yield a few direct imaging targets for the forthcoming 30m class telescopes.

--- Tony
Title: Astronomy Thread
Post by: Star One on 12/20/2017 08:07 pm
Giant Bubbles on Red Giant Star’s Surface

Quote
Astronomers using ESO’s Very Large Telescope have for the first time directly observed granulation patterns on the surface of a star outside the Solar System — the ageing red giant π1 Gruis. This remarkable new image from the PIONIER instrument reveals the convective cells that make up the surface of this huge star, which has 350 times the diameter of the Sun. Each cell covers more than a quarter of the star’s diameter and measures about 120 million kilometres across. These new results are being published this week in the journal Nature.

http://www.eso.org/public/news/eso1741/

https://youtu.be/L0E8moAlEDk
Title: Astronomy Thread
Post by: Star One on 12/22/2017 07:24 pm
The cool and distant formation of Mars

Quote
With approximately one ninth of Earth's mass, Mars is widely considered to be a stranded planetary embryo that never became a fully-grown planet. A currently popular planet formation theory predicts that Mars formed near Earth and Venus and was subsequently scattered outwards to its present location. In such a scenario, the compositions of the three planets are expected to be similar to each other. However, bulk elemental and isotopic data for martian meteorites demonstrate that key aspects of Mars' composition are markedly different from that of Earth. This suggests that Mars formed outside of the terrestrial feeding zone during primary accretion. It is therefore probable that Mars always remained significantly farther from the Sun than Earth; its growth was stunted early and its mass remained relatively low. Here we identify a potential dynamical pathway that forms Mars in the asteroid belt and keeps it outside of Earth's accretion zone while at the same time accounting for strict age and compositional constraints, as well as mass differences. Our uncommon pathway (approximately 2% probability) is based on the Grand Tack scenario of terrestrial planet formation, in which the radial migration by Jupiter gravitationally sculpts the planetesimal disc at Mars' current location. We conclude that Mars' formation requires a specific dynamical pathway, while this is less valid for Earth and Venus. We further predict that Mars' volatile budget is most likely different from Earth's and that Venus formed close enough to our planet that it is expected to have a nearly identical composition from common building blocks.

http://www.sciencedirect.com/science/article/pii/S0012821X1730184X?via%3Dihub#!

https://arxiv.org/pdf/1704.00184.pdf
Title: Astronomy Thread
Post by: Star One on 12/28/2017 05:05 pm
The origins of our solar system?

Triggered Star Formation inside the Shell of a Wolf–Rayet Bubble as the Origin of the Solar System

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A critical constraint on solar system formation is the high ${}^{26}\mathrm{Al}$/27Al abundance ratio of $5\times {10}^{-5}$ at the time of formation, which was about 17 times higher than the average Galactic ratio, while the 60Fe/56Fe value was about $2\times {10}^{-8}$, lower than the Galactic value. This challenges the assumption that a nearby supernova (SN) was responsible for the injection of these short-lived radionuclides into the early solar system. We show that this conundrum can be resolved if the solar system was formed by a triggered star formation at the edge of a Wolf–Rayet (W–R) bubble. 26Al is produced during the evolution of the massive star, released in the wind during the W–R phase, and condenses into dust grains that are seen around W–R stars. The dust grains survive passage through the reverse shock and the low-density shocked wind, reach the dense shell swept-up by the bubble, detach from the decelerated wind, and are injected into the shell. Some portions of this shell subsequently collapse to form the dense cores that give rise to solar-type systems. The subsequent aspherical SN does not inject appreciable amounts of ${}^{60}\mathrm{Fe}$ into the proto–solar system, thus accounting for the observed low abundance of ${}^{60}\mathrm{Fe}$. We discuss the details of various processes within the model and conclude that it is a viable model that can explain the initial abundances of ${}^{26}\mathrm{Al}$ and ${}^{60}\mathrm{Fe}$. We estimate that 1%–16% of all Sun-like stars could have formed in such a setting of triggered star formation in the shell of a W–R bubble.

http://iopscience.iop.org/article/10.3847/1538-4357/aa992e/meta
Title: Re: Astronomy Thread
Post by: ExoExplorer on 01/03/2018 05:29 pm
Predictions of planet detections with near infrared radial velocities in the up-coming SPIRou Legacy Survey-Planet Search
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The SPIRou near infrared spectro-polarimeter is destined to begin science operations at the Canada-France-Hawaii Telescope in mid-2018. One of the instrument's primary science goals is to discover the closest exoplanets to the Solar System by conducting a 3-5 year long radial velocity survey of nearby M dwarfs at an expected precision of ∼1 m s−1; the SPIRou Legacy Survey-Planet Search (SLS-PS). In this study we conduct a detailed Monte-Carlo simulation of the SLS-PS using our current understanding of the occurrence rate of M dwarf planetary systems and physical models of stellar activity. From simultaneous modelling of planetary signals and activity, we predict the population of planets detected in the SLS-PS. With our fiducial survey strategy and expected instrument performance over a nominal survey length of ∼3 years, we expect SPIRou to detect 85.3+29.3−12.4 planets including 20.0+16.8−7.2 habitable zone planets and 8.1+7.6−3.2 Earth-like planets from a sample of 100 M1-M8.5 dwarfs out to 11 pc. By studying mid-to-late M dwarfs previously inaccessible to existing optical velocimeters, SPIRou will put meaningful constraints on the occurrence rate of planets around those stars including the value of η⊕ at an expected level of precision of ≲45%. We also predict a subset of 46.7+16.0−6.0 planets may be accessible with dedicated high-contrast imagers on the next generation of ELTs including 4.9+4.7−2.0 potentially imagable Earth-like planets. Lastly, we compare the results of our fiducial survey strategy to other foreseeable survey versions to quantify which strategy is optimized to reach the SLS-PS science goals. The results of our simulations are made available to the community on github.
https://arxiv.org/abs/1712.06673 (https://arxiv.org/abs/1712.06673)

I'm looking forward to the results from this one!  First, it should give us much better masses for Proxima b and the TRAPPIST-1 planets; second, it should yield a few direct imaging targets for the forthcoming 30m class telescopes.

--- Tony
SLS-PS is unlikely to detect the radial velocity of TRAPPIST-1 (mv = 19). It's just simply too faint for Doppler spectroscopy.
Title: Re: Astronomy Thread
Post by: jebbo on 01/03/2018 05:39 pm
SLS-PS is unlikely to detect the radial velocity of TRAPPIST-1 (mv = 19). It's just simply too faint for Doppler spectroscopy.

Yes, it is very dim in the V band, but it is much brighter in IR. Also, I didn't post that blind, I asked them ages ago:

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with IR mags of J=11, H=10.7 and K=10.3, Trappist-1 is in reach of SPIRou_astro. no doubt SPIRou_astro will look at it once on CFHT


https://twitter.com/SPIRou_astro/status/836515528474755072 (https://twitter.com/SPIRou_astro/status/836515528474755072)

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W/ expected RV amplitudes of 0.9 to 3.5m/s, Trappist-1 planets b to h may be better characterized in mass & density w/ SPIRou_astro


--- Tony

Title: Re: Astronomy Thread
Post by: ExoExplorer on 01/03/2018 05:53 pm
Typical angular resolution isn't the problem with RV as you only need an unresolved blob of light. The main limiting factors are things like getting enough photons to flesh out the spectrum (either use a big enough light bucket / telescope / array, or viewing brighter stars), a high enough spectrograph resolution to separate out absorption lines, and the intrinsic "noise" largely due to stellar activity.

Our Sun has a decent luminosity so would be viewable for spectrographs like ours for quite some distance. It is also pretty quiet in comparison to many stars, so I think it would be on any alien astronomers target list. I don't know about exact figures. Of course on the other hand our solar system has one rather big downside; compared with many other systems most of our planets are quite some distance from our star and so have long orbital periods, so monitoring to get large enough orbital arcs to improve S/N would take some time.

I believe radial velocity observations of sunlight were conducted in the past, especially back when people were first thinking about finding planets using RV in the 90s. There will be papers on it somewhere. Obviously our instruments have inmproved significantly since then.
The orbital inclination of the alien Earth would also limit the measurable amplitude of wobble. For example, if the inclination is close to 0°, the planet would be undetectable by RV regardless of how precise.
Title: Re: Astronomy Thread
Post by: ExoExplorer on 01/03/2018 06:23 pm
SLS-PS is unlikely to detect the radial velocity of TRAPPIST-1 (mv = 19). It's just simply too faint for Doppler spectroscopy.

Yes, it is very dim in the V band, but it is much brighter in IR. Also, I didn't post that blind, I asked them ages ago:

Quote
with IR mags of J=11, H=10.7 and K=10.3, Trappist-1 is in reach of SPIRou_astro. no doubt SPIRou_astro will look at it once on CFHT


https://twitter.com/SPIRou_astro/status/836515528474755072 (https://twitter.com/SPIRou_astro/status/836515528474755072)

Quote
W/ expected RV amplitudes of 0.9 to 3.5m/s, Trappist-1 planets b to h may be better characterized in mass & density w/ SPIRou_astro


--- Tony
How surprising. I thought it would be impossible in the short-term, but the outer three planets are hardly achievable since low-density materials like ice probably make up a significant part of their masses. Combination of RV and TTV would constrain the whole system with better precision I believe.
Title: Re: Astronomy Thread
Post by: Star One on 01/09/2018 05:00 pm
Extra-Terrestrial Hypatia Stone Rattles Solar System Status Quo

https://scienmag.com/extra-terrestrial-hypatia-stone-rattles-solar-system-status-quo/
Title: Re: Astronomy Thread
Post by: Bynaus on 01/09/2018 06:58 pm
Extra-Terrestrial Hypatia Stone Rattles Solar System Status Quo

https://scienmag.com/extra-terrestrial-hypatia-stone-rattles-solar-system-status-quo/

A couple of years ago, I was co-author on a paper studying the Hypatia stone (https://arxiv.org/abs/1510.06594). The stone is clearly extraterrestrial, yes, but I think this whole story is getting blown way out of proportion in the new paper.

First, its not like carbon-dominated materials are unheard off in meteorites - we identified several possibilities in our paper, the strongest, in my opinion, being that the stone is shock-compressed (thus diamond-bearing) graphite nodule from an iron meteorite (there is actually additional support for this from the Fe, Ni, S and P phases the authors of the new paper report - all these elements are abundant in iron meteorites).

Second, the claim of a pre-solar origin would require the identification of the characteristically large isotopic anomalies, which the authors of the new paper do not report.
Title: Re: Astronomy Thread
Post by: Star One on 01/09/2018 08:13 pm
White dwarf’s inner makeup is mapped for the first time

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Astronomers have probed the inner life of a dead star. Tiny changes in a white dwarf’s brightness reveal that the stellar corpse has more oxygen in its core than expected, researchers report online January 8 in Nature. The finding could challenge theories of how stars live and die, and may have implications for measuring the expansion of the universe.

Quote
More recent observations suggest that these so-called standard candles may not be so standard after all. If the white dwarfs that help create supernovas have varying oxygen contents, that may help explain some of the differences, Fontaine says.

Accounting for that difference may someday help reveal details of what dark energy is made of, says astrophysicist Alexei Filippenko of the University of California, Berkeley. But those implications are a long way off. “Just how much bearing it will have on cosmology remains to be seen,” he says.

https://www.sciencenews.org/article/white-dwarfs-inner-makeup-mapped-first-time
Title: Re: Astronomy Thread
Post by: fthomassy on 01/09/2018 10:38 pm
Cross posting as it might relate to astronomy tracking too ...
Incredible footage of stage sep and the boostback burn.

https://www.youtube.com/watch?v=KjQ41VIaL3Q
Thanks!  That was my video. I'm hoping at some point other launch regulars who do tracking shots start to adopt my setup and software for their shots as well.  The software is very experimental, but it's freely available.  Computer, joystick, and telescope not included, of course.
Title: Re: Astronomy Thread
Post by: Star One on 01/10/2018 07:17 pm
Across the universe, fast radio bursts ‘shout and twist’

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An international group of astronomers has found that the Cornell-discovered fast radio burst FRB 121102 – a brief, gigantic pulse of radio waves from 3 billion light years away – passes through a veil of magnetized plasma. This causes the cosmic blasts to “shout and twist,” which will help the scientists determine the source.

The research is featured on the cover of Nature, Jan. 11.

The “shouting” represents the bursts, and the “twisting” describes a physical phenomenon called Faraday rotation, which occurs as radio waves pass through a magnetized plasma, explained James Cordes, the George Feldstein Professor of Astronomy. Measurement of the twisting provides further scientific detail on the origin of FRB 121102. The data were culled from the Arecibo Observatory in Puerto Rico and confirmed by Green Bank Observatory in West Virginia.

http://news.cornell.edu/stories/2018/01/across-universe-fast-radio-bursts-shout-and-twist
Title: Re: Astronomy Thread
Post by: Star One on 01/11/2018 08:52 pm
The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

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K2-138 is a moderately bright (V = 12.2, K = 10.3) main-sequence K star observed in Campaign 12 of the NASA K2 mission. It hosts five small (1.6–3.3 ${R}_{\oplus }$) transiting planets in a compact architecture. The periods of the five planets are 2.35, 3.56, 5.40, 8.26, and 12.76 days, forming an unbroken chain of near 3:2 resonances. Although we do not detect the predicted 2–5 minute transit timing variations (TTVs) with the K2 timing precision, they may be observable by higher-cadence observations with, for example, Spitzer or CHEOPS. The planets are amenable to mass measurement by precision radial velocity measurements, and therefore K2-138 could represent a new benchmark system for comparing radial velocity and TTV masses. K2-138 is the first exoplanet discovery by citizen scientists participating in the Exoplanet Explorers project on the Zooniverse platform.

http://iopscience.iop.org/article/10.3847/1538-3881/aa9be0
Title: Re: Astronomy Thread
Post by: jebbo on 01/12/2018 09:31 am
The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

Yes, this is a very interesting one: the two transits at ~42 days that suggest a sixth planet are consistent with the 3/2 resonance chain ... if you skip two slots at ~18.6 days and 27.9 days

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 01/12/2018 09:35 am
The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

Yes, this is a very interesting one: the two transits at ~42 days that suggest a sixth planet are consistent with the 3/2 resonance chain ... if you skip two slots at ~18.6 days and 27.9 days

--- Tony

Go and have a quick look at Professor Chris Lintott’s twitter account as he talks about that very thing on there.
Title: Re: Astronomy Thread
Post by: Star One on 01/12/2018 12:53 pm
Meet the amateur astronomers who track secretive spy satellites for fun

https://www.popsci.com/zuma-spy-satellite-amateur-astronomer
Title: Re: Astronomy Thread
Post by: Star One on 01/12/2018 07:36 pm
We may be able to see mountains and valleys on distant worlds

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Moiya McTier at Columbia University in New York presented her research into the embryonic field of exotopography on 11 January at a meeting of the American Astronomical Society. She says that by analysing the dip in a star’s light as a planet passes in front of it, we might be able to discern actual details about the planet’s landscape.

None of the rocky planets in our solar system are perfectly round: there are mountains, canyons, craters and other features that carve elevations high and low across a surface. So why shouldn’t there be similar features on planets orbiting other stars?

McTier took US Geological Survey maps of our four terrestrial planets and the Moon to determine what their light curve around

https://www.newscientist.com/article/2158466-we-may-be-able-to-see-mountains-and-valleys-on-distant-worlds
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 01/13/2018 05:53 pm
The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

Yes, this is a very interesting one: the two transits at ~42 days that suggest a sixth planet are consistent with the 3/2 resonance chain ... if you skip two slots at ~18.6 days and 27.9 days

55.8 days, and any multiple thereof, is a whole number multiple of both 18.6 and 27.9. So, perhaps there's something larger with such an orbital period, but not a multiple of ~42 days, that disrupted the formation of any planets at those two slots? If the orbital period is long enough it might not have transited during the observation run.
Title: Re: Astronomy Thread
Post by: Star One on 01/16/2018 07:33 pm
Ingredients for life revealed in meteorites that fell to Earth

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Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

https://astronomynow.com/2018/01/16/ingredients-for-life-revealed-in-meteorites-that-fell-to-earth/
Title: Re: Astronomy Thread
Post by: jgoldader on 01/16/2018 08:36 pm
Ingredients for life revealed in meteorites that fell to Earth

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Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

https://astronomynow.com/2018/01/16/ingredients-for-life-revealed-in-meteorites-that-fell-to-earth/

I'm pretty sure I remember a while back reading about water from the ancient Earth discovered in salt crystals from fossilized rocks... ah, here it is!

https://www.sciencedaily.com/releases/2001/12/011210163624.htm

This new study looks to be in a similar spirit.  (Boy, it really WAS a while back!)  Awfully interesting stuff.
Title: Re: Astronomy Thread
Post by: Star One on 01/17/2018 08:11 pm
The Third Workshop on Extremely Precise Radial Velocities: The New Instruments

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The Third Workshop on Extremely Precise Radial Velocities was held at the Penn Stater Conference Center and Hotel in State College, Pennsylvania, USA from 2016 August 14 to 17, and featured over 120 registrants from around the world. Here we provide a brief description of the conference, its format, and its session topics and chairs. 23 instrument teams were represented in plenary talks, and we present a table containing the basic characteristics of their new precise Doppler velocimeters.

https://arxiv.org/abs/1801.05383
Title: Astronomy Thread
Post by: Star One on 01/18/2018 07:33 pm
Using Gravitational-wave Observations and Quasi-universal Relations to Constrain the Maximum Mass of Neutron Stars

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Combining the GW observations of merging systems of binary neutron stars and quasi-universal relations, we set constraints on the maximum mass that can be attained by nonrotating stellar models of neutron stars. More specifically, exploiting the recent observation of the GW event GW170817 and drawing from basic arguments on kilonova modeling of GRB 170817A together with the quasi-universal relation between the maximum mass of nonrotating stellar models ${M}_{\mathrm{TOV}}$ and the maximum mass supported through uniform rotation ${M}_{\max }\,=({1.20}_{-0.05}^{+0.02}){M}_{\mathrm{TOV}}$, we set limits for the maximum mass to be ${2.01}_{-0.04}^{+0.04}\leqslant {M}_{\mathrm{TOV}}/{M}_{\odot }\lesssim {2.16}_{-0.15}^{+0.17}$, where the lower limit in this range comes from pulsar observations. Our estimate, which follows a very simple line of arguments and does not rely on the modeling of the electromagnetic signal in terms of numerical simulations, can be further refined as new detections become available. We briefly discuss the impact that our conclusions have on the equation of state of nuclear matter.

http://iopscience.iop.org/article/10.3847/2041-8213/aaa401/meta

New Titan Findings from Topographical Map

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Cassini’s huge dataset will yield discoveries for many years, as witness the global topographical map of Titan that has been assembled by Cornell University astronomers. The map draws on topographical data of the moon from multiple sources by way of studying its terrain and the flow of its surface liquids. Bear in mind that only 9 percent of Titan has been observed at relatively high resolution, and another 25-30 percent at lower resolution. For the remainder, the team mapped the surface using an interpolation algorithm and a global minimization process described in the first of two papers in Geophysical Review Letters.

https://www.centauri-dreams.org/?p=39157
Title: Re: Astronomy Thread
Post by: jebbo on 01/19/2018 07:57 am
Interesting proposal for a large space-based telescope to hunt for biosignatures ... this is the first ESA L4 idea I've seen (might be premature to create an ESA L4 mission competition thread ;) )

Personally, in that time frame, I'd be thinking about on-orbit assembly rather than single fairing-limited launch.

SUPERSHARP - Segmented Unfolding Primary for Exoplanet Research via Spectroscopic High Angular Resolution Photography

Quote
We propose to search for biosignatures in the spectra of reflected light from about 100 Earth-sized planets that are already known to be orbiting in their habitable zones (HZ). For a sample of G and K type hosts, most of these planets will be between 25 and 50 milli-arcsec (mas) from their host star and 1 billion to 10 billion times fainter. To separate the planet's image from that of its host star at the wavelength (763nm) of the oxygen biosignature we need a telescope with an aperture of 16 metres. Furthermore, the intensity of the light from the host star at the position in the image of the exoplanet must be suppressed otherwise the exoplanet will be lost in the glare.
This presents huge technical challenges. The Earth's atmosphere is turbulent which makes it impossible to achieve the required contrast from the ground at 763nm. The telescope therefore needs to be in space and to fit the telescope in the rocket fairing it must be a factor of 4 or more times smaller when folded than when operational. To obtain spectroscopy of the planet's biosignature at 763nm we need to use an integral field spectrometer (IFS) with a field of view (FOV) of 1000 x 1000 milli-arcsec (mas) and a spectral resolution of 100. This is a device that simultaneously takes many pictures of the exoplanet each at a slightly different wavelength which are then recorded as a data cube with two spatial dimensions and one wavelength dimension. In every data cube wavelength slice, the background light from the host star at the location of the planet image must be minimised. This is achieved via a coronagraph which blocks the light from the host star and active/adaptive optics techniques which continuously maintain very high accuracy optical alignment to make the images as sharp as possible. These are the technical challenges to be addressed in a design study.

https://arxiv.org/abs/1801.06111 (https://arxiv.org/abs/1801.06111)

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 01/19/2018 08:48 pm
Neutron star merger yields new puzzle for astrophysicists

https://astronomynow.com/2018/01/19/neutron-star-merger-yields-new-puzzle-for-astrophysicists/
Title: Astronomy Thread
Post by: Star One on 01/23/2018 08:06 pm
Evidence of an Upper Bound on the Masses of Planets and Its Implications for Giant Planet Formation

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Celestial bodies with a mass of $M\approx 10\,{M}_{\mathrm{Jup}}$ have been found orbiting nearby stars. It is unknown whether these objects formed like gas-giant planets through core accretion or like stars through gravitational instability. I show that objects with $M\lesssim 4\,{M}_{\mathrm{Jup}}$ orbit metal-rich solar-type dwarf stars, a property associated with core accretion. Objects with $M\gtrsim 10\,{M}_{\mathrm{Jup}}$ do not share this property. This transition is coincident with a minimum in the occurrence rate of such objects, suggesting that the maximum mass of a celestial body formed through core accretion like a planet is less than $10\,{M}_{\mathrm{Jup}}$. Consequently, objects with $M\gtrsim 10\,{M}_{\mathrm{Jup}}$ orbiting solar-type dwarf stars likely formed through gravitational instability and should not be thought of as planets. Theoretical models of giant planet formation in scaled minimum-mass solar nebula Shakura–Sunyaev disks with standard parameters tuned to produce giant planets predict a maximum mass nearly an order of magnitude larger. To prevent newly formed giant planets from growing larger than $10\,{M}_{\mathrm{Jup}}$, protoplanetary disks must therefore be significantly less viscous or of lower mass than typically assumed during the runaway gas accretion stage of giant planet formation. Either effect would act to slow the Type I/II migration of planetary embryos/giant planets and promote their survival. These inferences are insensitive to the host star mass, planet formation location, or characteristic disk dissipation time.

http://iopscience.iop.org/article/10.3847/1538-4357/aa961c

Medium-sized satellites of large Kuiper belt objects

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While satellites of mid- to small-Kuiper belt objects tend to be similar in size and brightness to their primaries, the largest Kuiper belt objects preferentially have satellites with small fractional brightness. In the two cases where the sizes and albedos of the small faint satellites have been measured, these satellites are seen to be small icy fragments consistent with collisional formation. Here we examine Dysnomia and Vanth, the satellites of Eris and Orcus, respectively. Using the Atacama Large Millimeter Array, we obtain the first spatially resolved observations of these systems at thermal wavelengths. We find a diameter for Dysnomia of 700±115 km and for Vanth of 475+/-75 km, with albedos of 0.04_+0.02_-0.01 and 0.08+/-0.02 respectively. Both Dysnomia and Vanth are indistinguishable from typical Kuiper belt objects of their size. Potential implications for the formation of these types of satellites are discussed.

https://arxiv.org/abs/1801.07221
Title: Re: Astronomy Thread
Post by: Star One on 01/24/2018 04:51 pm
Really like Phil Plait’s writing on this article, he has a really good way of getting things across.

THE STAR HD 4113 IS WAY, *WAY* MORE THAN MEETS THE EYE

http://www.syfy.com/syfywire/the-star-hd-4113-is-way-way-more-than-meets-the-eye
Title: Re: Astronomy Thread
Post by: jebbo on 01/24/2018 05:00 pm
Lol, I'm not a huge fan of his style .. all the gosh wow stuff irritates me. But he does explain things well.

Edit: though I must say HD 4113 deserves the odd gosh, wow ;-)

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 01/24/2018 07:58 pm
Lol, I'm not a huge fan of his style .. all the gosh wow stuff irritates me. But he does explain things well.

Edit: though I must say HD 4113 deserves the odd gosh, wow ;-)

--- Tony

He’s not writing to an informed audience such as yourself but rather Joe Public.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 01/24/2018 08:05 pm
Lol, I'm not a huge fan of his style .. all the gosh wow stuff irritates me. But he does explain things well.

Edit: though I must say HD 4113 deserves the odd gosh, wow ;-)

--- Tony

He’s not writing to an informed audience such as yourself but rather Joe Public.

I'd still rather he'd get the distinction between a name and a designation right (HD 4113 is a designation, not a name). It's a minor thing but it's often those little niggles that annoy! :)
Title: Re: Astronomy Thread
Post by: Star One on 01/24/2018 08:15 pm
More about the TRAPPIST-1 system from a new paper.

Quote
And while we’re talking about M-dwarfs, a new paper is out looking at one of the most interesting systems yet discovered, comprising the seven planets around TRAPPIST-1. Lead author Amy Barr (Planetary Science Institute) and colleagues go to work on the interior structures of these planets as well as their tidal heating and convection given what we know about their mass and radius. The balance between tidal heating and convective transport has implications for the mantles of each planet.

https://www.centauri-dreams.org/?p=39185
Title: Re: Astronomy Thread
Post by: Star One on 01/24/2018 08:47 pm
Astronomers produce first detailed images of surface of giant star

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ATLANTA -- An international team of astronomers has produced the first detailed images of the surface of a giant star outside our solar system, revealing a nearly circular, dust-free atmosphere with complex areas of moving material, known as convection cells or granules, according to a recent study.

The giant star, named π1Gruis, is one of the stars in the constellation Grus (Latin for the crane, a type of bird), which can be observed in the southern hemisphere. An evolved star in the last major phase of life, π1Gruis is 350 times larger than the Sun and resembles what our Sun will become at the end of its life in five billion years. Studying this star gives scientists insight about the future activity, characteristics and appearance of the Sun.

https://www.eurekalert.org/pub_releases/2018-01/gsu-apf012218.php
Title: Re: Astronomy Thread
Post by: Star One on 01/25/2018 08:06 pm
NASA Poised to Topple a Planet-Finding Barrier

NASA optics experts are well on the way to toppling a barrier that has thwarted scientists from achieving a long-held ambition: building an ultra-stable telescope that locates and images dozens of Earth-like planets beyond the solar system and then scrutinizes their atmospheres for signs of life.

Babak Saif and Lee Feinberg at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, have shown for the first time that they can dynamically detect subatomic- or picometer-sized distortions — changes that are far smaller than an atom — across a five-foot segmented telescope mirror and its support structure. Collaborating with Perry Greenfield at the Space Telescope Science Institute in Baltimore, the team now plans to use a next-generation tool and thermal test chamber to further refine their measurements.

The measurement feat is good news to scientists studying future missions for finding and characterizing extrasolar Earth-like planets that potentially could support life.

To find life, these observatories would have to gather and focus enough light to distinguish the planet’s light from that of its much brighter parent star and then be able to dissect that light to discern different atmospheric chemical signatures, such as oxygen and methane. This would require a super-stable observatory whose optical components move or distort no more than 12 picometers, a measurement that is about one-tenth the size of a hydrogen atom.

To date, NASA has not built an observatory with such demanding stability requirements.

How Displacements Occur

Displacements and movement occur when materials used to build telescopes shrink or expand due to wildly fluctuating temperatures, such as those experienced when traveling from Earth to the frigidity of space, or when exposed to fierce launch forces more than six-and-a-half times the force of gravity.

Scientists say that even nearly imperceptible, atomic-sized movements would affect a future observatory’s ability to gather and focus enough light to image and analyze the planet’s light. Consequently, mission planners must design telescopes to picometer accuracies and then test it at the same level across the entire structure, not just between the telescope’s reflective mirrors. Movement occurring at any particular position might not accurately reflect what’s actually happening in other locations.

“These future missions will require an incredibly stable observatory,” said Azita Valinia, deputy Astrophysics Projects Division program manager. “This is one of the highest technology tall poles that future observatories of this caliber must overcome. The team’s success has shown that we are steadily whittling away at that particular obstacle.”

The Initial Test

To carry out the test, Saif and Feinberg used the High-Speed Interferometer, or HSI — an instrument that the Arizona-based 4D Technology developed to measure nanometer-sized dynamic changes in the James Webb Space Telescope’s optical components — including its 18 mirror segments, mounts, and other supporting structures —  during thermal, vibration and other types of environmental testing.

Like all interferometers, the instrument splits light and then recombines it to measure tiny changes, including motion. The HSI can quickly measure dynamic changes across the mirror and other structural components, giving scientists insights into what is happening all across the telescope, not just in one particular spot.

Even though the HSI was designed to measure nanometer or molecule-sized distortions — which was the design standard for Webb — the team wanted to see it could use the same instrument, coupled with specially developed algorithms, to detect even smaller changes over the surface of a spare five-foot Webb mirror segment and its support hardware.

The test proved it could, measuring dynamic movement as small as 25 picometers — about twice the desired target, Saif said.

Next Steps

However, Goddard and 4D Technology have designed a new high-speed instrument, called a speckle interferometer, that allows measurements of both reflective and diffuse surfaces at picometer accuracies. 4D Technology has built the instrument and the Goddard team has begun initial characterization of its performance in a new thermal-vacuum test chamber that controls internal temperatures to a frosty 1-millikelvin.

Saif and Feinberg plan to place test items inside the chamber to see if they can achieve the 12-picometer target accuracy. 

“I think we’ve made a lot of progress. We’re getting there,” Saif said.

For more Goddard technology news, go to https://www.nasa.gov/sites/default/files/atoms/files/
Title: Re: Astronomy Thread
Post by: Star One on 01/27/2018 09:10 pm
Exocomets

Friday, January 26, 2018

Quote
Science Update - A look at CfA discoveries from recent journals
There are currently over 3500 confirmed exoplanets known thanks to the remarkable sensitivity of the Kepler spacecraft and to technological advances in space and ground-based methods made over the past dozen years. Relatively little is known, however, about the minor bodies that might orbit within these systems, asteroids and comets for example. Planet-formation theories predict that such minor bodies should be common, but their low masses and small radii present extreme detection challenges. Methods that rely on solid body transits or velocity variations are generally orders-of-magnitude too weak to spot such small objects. The smallest solid body that has been detected so far via the transit method is an object about one-quarter the size of the Earth, while pulsar timing measurements have spotted a lunar-mass object orbiting a pulsar.

In a tour de force analysis of the Kepler data sets spanning 201250 target stars, CfA astronomers Andrew Vanderburg, Dave Latham, and Allyson Bieryla joined eight of their colleagues in discovering and modeling a likely set of six transiting comets around one star, with another comet possible around a second star. The physical characteristic that made these detections possible was unexpected: the comets have large, extended dust tails that can block enough starlight to make themselves recognizable via unique, asymmetrically shaped absorption dips in their transit lightcurves. (The paper reports, in press, finding a prediction of just such an effect published in 1999). The astronomers systematically consider other explanations for the dips, including starspots, as well as possible inconsistencies in their cometary model, like orbital behavior, but reject them all.

The scientists can estimate the mass of the comets from the observed transit properties and simple assumptions, and they conclude that the bodies are probably similar in mass to Halley's Comet. The scientists also conclude that exocomets are probably not rare given that these seven were spotted without using sophisticated computer tools, although deeper searches will need to be undertaken to find them. Since the two stars hosting exocomets in their study are quite similar in type, they conclude by wondering whether comet transits happen preferentially around certain kinds of stars, although why this might be is not known.

https://www.cfa.harvard.edu/news/su201804
Title: Re: Astronomy Thread
Post by: Hog on 01/29/2018 07:32 pm
Super Blue Blood Moon is scheduled for the Moonrise of the morning of Jan 31st, 2018.

This event wont happen for another 150 years.

It's a Super Moon as it is closer and will appear larger by 14%.  It's a Blue Moon as it is the 2nd full Moon of a calendar month.  And it will appear Red as it all occurring during a Lunar eclipse.


https://www.nasa.gov/feature/super-blue-blood-moon-coming-jan-31
Title: Re: Astronomy Thread
Post by: Star One on 01/29/2018 07:37 pm
The Likelihood of Massive Exomoons

Quote
Are there large moons — perhaps Earth-sized or even bigger — around gas giant planets in habitable zones somewhere in the Milky Way? It’s a wonderful thought given how it multiplies the opportunities for life to find a foothold even in systems much different from our own. Centauri Dreams regular Andrew Tribick recently passed along a new paper that addresses the question in an interesting way, by modeling moon formation and orbital evolution under widely varying conditions of circumplanetary disk composition and evolution.

https://www.centauri-dreams.org/?p=39214
Title: Astronomy Thread
Post by: Star One on 01/30/2018 07:42 pm
HD 4915: A Maunder Minimum Candidate

Quote
We study the magnetic activity cycle of HD 4915 using the \ion{Ca}{2} H \& K emission line strengths measured by Keck I/HIRES spectrograph. The star has been observed as a part of California Planet Search Program from 2006 to present. We note decreasing amplitude in the magnetic activity cycle, a pattern suggesting the star's entry into a Magnetic Grand Minimum (MGM) state, reminiscent of the Sun's Maunder and Dalton Minima. We recommend further monitoring of the star to confirm the grand minimum nature of the dynamo, which would provide insight into the state of the Sun's chromosphere and the global magnetic field during its grand minima. We also recommend continued observations of H \& K emission lines, and ground or space based photometric observations to estimate the sunspot coverage.

https://arxiv.org/abs/1801.09650
Title: Astronomy Thread
Post by: Star One on 02/01/2018 07:41 pm
2004 EW95: A phyllosilicate bearing carbonaceous asteroid in the Kuiper Belt

Quote
Models of the Solar System's dynamical evolution predict the dispersal of primitive planetesimals from their formative regions amongst the gas-giant planets due to the early phases of planetary migration. Consequently, carbonaceous objects were scattered both into the outer asteroid belt and out to the Kuiper Belt. These models predict that the Kuiper Belt should contain a small fraction of objects with carbonaceous surfaces, though to date, all reported visible reflectance spectra of small Kuiper Belt Objects (KBOs) are linear and featureless. We report the unusual reflectance spectrum of a small KBO, (120216) 2004 EW95, which exhibits a large drop in its near-UV reflectance and a broad shallow optical absorption feature centered at ~700 nm. These features, confirmed through multiple epochs of spectral photometry and spectroscopy, have respectively been associated with ferric oxides and phyllosilicates. The spectrum bears striking resemblance to those of some C-type asteroids, suggesting that those objects may share a common origin with 2004 EW95. 2004 EW95 orbits the Sun in a stable mean motion resonance with Neptune, at relatively high eccentricity and inclination, suggesting it may have been emplaced there by some past dynamical instability. These results appear consistent with the aforementioned model predictions and are the first to show a reliably confirmed detection of silicate material on a small KBO.

https://arxiv.org/abs/1801.10163 (https://arxiv.org/abs/1801.10163)

Normal black holes in bulge-less galaxies: the largely quiescent, merger-free growth of black holes over cosmic time

Quote
Understanding the processes that drive the formation of black holes (BHs) is a key topic in observational cosmology. While the observed MBH--MBulge correlation in bulge-dominated galaxies is thought to be produced by major mergers, the existence of a MBH--M⋆ relation, across all galaxy morphological types, suggests that BHs may be largely built by secular processes. Recent evidence that bulge-less galaxies, which are unlikely to have had significant mergers, are offset from the MBH--MBulge relation, but lie on the MBH--M⋆ relation, has strengthened this hypothesis. Nevertheless, the small size and heterogeneity of current datasets, coupled with the difficulty in measuring precise BH masses, makes it challenging to address this issue using empirical studies alone. Here, we use Horizon-AGN, a cosmological hydrodynamical simulation to probe the role of mergers in BH growth over cosmic time. We show that (1) as suggested by observations, simulated bulge-less galaxies lie offset from the main MBH--MBulge relation, but on the MBH--M⋆ relation, (2) the positions of galaxies on the MBH--M⋆ relation are not affected by their merger histories and (3) only ∼35 per cent of the BH mass in today's massive galaxies is directly attributable to merging -- the majority (∼65 per cent) of BH growth, therefore, takes place gradually, via secular processes, over cosmic time.

https://arxiv.org/abs/1801.09699 (https://arxiv.org/abs/1801.09699)
Title: Re: Astronomy Thread
Post by: Star One on 02/01/2018 07:58 pm
Astronomers Find One of the Oldest Stars in the Milky Way

Quote
The formation of the first stars was also what allowed for the creation of heavier elements, and therefore the formation of planets and all life as we know it. However, until now, how and when this process took place has been largely theoretical since astronomers did not know where the oldest stars in our galaxy were to be found. But thanks to a new study by a team of Spanish astronomers, we may have just found the oldest star in the Milky Way!

https://www.universetoday.com/138450/astronomers-find-one-oldest-stars-milky-way/amp/
Title: Astronomy Thread
Post by: Star One on 02/05/2018 05:45 pm
Amazing to detect planets in another galaxy over such a vast distance.

OU Astrophysicists Discover Planets in Extragalactic Galaxies

Quote
NORMAN — A University of Oklahoma astrophysics team has discovered for the first time a population of planets beyond the Milky Way galaxy. Using microlensing—an astronomical phenomenon and the only known method capable of discovering planets at truly great distances from the Earth among other detection techniques—OU researchers were able to detect objects in extragalactic galaxies that range from the mass of the Moon to the mass of Jupiter.

Xinyu Dai, professor in the Homer L. Dodge Department of Physics and Astronomy, OU College of Arts and Sciences, with OU postdoctoral researcher Eduardo Guerras, made the discovery with data from the National Aeronautics and Space Administration’s Chandra X-ray Observatory, a telescope in space that is controlled by the Smithsonian Astrophysical Observatory.

“We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy,” said Dai. “These small planets are the best candidate for the signature we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine the mass.”

While planets are often discovered within the Milky Way using microlensing, the gravitational effect of even small objects can create high magnification leading to a signature that can be modeled and explained in extragalactic galaxies. Until this study, there has been no evidence of planets in other galaxies.

“This is an example of how powerful the techniques of analysis of extragalactic microlensing can be. This galaxy is located 3.8 billion light years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario,” said Guerras. “However, we are able to study them, unveil their presence and even have an idea of their masses. This is very cool science.”

For this study, OU researchers used the NASA Chandra X-ray Observatory at the Smithsonian Astrophysical Observatory. The microlensing models were calculated at the OU Supercomputing Center for Education and Research.

A paper, “Probing Planets in Extragalactic Galaxies Using Quasar Microlensing,” by Dai and Guerras on this study has been published in the Astrophysical Journal Letters. For more information about this research, contact OU Professor Dai at [email protected].

http://ou.edu/publicaffairs/archives/2018/OUAstrophysictsDiscoverPlanetsinExtragalacticGalaxies.html

Probing Planets in Extragalactic Galaxies Using Quasar Microlensing

Quote
Previously, planets have been detected only in the Milky Way galaxy. Here, we show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes. We show that a population of unbound planets between stars with masses ranging from Moon to Jupiter masses is needed to explain the frequent Fek line energy shifts observed in the gravitationally lensed quasar RXJ1131-1231 at a lens redshift of z=0.295 or 3.8 billion light-years away. We constrain the planet mass fraction to be larger than 0.0001 of the halo mass, which is equivalent to 2,000 objects ranging from Moon to Jupiter mass per main sequence star.

https://arxiv.org/abs/1802.00049
Title: Re: Astronomy Thread
Post by: Star One on 02/07/2018 05:15 pm
TRAPPIST-1: Planets Likely Rich in Volatiles

https://www.centauri-dreams.org/2018/02/07/trappist-1-planets-likely-rich-in-volatiles/
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 02/08/2018 10:43 pm
Magellan/PFS Radial Velocities of GJ 9827, a late K dwarf at 30 pc with Three Transiting Super-Earths (https://arxiv.org/abs/1711.01359) (arXiv)

Quote
(Abstract) The Kepler mission showed us that planets with sizes between that of Earth and Neptune appear to be the most common type in our Galaxy. These "super-Earths" continue to be of great interest for exoplanet formation, evolution, and composition studies. However, the number of super-Earths with well-constrained mass and radius measurements remains small (40 planets with σmass< 25\%), due in part to the faintness of their host stars causing ground-based mass measurements to be challenging. Recently, three transiting super-Earth planets were detected by the K2 mission around the nearby star GJ 9827/HIP 115752, at only 30 pc away. The radii of the planets span the "radius gap"' detected by Fulton et al. (2017), and all orbit within ~6.5 days, easing follow-up observations. Here we report radial velocity (RV) observations of GJ 9827, taken between 2010 and 2016 with the Planet Finder Spectrograph on the Magellan II Telescope. We employ two different RV analysis packages, SYSTEMIC and RadVel, to derive masses and thus densities of the GJ 9827 planets. We also test a Gaussian Process regression analysis, but find the correlated stellar noise is not well constrained by the PFS data, and that the GP tends to over fit the RV semi-amplitudes resulting in a lower K value. Our RV observations are not able to place strong mass constraints on the two outer planets (c & d) but do indicate that planet b, at 1.64 R⊕ and ~8 M⊕, is one of the most massive (and dense) super-Earth planets detected to date.
Title: Re: Astronomy Thread
Post by: Star One on 02/13/2018 08:35 pm
Formation of the Earth's inner core is so baffling, scientists say it shouldn't exist

Quote
According to the popular view of the Earth's formation, about one billion years ago, our planet's molten liquid inner core spontaneously began to crystallise, growing rapidly to the extent that it reaches today – around 760 miles in diameter.

However, a new study published in the journal Earth and Planetary Science Letters contradicts this theory, suggesting it is impossible.

http://www.ibtimes.co.uk/formation-earths-inner-core-so-baffling-scientists-say-it-shouldnt-exist-1661119
Title: Re: Astronomy Thread
Post by: Star One on 02/15/2018 07:58 pm
Milky Way no longer ‘little brother’ to Andromeda

Quote
Using a new technique to assess the mass of the Andromeda galaxy, researchers have concluded the giant spiral is not so much a big brother to the Milky Way as it is a near twin.

It has long been thought that Andromeda was two to three times the size of the Milky Way and that Earth’s galaxy would eventually be engulfed during a gravitational close encounter in 5 billion years or so.

https://astronomynow.com/2018/02/15/milky-way-no-longer-little-brother-to-andromeda-researchers-say/
Title: Re: Astronomy Thread
Post by: Star One on 02/15/2018 08:09 pm
Supermassive black hole model predicts characteristic light signals at cusp of collision

A new simulation of supermassive black holes--the behemoths at the centers of galaxies--uses a realistic scenario to predict the light signals emitted in the surrounding gas before the masses collide, said Rochester Institute of Technology researchers.

The RIT-led study represents the first step toward predicting the approaching merger of supermassive black holes using the two channels of information now available to scientists--the electromagnetic and the gravitational wave spectra--known as multimessenger astrophysics. The findings appear in the paper "Quasi-periodic Behavior of Mini-disks in Binary Black Holes Approaching Merger," published in the Astrophysical Journal Letters.

"We've performed the first simulation in which an accretion disk around a binary black hole feeds individual accretion disks, or mini-disks, around each black hole in general relativity and magnetohydrodynamics," said Dennis Bowen, lead author and postdoctoral researcher at RIT's Center for Computational Relativity and Gravitation.

Unlike their less massive cousins, first detected in 2016, supermassive black holes are fed by gas disks that surround them like doughnuts. The strong gravitational pull of the black holes that inspiral toward one another heats and disrupts the flow of gas from disk to black hole and emits periodic signals in the visible to X-ray portions of the electromagnetic spectrum.

"We have not yet seen two supermassive black holes get this close," Bowen said. "It provides the first hints of what these mergers will look like in a telescope. The filling and refilling of mini-disks affect the light signatures."

The simulation models supermassive black holes in a binary pair, each surrounded by its own gas disks. A much larger gas disk encircles the black holes and disproportionately feeds one mini-disk over another, leading to the filling-and-refilling cycle described in the paper.

"The evolution is long enough to study what the real science outcome would look like," said Manuela Campanelli, director of the Center for Computational Relativity and Gravitation and a co-author on the paper.

Binary supermassive black holes emit gravitational waves at lower frequencies than stellar-mass black holes. The ground-based Laser Interferometer Gravitational-wave Observatory, in 2016, detected the first gravitational waves from stellar mass black holes collisions with an instrument tuned to higher frequencies. LIGO's sensitivity is unable to observe the gravitational wave signals produced by supermassive black hole coalescence.

The launch of the space-based Laser Interferometer Space Antenna, or LISA, slated for the 2030s, will detect gravitational waves from colliding supermassive black holes in the cosmos. When operational in the 2020s, the ground-based Large Synoptic Survey Telescope, or LSST, under construction in Cerro Pachón, Chile, will produce the widest, deepest survey of light emissions in the universe. The pattern of signals predicted in the RIT study could guide scientists to orbiting pairs of supermassive black holes.

"In the era of multimessenger astrophysics, simulations such as this are necessary to make direct predictions of electromagnetic signals that will accompany gravitational waves," Bowen said. "This is the first step toward the ultimate goal of simulations capable of making direct predictions of the electromagnetic signal from binary black holes approaching merger."

Bowen and his collaborators combined simulations from RIT's Black Hole Lab computer clusters and the Blue Waters supercomputer at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, one of the largest supercomputers in the United States.

Astrophysicists from RIT, Johns Hopkins University and NASA Goddard Space Flight Center collaborated on the project. The publication is based on Bowen's Ph.D. dissertation at RIT and completes research begun by a co-author, Scott Noble, a former RIT post-doctoral researcher, now at NASA Goddard. Their research is part of a collaborative National Science Foundation-funded project led by Campanelli. Co-authors include Vassilios Mewes, RIT postdoctoral researcher; Miguel Zilhao, former RIT post-doctoral researcher, now at Universidade de Lisboa, in Portugal; and Julian Krolik, professor of physics and astronomy at Johns Hopkins University.

In an upcoming paper, the authors will explore further the correlation between gas flowing in and out of the accretion disks and fluctuating light emissions. They will present predictions of light signatures scientists can expect to see with advanced telescopes when looking for supermassive black holes approaching merger.

https://www.eurekalert.org/pub_releases/2018-02/riot-sbh021418.php
Title: Astronomy Thread
Post by: Star One on 02/16/2018 07:54 pm
New research note.

No Giant Planet Pileup Near 1 au

http://iopscience.iop.org/article/10.3847/2515-5172/aaaebd/meta

Discovery of a Magnetic White Dwarf with Unusual Short-period Variability

Quote
We report the discovery of a magnetic white dwarf which shows periodic variability with P = 110 minutes, color-dependent amplitudes and a transient phase shift in the blue compared to the red lightcurve—a previously unknown type of variability for this type of object. We attribute the variations either to a close ultracool (thus far undetected) companion or, more likely, to magnetic spots with unusual temperature structure.

The object SDSS 160357.93+140929.97 (hereafter SDSS 16+14) was identified as a magnetic white dwarf in Kepler et al. (2013), with an effective temperature of 10,123 K ands a magnetic field strength of 43 MG. We monitored this target on 2015 May 3 and June 5, each time over a time period of 3 hr, using the optical camera EFOSC2 at the ESO/NTT (program 095.D-0245). The g-band lightcurves shows a photometric period of ~100 minutes, with a min–max amplitude of ~3% (compared to a photometric noise of 1%–2%).7

http://iopscience.iop.org/article/10.3847/2515-5172/aaadbf
Title: Re: Astronomy Thread
Post by: Star One on 02/19/2018 08:23 pm
The starry sky shows nocturnal animals the way

Quote
Nocturnal animals can use the stars and the Milky Way to find their way during the darkest hours. While animal navigation is studied all over the world, some of the leading researchers are based at Lund University in Sweden. In a recent article they sum up the research so far and give their thoughts on challenges to come.

https://www.lunduniversity.lu.se/article/the-starry-sky-shows-nocturnal-animals-the-way
Title: Re: Astronomy Thread
Post by: Star One on 02/20/2018 07:44 pm
Astronomers Observe The Rotating Accretion Disk Around The Supermassive Black Hole In M77

https://www.universetoday.com/138589/astronomers-observe-rotating-accretion-disk-around-supermassive-black-hole-m77/
Title: Re: Astronomy Thread
Post by: Star One on 02/22/2018 08:47 am
An amateur astronomer accidentally caught an exploding star on camera—and it gets better

Quote
Victor Buso was looking forward to testing his new camera on September 20, 2016. The locksmith and amateur astronomer waited for nightfall and headed out to his rooftop observatory in the city of Rosario, Argentina, where his 15.7 inch (40 cm) Newtonian telescope was waiting. He had no idea he would help capture the start of one of the most unpredictable events in the universe; a supernova.

https://www.popsci.com/amateur-astronomer-photographs-birth-supernova
Title: Re: Astronomy Thread
Post by: IRobot on 02/22/2018 10:33 am
An amateur astronomer accidentally caught an exploding star on camera—and it gets better

Having worked for several years in the "amateur" astronomy market making CCD cameras, I find it harder and harder to call these people "amateurs". Especially one like this, owning a 16inch scope.
They spend tens of thousands of dollars, sometimes hundreds of thousands of dollars and they make some remarkable things, considering that they are not working full time, most of them don't have the technical or theoretical background and they work most of the times from sub urban locations.

I even know some who do yearly calibrations of professional telescopes!

Among several achievements, they have done:
- discoveries of supernovas
- discoveries of exoplanets
- discoveries of nebulae or nebulae sub-structures
- rocket launch and satellite tracking
- long lost IMAGE sattelite
- independent confirmations of known phenomenons

The last point is important. One argument against conspiracy theories (flat earth, moon landing deniers, UFOs,...) is that amateur astronomers, being independent, keep disproving these wacky theories.
Title: Re: Astronomy Thread
Post by: Star One on 02/22/2018 07:36 pm
Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at Redshift Two

Quote
Abstract
We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift $z\approx 2$. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope supplementing the DES data. Spectroscopic observations confirm DES16C2nm to be at z = 1.998, and spectroscopically similar to Gaia16apd (a SLSN-I at z = 0.102), with a peak absolute magnitude of $U=-22.26\pm 0.06$. The high redshift of DES16C2nm provides a unique opportunity to study the ultraviolet (UV) properties of SLSNe-I. Combining DES16C2nm with 10 similar events from the literature, we show that there exists a homogeneous class of SLSNe-I in the UV (${\lambda }_{\mathrm{rest}}\approx 2500$ Å), with peak luminosities in the (rest-frame) U band, and increasing absorption to shorter wavelengths. There is no evidence that the mean photometric and spectroscopic properties of SLSNe-I differ between low ($z\lt 1$) and high redshift ($z\gt 1$), but there is clear evidence of diversity in the spectrum at ${\lambda }_{\mathrm{rest}}\lt 2000\,\mathring{\rm A} $, possibly caused by the variations in temperature between events. No significant correlations are observed between spectral line velocities and photometric luminosity. Using these data, we estimate that SLSNe-I can be discovered to z = 3.8 by DES. While SLSNe-I are typically identified from their blue observed colors at low redshift ($z\lt 1$), we highlight that at $z\gt 2$ these events appear optically red, peaking in the observer-frame z-band. Such characteristics are critical to identify these objects with future facilities such as the Large Synoptic Survey Telescope, Euclid, and the Wide-field Infrared Survey Telescope, which should detect such SLSNe-I to z = 3.5, 3.7, and 6.6, respectively.

http://iopscience.iop.org/article/10.3847/1538-4357/aaa126/meta
Title: Re: Astronomy Thread
Post by: Star One on 02/22/2018 08:23 pm
Some black holes erase your past

Quote
In the real world, your past uniquely determines your future. If a physicist knows how the universe starts out, she can calculate its future for all time and all space.

But a UC Berkeley mathematician has found some types of black holes in which this law breaks down. If someone were to venture into one of these relatively benign black holes, they could survive, but their past would be obliterated and they could have an infinite number of possible futures.

http://news.berkeley.edu/2018/02/20/some-black-holes-erase-your-past/
Title: Re: Astronomy Thread
Post by: eeergo on 02/24/2018 12:14 pm
https://www.nature.com/articles/nature25151


An "amateur" Argentinian astronomer from Rosario has observed, for the first time, the start of a supernova (IIb) explosion, confirming theoretical models.


http://www.agenciasinc.es/Multimedia/Fotografias/Un-astronomo-aficionado-capta-una-supernova-en-directo (in Spanish)
Title: Re: Astronomy Thread
Post by: Star One on 02/25/2018 08:21 am
https://www.nature.com/articles/nature25151


An "amateur" Argentinian astronomer from Rosario has observed, for the first time, the start of a supernova (IIb) explosion, confirming theoretical models.


http://www.agenciasinc.es/Multimedia/Fotografias/Un-astronomo-aficionado-capta-una-supernova-en-directo (in Spanish)

See post #341 in this thread.
Title: Re: Astronomy Thread
Post by: missinglink on 02/26/2018 08:33 am
Formation of the Earth's inner core is so baffling, scientists say it shouldn't exist

Quote
According to the popular view of the Earth's formation, about one billion years ago, our planet's molten liquid inner core spontaneously began to crystallise, growing rapidly to the extent that it reaches today – around 760 miles in diameter.

However, a new study published in the journal Earth and Planetary Science Letters contradicts this theory, suggesting it is impossible.

http://www.ibtimes.co.uk/formation-earths-inner-core-so-baffling-scientists-say-it-shouldnt-exist-1661119
Only one way to settle this once and for all ... a giant power drill made of pure diamond to carry a determined crew into the beating heart of the planet ... and back out again on the other side.
Title: Astronomy Thread
Post by: Star One on 02/27/2018 08:13 pm
These results seemingly confirm that the expansion of the universe has accelerated since its early days.

Precise New Measurements From Hubble Confirm the Accelerating Expansion of the Universe. Still no Idea Why it’s Happening

https://www.universetoday.com/138663/precise-new-measurements-hubble-confirm-accelerating-expansion-universe-still-no-idea-happening/amp/

Beaming with the Light of Millions of Suns

Quote
In the 1980s, researchers began discovering extremely bright sources of X-rays in the outer portions of galaxies, away from the supermassive black holes that dominate their centers. At first, the researchers thought these cosmic objects—called ultraluminous X-ray sources, or ULXs—were hefty black holes with more than 10 times the mass of the sun. But observations beginning in 2014 from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) and other space telescopes are showing that some ULXs, which glow with X-ray light equal in energy to millions of suns, are actually neutron stars—the burnt-out cores of massive stars that exploded. Three such ULXs have been identified as neutron stars so far.

http://m.caltech.edu/news/beaming-light-millions-suns-81447

When do aging brown dwarfs sweep the clouds away?

Quote
Astronomers measure temperature at which brown dwarfs go from cloudy to cloudless

https://www.eurekalert.org/pub_releases/2018-02/cifs-wda022618.php
Title: Astronomy Thread
Post by: Star One on 02/28/2018 07:51 pm
It’s not often that an astronomy story is the headline news story on a UK national newspaper website. Even a broadsheet like The Guardian.

Cosmic dawn: astronomers detect signals from first stars in the universe

Quote
’Revolutionary’ observations suggest the first stars appeared 180m years after the big bang – and may hold information on dark matter

https://www.theguardian.com/science/2018/feb/28/cosmic-dawn-astronomers-detect-signals-from-first-stars-in-the-universe

https://www.youtube.com/watch?v=wU6KXoO0NEE

And here’s the relevant paper.

An absorption profile centred at 78 megahertz in the sky-averaged spectrum

After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz1. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions2. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected. Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude3. The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.

https://www.nature.com/articles/nature25792

And here’s the second related paper.

Possible interaction between baryons and dark-matter particles revealed by the first stars

The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-α radiation from some of the earliest stars1,2,3,4. By observing this 21-centimetre signal—either its sky-averaged spectrum5 or maps of its fluctuations, obtained using radio interferometers6,7—we can obtain information about cosmic dawn, the era when the first astrophysical sources of light were formed. The recent detection of the global 21-centimetre spectrum5 reveals a stronger absorption than the maximum predicted by existing models, at a confidence level of 3.8 standard deviations. Here we report that this absorption can be explained by the combination of radiation from the first stars and excess cooling of the cosmic gas induced by its interaction with dark matter8,9,10. Our analysis indicates that the spatial fluctuations of the 21-centimetre signal at cosmic dawn could be an order of magnitude larger than previously expected and that the dark-matter particle is no heavier than several proton masses, well below the commonly predicted mass of weakly interacting massive particles. Our analysis also confirms that dark matter is highly non-relativistic and at least moderately cold, and primordial velocities predicted by models of warm dark matter are potentially detectable. These results indicate that 21-centimetre cosmology can be used as a dark-matter probe.

https://www.nature.com/articles/nature25791
Title: Re: Astronomy Thread
Post by: Star One on 02/28/2018 08:07 pm
The moon formed inside a vaporized Earth synestia

Quote
A new explanation for the Moon's origin has it forming inside the Earth when our planet was a seething, spinning cloud of vaporized rock, called a synestia. The new model led by researchers at the University of California, Davis and Harvard University resolves several problems in lunar formation and is published Feb. 28 in the Journal of Geophysical Research - Planets.

https://www.eurekalert.org/pub_releases/2018-02/uoc--tmf022718.php
Title: Astronomy Thread
Post by: Star One on 02/28/2018 08:51 pm
A Potentially Game-Changing Message from the Dawn of Time

https://blogs.scientificamerican.com/observations/a-potentially-game-changing-message-from-the-dawn-of-time/ (https://blogs.scientificamerican.com/observations/a-potentially-game-changing-message-from-the-dawn-of-time/)

More here.

Did Dark Matter Make The Early Universe Chill Out?

https://www.npr.org/sections/thetwo-way/2018/02/28/588833582/did-dark-matter-make-the-early-universe-chill-out
Title: Re: Astronomy Thread
Post by: catdlr on 03/01/2018 08:53 am
Want to See Space? Why Not Use One of NASA's Telescopes From the Comfort of Your Own Home

article: https://www.yahoo.com/news/want-see-space-why-not-155751923.html

Site: http://mo-www.harvard.edu/cgi-bin/OWN/Own.pl

Quote
Each of the telescopes can be operated remotely and do not require a human operator. They are capable of viewing the moon, the Orion Nebula or nearby planets and are even powerful enough to snap a picture of other galaxies.
Title: Astronomy Thread
Post by: Star One on 03/02/2018 08:37 pm
HUBBLE OBSERVES EXOPLANET ATMOSPHERE IN MORE DETAIL THAN EVER BEFORE [HEIC1804]

01 March 2018
An international team of scientists has used the NASA/ESA Hubble Space Telescope to study the atmosphere of the hot exoplanet WASP-39b. By combining this new data with older data they created the most complete study yet of an exoplanet atmosphere. The atmospheric composition of WASP-39b hints that the formation processes of exoplanets can be very different from those of our own Solar System giants.

Investigating exoplanet atmospheres can provide new insight into how and where planets form around a star. "We need to look outward to help us understand our own Solar System," explains lead investigator Hannah Wakeford from the University of Exeter in the UK and the Space Telescope Science Institute in the USA.
Therefore the British-American team combined the capabilities of the NASA/ESA Hubble Space Telescope with those of other ground- and space-based telescopes for a detailed study of the exoplanet WASP-39b. They have produced the most complete spectrum of an exoplanet's atmosphere possible with present-day technology [1].
WASP-39b is orbiting a Sun-like star, about 700 light-years from Earth. The exoplanet is classified as a "Hot-Saturn", reflecting both its mass being similar to the planet Saturn in our own Solar System and its proximity to its parent star. This study found that the two planets, despite having a similar mass, are profoundly different in many ways. Not only is WASP-39b not known to have a ring system, it also has a puffy atmosphere that is free of high-altitude clouds. This characteristic allowed Hubble to peer deep into its atmosphere.
By dissecting starlight filtering through the planet's atmosphere [2] the team found clear evidence for atmospheric water vapour. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers had predicted they would see water vapour, they were surprised by the amount that they found. This surprise, combined with the water abundance allowed to infer the presence of large amount of heavier elements in the atmosphere. This in turn suggests that the planet was bombarded by a lot of icy material which gathered in its atmosphere. This kind of bombardment would only be possible if WASP-39b formed much further away from its host star than it is right now.
"WASP-39b shows exoplanets are full of surprises and can have very different compositions than those of our Solar System," says co-author David Sing from the University of Exeter, UK.
The analysis of the atmospheric composition and the current position of the planet indicate that WASP-39b most likely underwent an interesting inward migration, making an epic journey across its planetary system. "Exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that's fantastic!", adds Wakeford.
Having made its incredible inward journey WASP-39b is now eight times closer to its parent star, WASP-39, than Mercury is to the Sun and it takes only four days to complete an orbit. The planet is also tidally locked, meaning it always shows the same side to its star. Wakeford and her team measured the temperature of WASP-39b to be a scorching 750 degrees Celsius. Although only one side of the planet faces its parent star, powerful winds transport heat from the bright side around the planet, keeping the dark side almost as hot.
"Hopefully this diversity we see in exoplanets will help us figure out all the different ways a planet can form and evolve," explains David Sing.
Looking ahead, the team wants to use the NASA/ESA/CSA James Webb Space Telescope – scheduled to launch in 2019 – to capture an even more complete spectrum of the atmosphere of WASP-39b. James Webb will be able to collect data about the planet's atmospheric carbon, which absorbs light of longer wavelengths than Hubble can see [3]. Wakeford concludes: "By calculating the amount of carbon and oxygen in the atmosphere, we can learn even more about where and how this planet formed."
NOTES
[1] Data used to produce the full spectrum was also collected by NASA's Spitzer Space Telescope and ESO's Very Large Telescope. In addition older data from Hubble were used.
[2] When starlight passes through the atmosphere of an exoplanet, it interacts with the atoms and molecules in it. This leaves a weak fingerprint of the atmosphere in the spectrum of the star. Certain peaks and troughs in the resulting spectrum correspond to specific atoms and molecules, allowing scientists to see exactly what gases make up the atmosphere.
[3] Given the large amount of heavy elements in WASP-39b's atmosphere, Wakeford and her team predict that carbon dioxide will be the dominant form of carbon. This could be measured at a wavelength of 4.5 micrometres with James Webb's NIRSpec instrument. Such follow-up investigations would allow further constraints to be placed on the ratio of carbon to oxygen, and on the metallicity of WASP-39b's atmosphere.
MORE INFORMATION
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

http://sci.esa.int/hubble/60022-hubble-observes-exoplanet-atmosphere-in-more-detail-than-ever-before-heic1804/
Title: Re: Astronomy Thread
Post by: Star One on 03/02/2018 08:44 pm
A Stellar System with Three Super Earths
Friday, March 2, 2018
Science Update - A look at CfA discoveries from recent journals
Over 3500 extra-solar planets have been confirmed to date. Most of them were discovered using the transit method, and astronomers can combine the transit light curves with velocity wobble observations to determine the planet's mass and radius, and thereby constrain its interior structure. The atmosphere can also be studied in a transit by using the fact that the chemical composition of the atmosphere means its opacity varies with wavelength. By measuring the depth of the transit at different wavelengths, it is possible to infer the composition and temperature of the planet's atmosphere.

CfA astronomers Joseph Rodriguez, Andrew Vanderburg, Jason Eastman, David Latham, and Samuel Quinn and their team of scientists discovered three small transiting planets orbiting the star GJ9827 which lies at the relatively close distance of 100 light-years. The three exoplanets have radii of about 1.6, 1.3, and 2.1 Earth-radii respectively. All of them are categorized as super-Earths, that is, with masses that are larger than Earth’s but less than Neptune's. (Radial velocity measurements of the exoplanets, not included in this paper, have just been separately published and confirm this conclusion.)

GJ9827 is one of the few known stars to have multiple transiting terrestrial-sized exoplanets that are suited for atmospheric characterization. In fact, its three exoplanets are particularly interesting because two of them have radii between 1.5 and 2.0 Earth-radii. Across this range in radii, the composition of planets is expected to change from rocky to gaseous; moreover, there are relatively few such candidates for study. These planets orbit very close to the star, with periods of 1.2, 3.6 and 6.2 days respectively, and at these close distances they have fairly hot temperatures, estimated at 1172, 811 and 680 degrees kelvin. Future observations will probe their atmospheres and provide a much more detailed picture of this unusual family of super-Earths.

Reference(s):
"A System of Three Super Earths Transiting the Late K-Dwarf GJ 9827 at 30 pc," Joseph E. Rodriguez, Andrew Vanderburg, Jason D. Eastman, Andrew W. Mann, Ian J. M. Crossfield, David R. Ciardi, David W. Latham, and Samuel N. Quinn, AJ 155, 72, 2018.

https://www.cfa.harvard.edu/news/su201809
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/03/2018 10:02 pm
Yeah, I mentioned this paper on 8 February (Reply #333) with a link to the paper on arXiv (not a criticism, it's nearly a month ago and its difficult to remember everything!). Here's the link again: Magellan/PFS Radial Velocities of GJ 9827, a late K dwarf at 30 pc with Three Transiting Super-Earths (https://arxiv.org/abs/1711.01359)

It seems that this 'radii gap' (sometimes referred to as the Fulton gap) is becoming more firmly established!
Title: Re: Astronomy Thread
Post by: Star One on 03/05/2018 07:36 pm
DONOR STAR BREATHES LIFE INTO ZOMBIE COMPANION

ESA's INTEGRAL space observatory has witnessed a rare event: the moment that winds emitted by a swollen red giant star revived its slow-spinning companion, the core of a dead star, bringing it back to life in a flash of X-rays.

The X-ray flare was first detected by INTEGRAL on 13 August 2017 from an unknown source in the direction of the crowded centre of our Milky Way. The sudden detection triggered a slew of follow-up observations in the following weeks to pin down the culprit.
The observations revealed a strongly magnetised and slowly rotating neutron star that had likely just begun to feed on material from a neighbouring red giant star.
Stars the mass of our Sun, and up to eight times more massive, evolve into red giants towards the end of their lives. Their outer layers puff up and expand millions of kilometres, their dusty, gassy shells blown away from the central star in relatively slow winds up to few hundreds of km/s.
Even larger stars, up to 25–30 times more massive than the Sun, race through their fuel and explode in a supernova, sometimes leaving behind a spinning stellar corpse with a strong magnetic field, known as a neutron star. This tiny core packs the mass of nearly one and half Suns into a sphere only 10 km across, making them some of the densest celestial objects known.

It is not uncommon to find stars paired together, but the new system of a neutron star and red giant is a particularly rare breed known as a 'symbiotic X-ray binary', with no more than 10 known.
"INTEGRAL caught a unique moment in the birth of a rare binary system," says Enrico Bozzo from University of Geneva and lead author of the paper that describes the discovery. "The red giant released a sufficiently dense slow wind to feed its neutron star companion, giving rise to high-energy emission from the dead stellar core for the first time."
The pairing is certainly peculiar. ESA's XMM-Newton and NASA's NuSTAR space telescopes showed that the neutron star spins almost every two hours – very slow compared with other neutron stars, which can spin up to many times per second. Then, the first measurement of the magnetic field of such a neutron star revealed it to be surprisingly strong.
A strong magnetic field typically points to a young neutron star – the magnetic field is thought to fade over time – while a red giant is much older, making it a bizarre couple to have grown up together.
"These objects are puzzling," says Enrico. "It might be that either the neutron star magnetic field does not decay substantially with time after all, or the neutron star actually formed later in the history of the binary system. That would mean it collapsed from a white dwarf into a neutron star as a result of feeding off the red giant over a long time, rather than becoming a neutron star as a result of a more traditional supernova explosion of a short-lived massive star."
With a young neutron star and an old red giant, at some point the winds travelling from the puffed-up giant will begin to rain on to the smaller star, slowing its spin and emitting X-rays.
"We haven't seen this object before in the past 15 years of our observations with INTEGRAL, so we believe we saw the X-rays turning on for the first time," says Erik Kuulkers, ESA's INTEGRAL project scientist. "We'll continue to watch how it behaves in case it is just a long 'burp' of winds, but so far we haven't seen any significant changes."
NOTES FOR EDITORS
"IGR J17329-2731: The birth of a symbiotic X-ray binary," by E. Bozzo et al. is accepted for publication in Astronomy & Astrophysics.
The rapid response of the follow-up observations was enabled by the SmartNet community. This included important contributions from ESA's XMM-Newton and NASA’s NuSTARand Swift space telescopes, and the ground-based Southern Astrophysical Research Telescope, Faulkes Telescopes North and South and the Las Cumbres Observatory.

http://sci.esa.int/integral/60029-donor-star-breathes-life-into-zombie-companion/
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/06/2018 01:35 am
Konstantin Batygin has a new paper out. Here's the Caltech release:

Massive Astrophysical Objects Governed by Subatomic Equation
The Schrödinger Equation makes an unlikely appearance at the astronomical scale (http://www.caltech.edu/news/massive-astrophysical-objects-governed-subatomic-equation-81517)

The paper itself can be found here (pdf):

Schrodinger evolution of self-gravitating discs (https://authors.library.caltech.edu/85094/1/sty162.pdf)

Quote
(Abstract)
An understanding of the long-term evolution of self-gravitating discs ranks among the classic outstanding problems of astrophysics. In this work, we show that the secular inclination dynamics of a geometrically thin quasi-Keplerian disc, with a surface density profile that scales as the inverse square-root of the orbital radius, are described by the time-dependent Schrodinger equation. Within the context of this formalism, nodal bending waves correspond to the eigenmodes of a quasi-particle’s wavefunction, confined in an infinite square well with boundaries given by the radial extent of the disc. We further show that external secular perturbations upon self-gravitating discs exhibit a mathematical similarity to quantum scattering theory. Employing this framework, we derive an analytic criterion for the gravitational rigidity of a nearly-Keplerian disc under external perturbations. Applications of the theory to circumstellar discs and Galactic nuclei are discussed.

As you might expect from one of Konstantin's papers, it's a bit mathematical!
Title: Re: Astronomy Thread
Post by: Star One on 03/07/2018 08:37 am
Massive Astrophysical Objects Governed by Subatomic Equation

Quote
The Schrödinger Equation makes an unlikely appearance at the astronomical scale

Quantum mechanics is the branch of physics governing the sometimes-strange behavior of the tiny particles that make up our universe. Equations describing the quantum world are generally confined to the subatomic realm—the mathematics relevant at very small scales is not relevant at larger scales, and vice versa. However, a surprising new discovery from a Caltech researcher suggests that the Schrödinger Equation—the fundamental equation of quantum mechanics—is remarkably useful in describing the long-term evolution of certain astronomical structures.

http://m.caltech.edu/news/massive-astrophysical-objects-governed-subatomic-equation-81517
Title: Re: Astronomy Thread
Post by: Star One on 03/07/2018 07:24 pm
eso1809 — Photo Release

ALMA Reveals Inner Web of Stellar Nursery

New data from the Atacama Large Millimeter/submillimeter Array (ALMA) and other telescopes have been used to create this stunning image showing a web of filaments in the Orion Nebula. These features appear red-hot and fiery in this dramatic picture, but in reality are so cold that astronomers must use telescopes like ALMA to observe them.

This spectacular and unusual image shows part of the famous Orion Nebula, a star formation region lying about 1350 light-years from Earth. It combines a mosaic of millimetre-wavelength images from the Atacama Large Millimeter/submillimeter Array (ALMA) and the IRAM 30-metre telescope, shown in red, with a more familiar infrared view from the HAWK-I instrument on ESO’s Very Large Telescope, shown in blue. The group of bright blue-white stars at the upper-left is the Trapezium Cluster — made up of hot young stars that are only a few million years old.

The wispy, fibre-like structures seen in this large image are long filaments of cold gas, only visible to telescopes working in the millimetre wavelength range. They are invisible at both optical and infrared wavelengths, making ALMA one of the only instruments available for astronomers to study them. This gas gives rise to newborn stars — it gradually collapses under the force of its own gravity until it is sufficiently compressed to form a protostar — the precursor to a star.

The scientists who gathered the data from which this image was created were studying these filaments to learn more about their structure and make-up. They used ALMA to look for signatures of diazenylium gas, which makes up part of these structures. Through doing this study, the team managed to identify a network of 55 filaments.

The Orion Nebula is the nearest region of massive star formation to Earth, and is therefore studied in great detail by astronomers seeking to better understand how stars form and evolve in their first few million years. ESO’s telescopes have observed this interesting region multiple times, and you can learn more about previous discoveries here, here, and here.

This image combines a total of 296 separate individual datasets from the ALMA and IRAM telescopes, making it one of the largest high-resolution mosaics of a star formation region produced so far at millimetre wavelengths [1].

Notes
[1] Earlier mosaics of Orion at millimetre wavelengths had used single-dish telescopes, such as APEX. The new observations from ALMA and IRAM use interferometry to combine the signals from multiple, widely-separated antennas to create images showing much finer detail.

http://www.eso.org/public/news/eso1809/
Title: Re: Astronomy Thread
Post by: Star One on 03/08/2018 11:07 am
Enceladus and the Conditions for Life

https://youtu.be/T6b9e6DuCew
Title: Re: Astronomy Thread
Post by: Star One on 03/08/2018 08:22 pm
A PECULIAR GALACTIC CLASH [HEIC1805]

Quote
Galaxies are not static islands of stars – they are dynamic and ever-changing, constantly on the move through the darkness of the Universe. Sometimes, as seen in this spectacular Hubble image of Arp 256, galaxies can collide in a crash of cosmic proportions.

http://sci.esa.int/hubble/60037-a-peculiar-galactic-clash-heic1805/
Title: Re: Astronomy Thread
Post by: Star One on 03/09/2018 07:20 pm
The HR 4796A Debris System: Discovery of Extensive Exo-ring Dust Material

The optically and IR-bright and starlight-scattering HR 4796A ringlike debris disk is one of the most- (and best-) studied exoplanetary debris systems. The presence of a yet-undetected planet has been inferred (or suggested) from the narrow width and inner/outer truncation radii of its r = 1farcs05 (77 au) debris ring. We present new, highly sensitive Hubble Space Telescope (HST) visible-light images of the HR 4796A circumstellar debris system and its environment over a very wide range of stellocentric angles from 0farcs32 (23 au) to ≈15'' (1100 au). These very high-contrast images were obtained with the Space Telescope Imaging Spectrograph (STIS) using six-roll PSF template–subtracted coronagraphy suppressing the primary light of HR 4796A, with three image-plane occulters, and simultaneously subtracting the background light from its close angular proximity M2.5V companion. The resulting images unambiguously reveal the debris ring embedded within a much larger, morphologically complex, and biaxially asymmetric exo-ring scattering structure. These images at visible wavelengths are sensitive to and map the spatial distribution, brightness, and radial surface density of micron-size particles over 5 dex in surface brightness. These particles in the exo-ring environment may be unbound from the system and interacting with the local ISM. Herein, we present a new morphological and photometric view of the larger-than-prior-seen HR 4796A exoplanetary debris system with sensitivity to small particles at stellocentric distances an order of magnitude greater than has previously been observed.

http://iopscience.iop.org/article/10.3847/1538-3881/aaa3f3/pdf
Title: Re: Astronomy Thread
Post by: Star One on 03/09/2018 07:42 pm
3 NASA Satellites Recreate Solar Eruption in 3-D

The more solar observatories, the merrier: Scientists have developed new models to see how shocks associated with coronal mass ejections, or CMEs, propagate from the Sun — an effort made possible only by combining data from three NASA satellites to produce a much more robust mapping of a CME than any one could do alone.

Much the way ships form bow waves as they move through water, CMEs set off interplanetary shocks when they erupt from the Sun at extreme speeds, propelling a wave of high-energy particles. These particles can spark space weather events around Earth, endangering spacecraft and astronauts.

Understanding a shock’s structure — particularly how it develops and accelerates — is key to predicting how it might disrupt near-Earth space. But without a vast array of sensors scattered through space, these things are impossible to measure directly. Instead, scientists rely upon models that use satellite observations of the CME to simulate the ensuing shock’s behavior.

https://youtu.be/_Ds6UPbYrwg

Using data from three different satellites, scientists have developed new models that recreate, in 3-D, CMEs and shocks, separately. This movie illustrates the recreation of a CME and shock that erupted from the Sun on March 7, 2011. The pink lines show the CME structure and the yellow lines show the structure of the shock - a side effect of the CME that can spark space weather events around Earth.
Credits: NASA’s Goddard Space Flight Center/GMU/APL/Joy Ng
Download this video in HD formats from NASA Goddard's Scientific Visualization Studio


The scientists — Ryun-Young Kwon, a solar physicist at George Mason University in Fairfax, Virginia, and Johns Hopkins University Applied Physics Laboratory, or APL, in Laurel, Maryland, and APL astrophysicist Angelos Vourlidas — pulled observations of two different eruptions from three spacecraft: ESA/NASA’s Solar and Heliospheric Observatory, or SOHO, and NASA’s twin Solar Terrestrial Relations Observatory, or STEREO, satellites. One CME erupted in March 2011 and the second, in February 2014.

The scientists fit the CME data to their models — one called the “croissant” model for the shape of nascent shocks, and the other the “ellipsoid” model for the shape of expanding shocks — to uncover the 3-D structure and trajectory of each CME and shock.

Each spacecraft’s observations alone weren’t sufficient to model the shocks. But with three sets of eyes on the eruption, each of them spaced nearly evenly around the Sun, the scientists could use their models to recreate a 3-D view. Their work confirmed long-held theoretical predictions of a strong shock near the CME nose and a weaker shock at the sides.

In time, shocks travel away from the Sun, and thanks to the 3-D information, the scientists could reconstruct their journey through space. The modeling helps scientists deduce important pieces of information for space weather forecasting — in this case, for the first time, the density of the plasma around the shock, in addition to the speed and strength of the energized particles. All of these factors are key to assessing the danger CMEs present to astronauts and spacecraft. Their results are summarized in a paper published in the Journal of Space Weather and Space Climate published on Feb. 13, 2018.
Title: Re: Astronomy Thread
Post by: Star One on 03/13/2018 08:25 pm
VOLCANIC WORMHOLE

Quote
The organic and intricate features of a volcanic cave come alive in great detail in this three-dimensional image of La Cueva de Los Verdes in Lanzarote, Spain. Some of the most innovative scanning technologies have produced the largest 3D scan of a lava tube on Earth.

Lava tubes are planetary caves. Similar cave systems have been found from orbit on the Moon and Mars. These underground formations could one day provide safe habitats for humans on other celestial bodies – they provide constant temperature and a good shelter against cosmic radiation and micrometeorites.

Understanding the origins and formation of these caves on Earth is a passage for simulating the future of planetary explorers across the Solar System.

A team of speleologists from the University of Padova, Italy mapped the main path of the cave system aided by ESA astronaut Matthias Mauer. The image covers a 1.3 km section of the lava tube with an unprecedented resolution of few centimetres.

http://m.esa.int/spaceinimages/Images/2018/03/Volcanic_wormhole
Title: Re: Astronomy Thread
Post by: Star One on 03/15/2018 05:56 am
We Just Caught The Strongest-Ever Fast Radio Burst, But They're Still Super Mysterious

Quote
Three more of the mysterious fast radio burst (FRB) signals have been detected this month, and one of them is a real record-breaker, coming in with the highest signal-to-noise ratio ever recorded. That makes it the "brightest" FRB that's ever been observed.


The signals came in on March 1, March 9 (that's the really bright one) and March 11, snagged by the Parkes Observatory radio telescope in remote Australia.

They are called FRB 180301, FRB 180309 and FRB 180311, following the fast radio burst convention of being named for the dates on which they occurred.

https://www.sciencealert.com/brightest-fast-radio-burst-ever-detected-parkes-observatory-frb-180309
Title: Re: Astronomy Thread
Post by: Star One on 03/15/2018 07:55 pm
New instrument built to search for Earth-like exo-planets

Quote
Yale University astronomers have developed a powerful new spectrometer to search for Earth-size planets around nearby stars. Expected to improve precision over earlier ground-based instruments by a factor of 10, the Extreme Precision Spectrometer – EXPRES – is now in operation at the Lowell Observatory’s Discovery Channel Telescope in Arizona.

https://astronomynow.com/2018/03/14/new-instrument-built-to-search-for-earth-like-exo-planets/
Title: Re: Astronomy Thread
Post by: Star One on 03/15/2018 08:12 pm
Mystery of Purple Lights in Sky Solved With Help From Citizen Scientists

https://youtu.be/wRHwGD-is9U

https://www.nasa.gov/feature/goddard/2018/mystery-of-purple-lights-in-sky-solved-with-help-from-citizen-scientists
Title: Re: Astronomy Thread
Post by: Star One on 03/18/2018 08:27 pm
Thought the astronomers on here might appreciate the sentiments expressed on this Twitter thread.

https://twitter.com/AstroKatie/status/975396463625867264?s=20

Quote
This thread might be interesting if you’ve ever wondered: “Could the govt be hiding knowledge of a killer asteroid from us?” Answer is no: we’d all be talking about it on Twitter. (Thread is about worrisome object that, with more data, turned out NOT to be a threat.)
Title: Re: Astronomy Thread
Post by: Star One on 03/18/2018 08:32 pm
Didn’t want to start a new thread yet for this news.

https://twitter.com/jeff_foust/status/975410163481022464?s=20

Quote
NASA has changed its mind and will allow proposals for its next Discovery competition to use RTGs, according to an email sent late yesterday:
Title: Re: Astronomy Thread
Post by: redliox on 03/19/2018 01:58 am
Didn’t want to start a new thread yet for this news.

https://twitter.com/jeff_foust/status/975410163481022464?s=20

Quote
NASA has changed its mind and will allow proposals for its next Discovery competition to use RTGs, according to an email sent late yesterday:

Good news although it'd probably fit better into the Discovery or New Frontiers threads.
Title: Re: Astronomy Thread
Post by: Star One on 03/19/2018 07:32 pm
A Changing Landscape at Ceres

Quote
Ceres turns out to be a livelier place than we might have imagined. Continuing analysis of data from the Dawn spacecraft is showing us an object where surface changes evidently caused by temperature variations induced by the dwarf planet’s orbit are readily visible even in short time frames. Two new papers on the Dawn data are now out in Science Advances, suggesting variations in the amount of surface ice as well as newly exposed crustal material.

https://www.centauri-dreams.org/2018/03/19/a-changing-landscape-at-ceres/
Title: Re: Astronomy Thread
Post by: Star One on 03/20/2018 08:32 pm
Measuring White Dwarf Masses with Gravitational Lensing

Friday, March 16, 2018

Science Update - A look at CfA discoveries from recent journals

Measuring the mass of a celestial body is one of the most challenging tasks in observational astronomy. The most successful method uses binary systems because the orbital parameters of the system depend on the two masses. In the case of black holes, neutron stars, and white dwarfs, the end states of stellar evolution, many are isolated objects, and most of them are also very faint. As a result, astronomers still do not know the distribution of their masses. They are of great interest, however, because they participate in dramatic events like the accretion of material and emission of energetic radiation, or in mergers that can result in gravitational waves, gamma-ray bursts, or Type Ia supernovae, all of which depend on an object's mass.

CfA astronomers Alexander Harding, Rosanne Di Stefano, and Claire Baker and three colleagues propose a new method for determining the masses of isolated compact objects: gravitational lensing. The path of a light beam will be bent by the presence of mass, an effect calculated by General Relativity. A massive body will act like a lens to distort the image of an object seen behind it when the two are close to being aligned along our line-of-sight, and the specifics of the image distortions will depend on the body's mass. The astronomers describe the prospects for predicting lensing events generated by nearby compact objects as their motions take them across the field of background stars.

The team estimates that the nearby population of compact objects contains about 250 neutron stars, 5 black holes, and about 35,000 white dwarf stars suitable for this study. Knowing the general motions of the white dwarfs across the sky, they obtain a statistical estimate of about 30-50 lensing events per decade that could be spotted by Hubble, ESA's Gaia mission, or NASA's new JWST telescope. The next step in this effort is to use ongoing stellar surveys like that of Gaia to refine the bodies' positions and motions to be able to predict specifically which objects to monitor for lensing.

Reference(s):
"Predicting Gravitational Lensing by Stellar Remnants," Alexander J. Harding, R. Di Stefano, S. Lepine, J. Urama, D. Pham and C. Baker, MNRAS 475, 79, 2018.

https://www.cfa.harvard.edu/news/su201811
Title: Re: Astronomy Thread
Post by: Star One on 03/21/2018 08:09 pm
K2-231 b: A sub-Neptune exoplanet transiting a solar twin in Ruprecht 147

Quote
We identify a sub-Neptune exoplanet (Rp=2.5±0.2 R⊕) transiting a solar twin in the Ruprecht 147 star cluster (3 Gyr, 300 pc, [Fe/H] = +0.1 dex). The ~81 day light curve for EPIC 219800881 (V = 12.71) from K2 Campaign 7 shows six transits with a period of 13.84 days, a depth of ~0.06%, and a duration of ~4 hours. Based on our analysis of high-resolution MIKE spectra, broadband optical and NIR photometry, the cluster parallax and interstellar reddening, and isochrone models from PARSEC, Dartmouth, and MIST, we estimate the following properties for the host star: M⋆=1.01±0.03 M⊙, R⋆=0.95±0.03 R⊙, and Teff=5695±50 K. This star appears to be single, based on our modeling of the photometry, the low radial velocity variability measured over nearly ten years, and Keck/NIRC2 adaptive optics imaging and aperture-masking interferometry. Applying a probabilistic mass-radius relation, we estimate that the mass of this planet is Mp=7+5−3 M⊕, which would cause a RV semi-amplitude of K=2±1 m s−1 that may be measurable with existing precise RV facilities. After statistically validating this planet with BLENDER, we now designate it K2-231 b, making it the second sub-stellar object to be discovered in Ruprecht 147 and the first planet; it joins the small but growing ranks of 23 other planets found in open clusters.

https://arxiv.org/abs/1803.07430
Title: Re: Astronomy Thread
Post by: Star One on 03/21/2018 08:28 pm
Evidence that a star disturbed prehistory solar system comets

Quote
About 70,000 years ago, during human occupation of the planet, a small, reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter.

Quote
Now, two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time nearly 340 solar system objects with hyperbolic orbits (very open V-shaped, rather than elliptical) They have concluded that the trajectories of some of these were influenced by the passage of Scholz's star.

"Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come," explains Carlos de la Fuente Marcos, a co-author of the study now published in Monthly Notices of the Royal Astronomical Society.

"In principle," he adds, "one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud. However, what we find is very different—a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz's star."

I love this thought of seeing another red star so bright in the sky.

Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp

Title: Re: Astronomy Thread
Post by: as58 on 03/21/2018 09:22 pm
Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp

Only if human ancestors had much more sensitive eyes than we do. Even at its closest approach the star would have been fainter than 10th magnitude.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/22/2018 05:28 am
Evidence that a star disturbed prehistory solar system comets

Here's the paper on arXiv:

Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies (https://arxiv.org/pdf/1802.00778.pdf)
Title: Astronomy Thread
Post by: Star One on 03/22/2018 06:51 am
Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp

Only if human ancestors had much more sensitive eyes than we do. Even at its closest approach the star would have been fainter than 10th magnitude.

All the articles I’ve seen about this have reported the same thing so I assume it had come from an official press release somewhere?

Especially odd as I’ve looked into this and you’re completely correct, it’s apparent magnitude would have been 11.4 - too faint to be seen with the naked eye.
Title: Re: Astronomy Thread
Post by: jebbo on 03/22/2018 07:05 am
All the articles I’ve seen about this have reported the same thing so I assume it had come from an official press release somewhere?

I think it comes from the final line of the release from the Spanish Foundation for Science & Technology:

Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

Article here (https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.html)

It's well worth reading Eric Mamajek's FAQ for the initial discovery in 2015: here (http://www.pas.rochester.edu/~emamajek/flyby.html)

--- Tony
Title: Re: Astronomy Thread
Post by: Bynaus on 03/22/2018 11:49 am
As I read this, the only thing that might have been visible are the (potential) occasional flares.
Title: Re: Astronomy Thread
Post by: Star One on 03/22/2018 07:56 pm
As I read this, the only thing that might have been visible are the (potential) occasional flares.

Here’s some more thoughts on this topic

Quote
Scholz’s Star is a binary system, a red dwarf orbited by a brown dwarf, and it is likely that there was a time when our ancestors could see it in the sky. But only barely — Eric Mamajek has pointed out that even at its closest approach, the apparent magnitude would have been in the range of 11.4, which is five magnitudes fainter than what the naked eye can see, even in the pristine skies of paleolithic Earth. What might have been visible would have been flares from the M-dwarf, which could have created short-lived transient events, fleeting but noticeable.

https://www.centauri-dreams.org/2018/03/22/a-prehistoric-close-pass/
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/23/2018 07:02 pm
It is likely that human ancestors saw its faint reddish light during prehistorical nights.

Technically correct, but misleading. And in a press release too - who would'a thunk it? :)
Title: Re: Astronomy Thread
Post by: Star One on 03/23/2018 07:33 pm
Hubble Solves Cosmic 'Whodunit' with Interstellar Forensics

Quote
Winner Declared in Tug-of-War Between Two Satellite Galaxies of the Milky Way

In a cosmic tug-of-war between two dwarf galaxies orbiting the Milky Way, only NASA’s Hubble Space Telescope can see who’s winning. The players are the Large and Small Magellanic Clouds, and as they gravitationally tug at each other, one of them has pulled out a huge amount of gas from its companion. This shredded and fragmented gas, called the Leading Arm, is being devoured by the Milky Way and feeding new star birth in our galaxy. But which dwarf galaxy is doing the pulling, and whose gas is now being feasted upon? Scientists used Hubble’s ultraviolet vision to chemically analyze the gas in the Leading Arm and determine its origin. After years of debate, we now have the answer to this “whodunit” mystery.

http://hubblesite.org/news_release/news/2018-15

Title: Re: Astronomy Thread
Post by: Star One on 03/26/2018 07:32 pm
Kepler Solves Mystery of Fast and Furious Explosions

Space Observatory Captures the Details of an Unusual Stellar Detonation

The universe is so huge that it's estimated that a star explodes as a supernova once every second. Astronomers capture a small fraction of these detonations because they are comparatively short-lived, like fireflies flickering on a summer evening. After skyrocketing to a sudden peak in brightness, a supernova can take weeks to slowly fade away.

For the past decade astronomers have been befuddled by a more curious "flash-in-the-pan" that pops up and then disappears in just a few days, not weeks. It's called a Fast-Evolving Luminous Transient (FELT). Only a few FELTs have been seen in telescopic sky surveys because they are so brief.

Then along came NASA's Kepler Space Telescope that caught a FELT in the act. Kepler's outstanding ability to precisely record changes in the brightness of celestial objects was designed to look for planets across our galaxy. But a great spinoff from the observatory is to go supernova hunting too.

Kelper's unique capabilities captured the properties of the blast. This allowed astronomers to exclude a range of theories about how FELTs happen, and converge on a plausible model. They conclude that the brief flash is from a vast shell of material around a supernova that abruptly lights up when the supernova blast wave crashes into it.

Release ID: STScI-2018-18

http://hubblesite.org/news_release/news/2018-18
Title: Re: Astronomy Thread
Post by: Star One on 03/28/2018 07:24 am
U2 Spy Plane Flies Through a Dazzling Aurora

https://video.nationalgeographic.com/video/news/180327-air-force-pilot-flies-into-aurora-vin-spd (https://video.nationalgeographic.com/video/news/180327-air-force-pilot-flies-into-aurora-vin-spd)
Title: Re: Astronomy Thread
Post by: Star One on 03/28/2018 08:06 pm
Life beyond Earth: No plate tectonics, no problem

Scientists prepare to look in unexpected places for ‘exoplanet biosignatures’

HOUSTON — (March 28, 2018) — Scientists looking for life on distant planets are making plans to search non-Earth-like planets based on discoveries within our solar system that are challenging long-standing ideas about habitable zones, plate tectonics and more.

In a new paper published online this week, Rice University geophysicist Adrian Lenardic and more than a dozen co-authors outline a path for both finding potential life signs around other stars and determining how likely it is that those signs are caused by alien life. The paper, “Exoplanet Biosignatures: Future Directions,” is available online and due to be published in Astrobiology.

An artist's impression of Ross 128 b, a temperate, rocky planet about 11 light-years from EarthLong Description
An artist’s impression of Ross 128 b, a temperate, rocky planet about 11 light-years from Earth that could have the necessary conditions for maintaining liquid surface water. (Photo courtesy of European Southern Observatory/M. Kornmesser)
Lenardic, who specializes in studying planetary dynamics, also authored an associated paper, “Volcanic-Tectonic Modes and Planetary Life Potential,” that will be published as a chapter in the upcoming “Handbook of Exoplanets” from Springer Publishing.

“It used to be the thought that life could only exist in a narrow zone near a planet’s star because you need to be there to maintain liquid water,” said Lenardic, professor of Earth, environmental and planetary sciences. “Then, we send Voyager out to a moon of Jupiter and, lo and behold, it shows strong indications of a subsurface ocean. That’s because there is another energy source that did not get its proper due — tidal forces from the intense gravitational pull of Jupiter.

“This has opened up the range over our own solar system in which life can exist, and I think a lot of the gist of the forthcoming papers is that much of what we’re seeing is expanding the zone and expanding our thinking about the conditions needed for life. So, as we look for life around other stars, we should also expand our search strategies or we might miss something.”

Astronomers have cataloged more than 3,700 planets around distant stars. The 21-foot diameter mirror on the James Webb Space Telescope, which is set to launch in 2019, will be able to examine the atmospheres of rocky planets around distant stars, and astronomers are already designing future missions and instruments that will look for specific atmospheric signatures of life.

“A goal was to frame the problem,” Lenardic said of the new biosignature paper, which sprang from an exoplanet workshop that brought together a range of scientists. “The workshop team wanted to come up with a means of assigning a likelihood of life based on a given set of observations of a distant planet.”

Adrian LenardicLong Description
Adrian Lenardic (Photo by Jeff Fitlow/Rice University)
He said the search for exolife is a team sport that involves biologists, astronomers, planetary scientists and others who collaborate through groups such as NASA’s Nexus for Exoplanet System Science (NExSS) project and the European Space Agency’s International Summer School in Astrobiology.

Lenardic’s contribution is to examine how the internal energy of planets, and associated volcanic-tectonic activity, influence their climate and ability to sustain life.

“When I teach planetary science, one question I actually give students is, ‘What is life? Give me a definition.’ And it’s not easy,” Lenardic said. He noted that students and working scientists have put forward a range of answers.

“But if we can agree on one thing, it’s that life needs energy,” he said. “We’ve thought about the sun as an energy source for a long time, and we’ve come to appreciate a planet’s internal energy, which comes from decay of radioactive elements within its rocky interior. Jupiter’s moons have taught us to also appreciate tidal forcing, and we’re starting to find exoplanets that have orbits that allow for significant tidal forcing.”

Lenardic said plate tectonics, much like the narrow habitable zone, is another long-held criterion for planetary habitability that is being challenged by recent findings.

Plate tectonics is the large-scale process that governs the movements of Earth’s crust.

“It is a particular surface manifestation of a planet’s internal energy, but it is not the only possible mode of volcanic and tectonic activity on a planet,” Lenardic said.

On Earth, plate tectonics plays a role in modulating climate, but the idea that plate tectonics is crucial for life is challenged by increasingly sophisticated models of planetary climates. For example, in a January study in the Journal of Geophysical Research, Lenardic and colleagues showed how water could be maintained on worlds without plate tectonics. The chapter in the upcoming “Handbook of Exoplanets” further explores this idea by considering planetary life potential under a range of tectonic modes that differ from Earth’s.

“I’m an optimist,” Lenardic said. “We’re at the first point in our history as humans where we might actually have some observations from other planets that we can use to test any of these ideas about life beyond our own. It can be easy to be Earth-centric and assume that life requires a planet like our own. But what we are seeing within our solar system is causing us to question this. One of the things I have learned from the history of exploring our own solar system is to be prepared for surprise. As we move beyond our solar system, in our search for life, that lesson is driving us to adapt our search strategies.”

Co-authors of the Astrobiology paper include lead author Sara Walker, Evgenya Shkolnik and Harrison Smith of Arizona State University; William Bains of the MIT; Leroy Cronin of the University of Glasgow; Shiladitya DasSarma of the University of Maryland School of Medicine; Sebastian Danielache of the Tokyo Institute of Technology and Sophia University in Tokyo; Shawn Domagal-Goldman of NASA’s Goddard Space Flight Center and the University of Washington’s Virtual Planetary Laboratory; Betul Kacar of Harvard, the University of Montana and the University of Arizona; Nancy Kiang of NASA’s Goddard Institute for Space Studies; Christopher Reinhard of the University of California, Riverside and Georgia Tech; William Moore of Hampton University and the National Institute of Aerospace in Hampton, Va.; and Edward Schwieterman of the Blue Marble Space Institute of Science in Seattle, the University of Washington’s Virtual Planetary Laboratory, the University of California, Riverside and the Universities Space Research Association in Columbia, Md.

-30-

High-resolution IMAGES are available for download at:

https://www.eso.org/public/usa/images/eso1736a/
CAPTION: An artist’s impression of Ross 128 b, a temperate, rocky planet about 11 light-years from Earth that could have the necessary conditions for maintaining liquid surface water. (Photo courtesy of European Southern Observatory/M. Kornmesser)

http://news.rice.edu/files/2018/03/0323_EXOLIFE-al-lg2-1ax3yr7.jpg
CAPTION: Adrian Lenardic (Photo by Jeff Fitlow/Rice University)

The Astrobiology paper is available at: https://arxiv.org/ftp/arxiv/papers/1705/1705.08071.pdf

The planetary dynamics paper is available at: https://www.researchgate.net/publication/320456190_Volcanic-Tectonic_Modes_and_Planetary_Life_Potential

Title: Re: Astronomy Thread
Post by: Star One on 03/28/2018 08:27 pm
Newly-discovered planet is hot, metallic and dense as Mercury

Hot, metallic, Earth-sized planet with a density similar to Mercury detected 339 light years away and characterised by global team of astronomers, including the University of Warwick
K2-229b is 20% larger than Earth but has a mass 2.6 times greater - and a dayside temperature of over 2000°C
Discovering details about far-flung planets across the universe gives us more clues as to how planets in our own solar system formed

https://warwick.ac.uk/newsandevents/pressreleases/newly-discovered_planet_is
Title: Re: Astronomy Thread
Post by: missinglink on 03/28/2018 09:21 pm
Newly-discovered planet is hot, metallic and dense as Mercury
There be gold in them thar planets, GOLD! and it's mine, all mine! you can't have any of it.
Title: Re: Astronomy Thread
Post by: Star One on 03/29/2018 06:36 am
Dark matter 'missing' in a galaxy far, far away

Quote
Galaxies and dark matter go hand in hand; you typically don't find one without the other. So when researchers uncovered a galaxy, known as NGC1052-DF2, that is almost completely devoid of the stuff, they were shocked.

https://m.phys.org/news/2018-03-dark-galaxy.html
Title: Re: Astronomy Thread
Post by: Star One on 03/29/2018 11:48 am
RARE 'RUNAWAY' SUPERGIANT STAR DISCOVERED SPEEDING ACROSS NEIGHBORING GALAXY AT 300,000 MPH

http://www.newsweek.com/rare-runaway-supergiant-star-discovered-speeding-across-neighboring-galaxy-864578
Title: Re: Astronomy Thread
Post by: leovinus on 03/29/2018 01:07 pm
Dark matter 'missing' in a galaxy far, far away

Quote
Galaxies and dark matter go hand in hand; you typically don't find one without the other. So when researchers uncovered a galaxy, known as NGC1052-DF2, that is almost completely devoid of the stuff, they were shocked.

https://m.phys.org/news/2018-03-dark-galaxy.html

A bit of context makes this even more interesting. Two years ago, the same author with the same instrument found a galaxy which was conjectured to consist of 99.9% dark matter https://www.space.com/33850-weird-galaxy-is-mostly-dark-matter.html (https://www.space.com/33850-weird-galaxy-is-mostly-dark-matter.html). In other words, we find galaxies with extreme mixing ratios <0..99.9> for matter and dark matter, and it seems more than just one example.
Title: Re: Astronomy Thread
Post by: Star One on 04/03/2018 07:49 pm
Astronomers find 72 bright and fast explosions

Quote
Gone in a (cosmological) flash: a team of astronomers found 72 very bright, but quick events in a recent survey and are still struggling to explain their origin. Miika Pursiainen of the University of Southampton will present the new results on Tuesday 3 April at the European Week of Astronomy and Space Science.

The scientists found the transients in data from the Dark Energy Survey Supernova Programme (DES-SN). This is part of a global effort to understand dark energy, a component driving an acceleration in the expansion of the Universe. DES-SN uses a large camera on a 4-metre telescope in the Cerro Tololo Inter-American Observatory (CTIO) in the Chilean Andes. The survey looks for supernovae, the explosion of massive stars at the end of their lives. A supernova explosion can briefly be as bright as a whole galaxy, made up of hundreds of billions of stars.

https://www.eurekalert.org/pub_releases/2018-04/ras-af7032918.php

Is the Milky Way getting bigger?

Quote
The galaxy we inhabit, the Milky Way, may be getting even bigger, according to Cristina Martínez-Lombilla, a PhD candidate at the Instituto de Astrofísica de Canarias in Tenerife, Spain, and her collaborators. She will present the work of her team in a talk on Tuesday 3 April at the European Week of Astronomy and Space Science in Liverpool.

https://www.eurekalert.org/pub_releases/2018-04/ras-itm032918.php

Gravitational waves created by black holes in the cenetr of most galaxies

Quote
Gravitational waves may be forged in the heart of the galaxy, says a new study led by PhD student Joseph Fernandez at Liverpool John Moores University. He sets out the work in a presentation on 3rd April at the European Week of Astronomy and Space Science in Liverpool.

https://www.sciencedaily.com/releases/2018/04/180402192817.htm

Title: Astronomy Thread
Post by: Star One on 04/04/2018 08:31 pm
Rare metals on Mars and Earth implicate colossal impacts

Quote
New research has revealed that a giant impact on Mars more than four billion years ago would explain the unusual amount of “iron loving” elements in the Red Planet.

https://astronomynow.com/2018/04/04/rare-metals-on-mars-and-earth-implicate-colossal-impacts/

Deep inside Perseus A – A telescope larger than the Earth makes a sharp image of the formation of black hole jets in the core of a radio galaxy

Quote
Researchers have imaged newly forming jets of plasma from a massive black hole with unprecedented accuracy. Radio images made with a combination of telescopes in space and on the ground resolve the jet structure merely a couple of hundred black hole radii or 12 light days from its launching site.

https://www.sciencedaily.com/releases/2018/04/180403090046.htm

New findings from NYU Abu Dhabi and JPL about how 'giant' planets impact neighbors' habitability

Quote
Abu Dhabi, UAE (April 4, 2018) - In a new study published today in the Astrophysical Journal, researchers from New York University Abu Dhabi and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, CA, share new findings about how the presence of "giant" planets (between 10 and 1000 times as large as the Earth) affects potentially habitable neighbors that would be discovered with the next generation of ground-based and space-borne telescopes.

https://www.eurekalert.org/pub_releases/2018-04/rai-nff040318.php

Artificial intelligence helps to predict likelihood of life on other worlds

Quote
Developments in artificial intelligence may help us to predict the probability of life on other planets, according to new work by a team based at Plymouth University. The study uses artificial neural networks (ANNs) to classify planets into five types, estimating a probability of life in each case, which could be used in future interstellar exploration missions. The work is presented at the European Week of Astronomy and Space Science (EWASS) in Liverpool on 4 April by Mr Christopher Bishop.

https://www.eurekalert.org/pub_releases/2018-04/ras-aih040318.php
Title: Re: Astronomy Thread
Post by: eeergo on 04/05/2018 01:57 pm
Extraordinary compendium of 8 protoplanetary disks imaged by ESO's SPHERE in the TTauri region:


https://arxiv.org/pdf/1803.10882.pdf
Title: Astronomy Thread
Post by: Star One on 04/05/2018 08:42 pm
Quote
A Columbia University-led team of astrophysicists has discovered a dozen black holes gathered around Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way Galaxy. The finding is the first to support a decades-old prediction, opening up myriad opportunities to better understand the universe.

"Everything you'd ever want to learn about the way big black holes interact with little black holes, you can learn by studying this distribution," said Columbia Astrophysicist Chuck Hailey, co-director of the Columbia Astrophysics Lab and lead author on the study. "The Milky Way is really the only galaxy we have where we can study how supermassive black holes interact with little ones because we simply can't see their interactions in other galaxies. In a sense, this is the only laboratory we have to study this phenomenon."

http://chandra.harvard.edu/press/18_releases/press_040418.html

eso1810 — Photo Release

Dead Star Circled by Light

Quote
MUSE data points to isolated neutron star beyond our galaxy

5 April 2018

Quote
New images from ESO’s Very Large Telescope in Chile and other telescopes reveal a rich landscape of stars and glowing clouds of gas in one of our closest neighbouring galaxies, the Small Magellanic Cloud. The pictures have allowed astronomers to identify an elusive stellar corpse buried among filaments of gas left behind by a 2000-year-old supernova explosion. The MUSE instrument was used to establish where this elusive object is hiding, and existing Chandra X-ray Observatory data confirmed its identity as an isolated neutron star.

http://www.eso.org/public/news/eso1810/

MIPT physicists design a model of Martian winter

Quote
A team of researchers from MIPT and their German and Japanese colleagues have designed a numerical model of the annual water cycle in the Martian atmosphere. Previously, the scientists focused their research on relatively large airborne dust particles that serve as water condensation nuclei on Mars. In this study, the MIPT team expanded the analysis to include smaller particles that are more elusive. As a result, the calculations turned out to be more accurate and consistent with the data obtained from Mars orbiters. The paper was published in the Journal of Geophysical Research: Planets.

https://www.eurekalert.org/pub_releases/2018-04/miop-mpd040518.php
Title: Astronomy Thread
Post by: Star One on 04/06/2018 07:52 pm
Hunting for dark matter in the smallest galaxies in the universe

Quote
Astrophysicists from the University of Surrey and the University of Edinburgh have created a new method to measure the amount of dark matter at the centre of tiny "dwarf" galaxies.

https://www.eurekalert.org/pub_releases/2018-04/uos-hf040618.php

Giant solar tornadoes put researchers in a spin

Quote
Despite their appearance solar tornadoes are not rotating after all, according to a team of scientists. A new analysis of these gigantic structures, each one several times the size of the Earth, indicates that they may have been misnamed because scientists have so far only been able to observe them using 2-dimensional images.

https://www.sciencedaily.com/releases/2018/04/180405223410.htm
Title: Re: Astronomy Thread
Post by: jebbo on 04/09/2018 07:08 am
The First Naked-Eye Superflare Detected from Proxima Centauri


Quote
Proxima b is a terrestrial-mass planet in the habitable-zone of Proxima Centauri. Proxima Centauri's high stellar activity however casts doubt on the habitability of Proxima b: sufficiently bright and frequent flares and any associated proton events may destroy the planet's ozone layer, allowing lethal levels of UV flux to reach its surface. In March 2016, the Evryscope observed the first naked-eye-visible superflare detected from Proxima Centauri. Proxima increased in brightness by a factor of ~68 during the superflare and released a bolometric energy of 10^33.5 erg, ~10X larger than any previously-detected flare from Proxima. Over the last two years the Evryscope has recorded 23 other large Proxima flares ranging in bolometric energy from 10^30.6 erg to 10^32.4 erg; coupling those rates with the single superflare detection, we predict at least five superflares occur each year. Simultaneous high-resolution HARPS spectroscopy during the Evryscope superflare constrains the superflare's UV spectrum and any associated coronal mass ejections. We use these results and the Evryscope flare rates to model the photochemical effects of NOx atmospheric species generated by particle events from this extreme stellar activity, and show that the repeated flaring is sufficient to reduce the ozone of an Earth-like atmosphere by 90% within five years. We estimate complete depletion occurs within several hundred kyr. The UV light produced by the Evryscope superflare therefore reached the surface with ~100X the intensity required to kill simple UV-hardy microorganisms, suggesting that life would struggle to survive in the areas of Proxima b exposed to these flares

https://arxiv.org/abs/1804.02001 (https://arxiv.org/abs/1804.02001)

Wow!
Title: Astronomy Thread
Post by: Star One on 04/09/2018 04:26 pm
South Africa’s MeerKAT radio telescope observes a rare burst of activity from an exotic star, demonstrating outstanding capabilities as a new instrument for scientific exploration

Quote
6 April 2018
An article published today in The Astrophysical Journal presents the study of a magnetar – a star that is one of the most magnetic objects known in the universe – that awoke in 2017 from a 3-year slumber. Radio observations that could only be made with MeerKAT, a telescope being built in the Northern Cape province of South Africa, triggered observations with NASA X-ray telescopes orbiting the Earth. This first publication in the scientific literature of astronomical discoveries requiring the use of MeerKAT heralds its arrival into the stable of world-class research instruments.

http://www.ska.ac.za/media-releases/south-africas-meerkat-radio-telescope-observes-a-rare-burst/

Cosmic magnetic fields with astonishing order

Quote
Modern radio telescopes unearth structures that nobody has ever expected.

http://news.rub.de/english/press-releases/2018-04-05-astronomy-cosmic-magnetic-fields-astonishing-order
Title: Re: Astronomy Thread
Post by: leovinus on 04/10/2018 08:26 pm
Dark matter 'missing' in a galaxy far, far away

Quote
Galaxies and dark matter go hand in hand; you typically don't find one without the other. So when researchers uncovered a galaxy, known as NGC1052-DF2, that is almost completely devoid of the stuff, they were shocked.

https://m.phys.org/news/2018-03-dark-galaxy.html

A bit of context makes this even more interesting. Two years ago, the same author with the same instrument found a galaxy which was conjectured to consist of 99.9% dark matter https://www.space.com/33850-weird-galaxy-is-mostly-dark-matter.html (https://www.space.com/33850-weird-galaxy-is-mostly-dark-matter.html). In other words, we find galaxies with extreme mixing ratios <0..99.9> for matter and dark matter, and it seems more than just one example.

Interesting discussion of this discovery at http://backreaction.blogspot.com/2018/04/no-that-galaxy-without-dark-matter-has.html (http://backreaction.blogspot.com/2018/04/no-that-galaxy-without-dark-matter-has.html).
Title: Re: Astronomy Thread
Post by: Star One on 04/10/2018 08:35 pm

Massive Stars as Major Factories of Galactic Cosmic Rays

Felix Aharonian, Ruizhi Yang, Emma de Oña Wilhelmi
(Submitted on 6 Apr 2018)
We report a remarkable constancy of the energy and radial distribution of the CR density, w(E,r)∝E−2.3r−1, derived around the prominent galactic clusters Westerlund 1, Westerlund 2, Cyg OB2, and, presumably, also towards three ultracompact clusters located in the Galactic Centre (GC). The 1/r decrement of the CR density with the distance from the star cluster is a distinct signature of continuous injection of CRs and their diffusion through ISM. The analysis of γ-ray data show that the hard energy spectra of parent protons continue up to ∼ 1 PeV, and the efficiency of conversion of kinetic energy of powerful stellar winds can be as high as 10 percent. This implies that the population of young massive stars can provide production of CRs at a rate of up to 1041 erg/s, which is sufficient to support the flux of Galactic CRs without invoking other source populations.

https://arxiv.org/abs/1804.02331
Title: Re: Astronomy Thread
Post by: Star One on 04/10/2018 08:42 pm
Dense stellar clusters may foster black hole megamergers

Quote
Black holes in these environments could combine repeatedly to form objects bigger than anything a single star could produce.

http://news.mit.edu/2018/dense-stellar-clusters-may-foster-black-hole-megamergers-0410
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 04/11/2018 06:23 pm
Four new 'hot Jupiter' exoplanets discovered (https://phys.org/news/2018-04-hot-jupiter-exoplanets.html) (Phys.org article)

HATS-39b, HATS-40b, HATS-41b, and HATS-42b: Three Inflated Hot Jupiters and a Super-Jupiter Transiting F Stars (https://arxiv.org/abs/1804.01623) (arXiv paper)

Quote
(Abstract)
We report the discovery of four transiting hot Jupiters from the HATSouth survey: HATS-39b, HATS-40b, HATS41b and HATS-42b. These discoveries add to the growing number of transiting planets orbiting moderately bright (12.5 < V < 13.7) F dwarf stars on short (2-5 day) periods. The planets have similar radii, ranging from 1.33(+0.29/-0.20) R_J for HATS-41b to 1.58(+0.16/-0.12) R_J for HATS-40b. Their masses and bulk densities, however, span more than an order of magnitude. HATS-39b has a mass of 0.63 +/- 0.13 M_J, and an inflated radius of 1.57 +/- 0.12 R_J, making it a good target for future transmission spectroscopic studies. HATS-41b is a very massive 9.7 +/- 1.6 M_J planet and one of only a few hot Jupiters found to date with a mass over 5 M_J. This planet orbits the highest metallicity star ([Fe/H] = 0.470 +/- 0.010) known to host a transiting planet and is also likely on an eccentric orbit. The high mass, coupled with a relatively young age (1.34 +0.31/-0.51 Gyr) for the host star, are factors that may explain why this planet's orbit has not yet circularised.
Title: Re: Astronomy Thread
Post by: Dao Angkan on 04/11/2018 07:06 pm
https://arxiv.org/abs/1804.03476

Gl15A c, a "Super Neptune" with a period around 7600 days, along with confirmation of the 11.44 day period "Super Earth" Gl15A b. That makes it the closest known multi-planet system to Earth at ~11.7ly (This binary system is more commonly known as Groombridge 34).
Title: Astronomy Thread
Post by: Star One on 04/11/2018 07:32 pm
Disk Imagery from Nearby Young Stars

Quote
Here’s an interesting situation: Around a star designated GSC 07396-00759, a member of a multiple star system, astronomers have found an edge-on disk. Such disks are helpful ways of studying planetary evolution, as we’re looking at gas, dust and planetesimals that represent a planetary system in the process of formation. But at GSC 07396-00759, the disk is more evolved than the gas-rich disk around the T Tauri star in the same system. In other words, we have two stars evidently of the same age whose disks show a different evolutionary pace.

https://www.centauri-dreams.org/2018/04/11/disk-imagery-from-nearby-young-stars/

After 30 years of R&D, breakthrough announced in dark matter detection technology, definitive search to begin for axion particles

Quote
This week, the Axion Dark Matter Experiment (ADMX) unveiled a new result, published in the journal Physical Review Letters, that places it in a category of one: it is the world’s first and only experiment to have achieved the necessary sensitivity to “hear” the telltale signs of dark matter axions. This technological breakthrough is the result of more than 30 years of research and development, with the latest piece of the puzzle coming in the form of a quantum-enabled device that allows ADMX to listen for axions more closely than any experiment ever built.

http://www.washington.edu/news/2018/04/09/admx-detection-technology/

Saturn's formation and early evolution at the origin of Jupiter's massive moons

Quote
The four massive Galilean satellites are believed to have formed within a circumplanetary disk during the last stages of Jupiter's formation. While the existence of a circum-jovian disk is supported by hydrodynamic simulations, no consensus exists regarding the origin and delivery mechanisms of the building blocks of the forming satellites. The opening of a gap in the circumsolar disk would have efficiently isolated Jupiter from the main sources of solid material. However, a reservoir of planetesimals should have existed at the outer edge of Jupiter's gap, where solids were trapped and accumulated over time. Here we show that the formation of Saturn's core within this reservoir, or its prompt inward migration, allows planetesimals to be redistributed from this reservoir towards Jupiter and the inner Solar System, thereby providing enough material to form the Galilean satellites and to populate the Main Belt with primitive asteroids. We find that the orbit of planetesimals captured within the circumjovian disk are circularized through friction with gas in a compact system comparable to the current radial extent of the Galilean satellites. The decisive role of Saturn in the delivery mechanism has strong implications for the occurrence of massive moons around extrasolar giant planets as they would preferentially form around planets within multiple planet systems.

https://arxiv.org/abs/1804.02892

The H.E.S.S. Galactic plane survey

Quote
We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) gamma-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE gamma-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of data, covering the Galactic plane at longitudes from l = 250 deg to 65 deg and latitudes |b| < 3 deg. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08 deg), sensitivity (1.5% Crab flux for point-like sources), and energy range (0.2-100 TeV). We constructed a source catalog with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this method, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible associations with cataloged objects, notably PWNe and energetic pulsars that could power VHE PWNe.

https://arxiv.org/abs/1804.02432

Weave: a semicoherent search implementation for continuous gravitational waves

Quote
All-sky surveys for isolated continuous gravitational waves present a significant data-analysis challenge. Semicoherent search methods are commonly used to efficiently perform the computationally-intensive task of searching for these weak signals in the noisy data of gravitational-wave detectors such as LIGO and Virgo. We present a new implementation of a semicoherent search method, Weave, that for the first time makes full use of a parameter-space metric to generate search templates in the correct resolution, combined with optimal lattices to minimize the required number of templates and hence the computational cost of the search. We describe the implementation of Weave and associated design choices, and characterize its behavior using semi-analytic models.

https://arxiv.org/abs/1804.03392
Title: Astronomy Thread
Post by: Star One on 04/11/2018 08:27 pm
Tour of the Moon in 4K

https://www.youtube.com/watch?v=nr5Pj6GQL2o (https://www.youtube.com/watch?v=nr5Pj6GQL2o)

Our Sun: Three Different Wavelengths

From March 20-23, 2018, NASA's Solar Dynamics Observatory captured three sequences of our Sun in three different extreme ultraviolet wavelengths. The resulting images illustrate how different features that appear in one sequence are difficult, if not impossible, to see in the others.

In the red sequence (304 Angstroms), we can see very small spicules - jets of solar material - and some small prominences at the Sun's edge, which are not easy to see in the other two sequences. In the second sequence (193 Angstroms), we can readily observe the large and dark coronal hole, though it is difficult to make out in the others. In the third (171 wavelengths), we can see strands of plasma waving above the surface, especially above the one small, but bright, active region near the right edge. These are just three of the ten extreme ultraviolet wavelengths in which SDO images the Sun every 12 seconds, every day.

https://www.nasa.gov/image-feature/our-sun-three-different-wavelengths
Title: Re: Astronomy Thread
Post by: Star One on 04/12/2018 08:16 pm
Captured! Radio telescope records a rare 'glitch' in a pulsar's regular pulsing beat

Quote
Pulsars are rapidly rotating neutron stars and sometimes they abruptly increase their rotation rate. This sudden change of spin rate is called a “glitch” and I was part of a team that recorded one happening in the Vela Pulsar, with the results published today in Nature.

Approximately 5-6% of pulsars are known to glitch. The Vela pulsar is perhaps the most famous – a very southern object that spins about 11.2 times per second and was discovered by scientists in Australia in 1968.

It is 1,000 light-years away, its supernova occurred about 11,000 years ago and roughly once every three years this pulsar suddenly speeds up in rotation.

These glitches are unpredictable, and one has never been observed with a radio telescope large enough to see individual pulses.

To understand what the glitch may be, first we need to understand what makes a pulsar.

https://theconversation.com/amp/captured-radio-telescope-records-a-rare-glitch-in-a-pulsars-regular-pulsing-beat-94815?__twitter_impression=true
Title: Re: Astronomy Thread
Post by: redliox on 04/15/2018 03:27 pm
Another astronomy news item:

TESS is due to launch in less than 24 hours; approximately 6:50 EST.
Title: Re: Astronomy Thread
Post by: Star One on 04/17/2018 08:00 pm
Powerful new camera developed to directly image exoplanets

Quote
University of California-Santa Barbara physicist Benjamin Mazin is leading an international team developing what they say is the world’s largest, most sophisticated superconducting camera in a bid to directly image exoplanets orbiting nearby stars.

While NASA is famed for the occasional convoluted acronym, the camera team came up with its own prize winner: DARKNESS, which stands for “DARK-speckle Near-infrared Energy-resolved Superconducting Spectrophotometer.”

“It is the first 10,000-pixel integral field spectrograph designed to overcome the limitations of traditional semiconductor detectors,” UC Santa Barbara said in a release. “It employs Microwave Kinetic Inductance Detectors that, in conjunction with a large telescope and an adaptive optics system, enable direct imaging of planets around nearby stars.”

The DARKNESS camera can take thousands of images per second without the “read noise” and other factors that affect more traditional cameras. It also can determine the wavelength and arrival time of every photon striking its detector.

“This technology will lower the contrast floor so that we can detect fainter planets,” Mazin said in the UC Santa Barbara release. “Mazin explained. “We hope to approach the photon noise limit … allowing us to see planets 100 million times fainter than the star. At those contrast levels, we can see some planets in reflected light, which opens up a whole new domain of planets to explore.

“The really exciting thing is that this is a technology pathfinder for the next generation of telescopes,” he said.

https://astronomynow.com/2018/04/16/powerful-new-camera-developed-to-image-exoplanets/
Title: Re: Astronomy Thread
Post by: Star One on 04/17/2018 08:28 pm
Spaceflight from Super-Earths is difficult

Quote
Many rocky exoplanets are heavier and larger than the Earth, and have higher surface gravity. This makes space-flight on these worlds very challenging, because the required fuel mass for a given payload is an exponential function of planetary surface gravity, ∼3.3exp(g0). We find that chemical rockets still allow for escape velocities on Super-Earths up to 10x Earth mass. More massive rocky worlds, if they exist, would require other means to leave the planet, such as nuclear propulsion.

https://arxiv.org/abs/1804.04727

A Search for Dark Matter Annihilation in the Milky Way Halo

Quote
The Milky Way halo is the brightest source of dark matter annihilation on the sky. Indeed, the potential strength of the Galactic dark matter signal can supersede that expected from dwarf galaxies and galaxy groups even in regions away from the Inner Galaxy. In this Letter, we present the results of a search for dark matter annihilation in the smooth Milky Way halo for |b|>20∘ and r<50∘ using 413 weeks of Fermi Pass 8 data within the energy range of ∼0.8-50 GeV. We exclude thermal dark matter with mass below ∼70 GeV that annihilates to bb¯ at the 95% confidence level, providing the strongest limits on the annihilation cross section in this mass range. We explore how these limits depend on uncertainties in cosmic-ray foregrounds by varying over a set of reasonable models. These results exclude the region of dark matter parameter space that is consistent with the excess of ∼GeV photons observed at the Galactic Center for the bb¯ annihilation channel and, for the first time, put the τ+τ− explanation under tension.

https://arxiv.org/abs/1804.04132

Earth as an Exoplanet

Quote
The search for habitable and inhabited environments beyond our planet commonly focuses on analogs to Earth, especially in the case of exoplanets. Observations from ground-based facilities, satellites, and spacecraft have yielded a rich collection of data that can be used to effectively view a distant Earth within the context of exoplanet characterization. Application of planetary and exoplanetary remote sensing techniques to these datasets then enables the development of approaches to detecting signatures of habitability and life on other worlds. In addition, an array of models have also been used to simulate exoplanet-like datasets for the distant Earth, thereby providing insights that are often complementary to those from existing observations. Of course, Earth's atmosphere and surface environment has evolved substantially in the 4.5 billion years since our planet formed. A combination of in situ geological and bio-geochemical modeling studies of our planet have provided glimpses of environments that, while technically bellonging to our Earth, are seemingly alien worlds. Understanding the myriad ways Earth has been habitable and inhabited, coupled with remote sensing approaches honed on the distant Earth, provides a key guide to recognizing potentially life-bearing environments in distant planetary systems.

https://arxiv.org/abs/1804.04138

Shadows of rotating wormholes

Quote
We study shadows cast by a certain class of rotating wormholes and point out the crucial role of a rotating wormhole throat in the formation of a shadow, a crucial point overlooking of which has resulted erroneous results in the earlier studies on shadows of the same class of rotating wormholes. We explore the dependence of the shadows on the spin of the wormholes. We compare our results with that of the Kerr black hole. With increasing values of the spin, the shapes of the wormhole shadows start deviating considerably from that of the black hole. Such considerable deviation, if detected in future observations, may possibly indicate the presence of a wormhole. In other words, the results obtained here indicate that, through the observations of their shadows, the wormholes which are considered in this work and have reasonable spin, can be distinguished from a black hole.

https://arxiv.org/abs/1803.11422

Highly Volcanic Exoplanets, Lava Worlds, and Magma Ocean Worlds: An Emerging Class of Dynamic Exoplanets of Significant Scientific Priority

Quote
Highly volcanic exoplanets, which can be variously characterized as 'lava worlds', 'magma ocean worlds', or 'super-Ios' are high priority targets for investigation. The term 'lava world' may refer to any planet with extensive surface lava lakes, while the term 'magma ocean world' refers to planets with global or hemispherical magma oceans at their surface. 'Highly volcanic planets', including super-Ios, may simply have large, or large numbers of, active explosive or extrusive volcanoes of any form. They are plausibly highly diverse, with magmatic processes across a wide range of compositions, temperatures, activity rates, volcanic eruption styles, and background gravitational force magnitudes. Worlds in all these classes are likely to be the most characterizable rocky exoplanets in the near future due to observational advantages that stem from their preferential occurrence in short orbital periods and their bright day-side flux in the infrared. Transit techniques should enable a level of characterization of these worlds analogous to hot Jupiters. Understanding processes on highly volcanic worlds is critical to interpret imminent observations. The physical states of these worlds are likely to inform not just geodynamic processes, but also planet formation, and phenomena crucial to habitability. Volcanic and magmatic activity uniquely allows chemical investigation of otherwise spectroscopically inaccessible interior compositions. These worlds will be vital to assess the degree to which planetary interior element abundances compare to their stellar hosts, and may also offer pathways to study both the very young Earth, and the very early form of many silicate planets where magma oceans and surface lava lakes are expected to be more prevalent. We suggest that highly volcanic worlds may become second only to habitable worlds in terms of both scientific and public long-term interest.

https://arxiv.org/abs/1804.05110
Title: Re: Astronomy Thread
Post by: Star One on 04/18/2018 07:57 pm
Study: Diamond from the sky may have come from 'lost planet'

Quote
Fragments of a meteorite that fell to Earth about a decade ago provide compelling evidence of a lost planet that once roamed our solar system, according to a study published Tuesday.

https://phys.org/news/2018-04-diamond-sky-lost-planet.amp?
Title: Astronomy Thread
Post by: Star One on 04/19/2018 07:37 pm
The GALAH Survey: Second Data Release

Quote
The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of the Milky Way and designed to deliver chemical information complementary to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342,682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community. Here we present the target selection, observation, data reduction and detailed explanation of how the spectra were analysed to estimate stellar parameters and element abundances. For the stellar analysis, we have used a multi-step approach. We use the physics-driven spectrum synthesis of Spectroscopy Made Easy (SME) to derive stellar labels (Teff, logg, [Fe/H], [X/Fe], vmic, vsini, AKS) for a representative training set of stars. This information is then propagated to the whole survey with the data-driven method of The Cannon. Special care has been exercised in the spectral synthesis to only consider spectral lines that have reliable atomic input data and are little affected by blending lines. Departures from local thermodynamic equilibrium (LTE) are considered for several key elements, including Li, O, Na, Mg, Al, Si, and Fe, using 1D MARCS stellar atmosphere models. Validation tests including repeat observations, Gaia benchmark stars, open and globular clusters, and K2 asteroseismic targets lend confidence in our methods and results. Combining the GALAH DR2 catalogue with the kinematic information from Gaia will enable a wide range of Galactic Archaeology studies, with unprecedented detail, dimensionality, and scope.

https://arxiv.org/abs/1804.06041


Superflares on Giant Stars

Quote
The Kepler mission identified huge flares on various stars including some of solar type. These events are substantially more energetic than solar flares, and so they are referred to as superflares. Even a small probability of such a superflare on the Sun would be a menace to modern society. A flare comparable in energy with that of superflares was observed on 24th and 25th September on the binary HK Lac. Unlike the Kepler stars, there are observations of differential rotation for HK Lac. This differential rotation appears to be anti-solar. For anti-solar differential rotation, dynamo models can give magnetic activity waves of dipole symmetry as well as quasi-stationary magnetic configurations with quadrupole symmetry. The magnetic energy of such stationary configurations is usually about two orders of magnitude higher than that associated with activity waves. We believe that this mechanism could provide sufficient energy to produce superflares on late type stars, and present some simple models in support of this idea.

https://arxiv.org/abs/1804.06315
Title: Re: Astronomy Thread
Post by: Star One on 04/20/2018 08:10 pm

An Unexpected Dip in the Solar Gamma-Ray Spectrum

Quote
The solar disk is a bright source of multi-GeV gamma rays, due to the interactions of hadronic cosmic rays with the solar atmosphere. However, the underlying production mechanism is not understood, except that its efficiency must be greatly enhanced by magnetic fields that redirect some cosmic rays from ingoing to outgoing before they interact. To elucidate the nature of this emission, we perform a new analysis of solar atmospheric gamma rays with 9 years of Fermi-LAT data, which spans nearly the full 11-year solar cycle. We detect significant gamma-ray emission from the solar disk from 1 GeV up to ≳200 GeV. The overall gamma-ray spectrum is much harder (∼E−2.2γ) than the cosmic-ray spectrum (∼E−2.7CR). We find a clear anticorrelation between the solar cycle phase and the gamma-ray flux between 1-10 GeV. Surprisingly, we observe a spectral dip between ∼30-50 GeV in an otherwise power-law spectrum. This was not predicted, is not understood, and may provide crucial clues to the gamma-ray emission mechanism. The flux above 100 GeV, which is brightest during the solar minimum, poses exciting opportunities for HAWC, LHAASO, IceCube, and KM3NeT.

https://arxiv.org/abs/1804.06846
Title: Astronomy Thread
Post by: Star One on 04/20/2018 08:44 pm
I prefer this explanation for dark matter than some exotic particle. It wouldn’t surprise me if we don’t eventually find that Black Holes are a dominating factor in the universe.

Quote
CfA astronomer Qirong Zhu led a group of four scientists investigating the possibility that today's dark matter is composed of primordial black holes, following up on previously published suggestions. If galaxy halos are made of black holes, they should have a different density distribution than halos made of exotic particles. There are some other differences as well - black hole halos are expected to form earlier in a galaxy’s evolution than do some other kinds of halos. The scientists suggest that looking at the stars in the halos of faint dwarf galaxies can probe these effects because dwarf galaxies are small and faint (they shine with a mere few thousand solar luminosities) where slight effects can be more easily spotted. The team ran a set of computer simulations to test whether dwarf galaxy halos might reveal the presence of primordial black holes, and they find that they could: interactions between stars and primordial halo black holes should slightly alter the sizes of the stellar distributions. The astronomers also conclude that such black holes would need to have masses between about two and fourteen solar masses, right in the expected range for these exotic objects (although smaller than the black holes recently spotted by gravitational wave detectors) and comparable to the conclusions of other studies. The team emphasizes, however, that all the models are still inconclusive and the nature of dark matter remains elusive.

https://www.cfa.harvard.edu/news/su201816
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 04/24/2018 05:11 am
The Solar Neighborhood XLIV: RECONS Discoveries within 10 Parsecs (https://arxiv.org/abs/1804.07377) (arXiv)

Quote
(Abstract)
We describe the 44 systems discovered to be within 10 parsecs of the Sun by the RECONS team, primarily via the long-term astrometry program at CTIO that began in 1999. The systems --- including 41 with red dwarf primaries, 2 white dwarfs, and 1 brown dwarf --- have been found to have trigonometric parallaxes greater than 100 milliarcseconds (mas), with errors of 0.4--2.4 mas in all but one case. We provide updated astrometric, photometric (VRIJHK magnitudes), spectral type, and multiplicity information here. Among these are 14 systems that are new entries to the 10 parsec sample based on parallaxes measured at the CTIO/SMARTS 0.9m telescope. These are the first parallaxes for nine systems, while the remaining five systems had previously measured parallaxes with errors greater than 10 mas or values placing them beyond 10 parsecs. We also present parallaxes from URAT for seven of these systems, providing additional evidence that they are closer than 10 parsecs. In addition, we provide new data for 22 systems that were previously known to lie within 10 parsecs and 9 systems reported to be closer than that horizon but for which new parallaxes place them further away. In total, we provide data for 75 systems, for which 71 have new or updated parallaxes here.
The 44 systems added by RECONS comprise one of every seven systems known within 10 parsecs. We illustrate the evolution of the 10 parsec sample from the 191 systems known when the final Yale Parallax Catalog (YPC) was published in 1995 to the 316 systems known today. Even so close to the Sun, additional discoveries of red and brown dwarfs (and perhaps even white dwarfs) are likely, both as primaries and secondaries, although we estimate that at least 90% of the stellar systems closer than 10 parsecs have now been identified.

It's astonishing - to me anyway - that the number of known systems in our local stellar neighbourhood has increased by over 50% in just over twenty years, with more discoveries likely!
Title: Re: Astronomy Thread
Post by: Star One on 04/24/2018 08:49 pm
Scientists finally confirm that Uranus is surrounded by fart clouds

Quote
Still, scientists had never directly detected the presence of these stinky molecules. Until now, that is. The authors of the new study examined sunlight bouncing off Uranus as captured by the 8-meter Gemini North telescope in Hawaii. Scientists determined what sorts of molecules were inside the atmosphere by examining the light it reflected in infrared. Different compounds absorb and cast off different wavelengths of light—creating a distinct and identifiable signature if you know what to look for. Think of it as dusting for fingerprints, but instead of a suspect, you're looking for molecular compounds. The group says they were just barely able to detect the signatures they sought; it took a telescope as sensitive as Gemini and conditions as clear and perfect as those found at its home on Mauna Kea. Even though no one has ever smelt it, scientists can now say with certainty which molecules have dealt it.

https://www.popsci.com/uranus-hydrogen-sulfide-cloud
Title: Re: Astronomy Thread
Post by: eeergo on 04/25/2018 12:42 am
 :-[


This is the level now in scientific divulgation?

An article riddled with 5-year-old-worth jokes, glaring misspellings (Uranusians? really?), repetitions (how many times can you say fart in an article and not try to use synonyms?) and no actual science to convey, apart from the fun fact hydrogen sulphide smells bad. And it's actually just a dumbed-down version of the original release: https://www.gemini.edu/node/21050 - which isn't even directly linked to! Rachael Feltman either had a terrible workday or doesn't deserve the atrium she's writing for; motivated high-school bloggers regularly do better than that.

I'd say the takeaway message would be this one, neglected in the PopSci article:


Quote
According to Fletcher, when a cloud deck forms by condensation, it locks away the cloud-forming gas in a deep internal reservoir, hidden away beneath the levels that we can usually see with our telescopes. "Only a tiny amount remains above the clouds as a saturated vapour," said Fletcher. "And this is why it is so challenging to capture the signatures of ammonia and hydrogen sulfide above cloud decks of Uranus. The superior capabilities of Gemini finally gave us that lucky break," concludes Fletcher.

The detection of gaseous H2S at these pressure levels adds to the weight of evidence that the principal constituent of 1.2–3-bar cloud is likely to be H2S ice.
Title: Astronomy Thread
Post by: Star One on 04/25/2018 05:52 am



This is the level now in scientific divulgation?

An article riddled with 5-year-old-worth jokes, glaring misspellings (Uranusians? really?), repetitions (how many times can you say fart in an article and not try to use synonyms?) and no actual science to convey, apart from the fun fact hydrogen sulphide smells bad. And it's actually just a dumbed-down version of the original release: https://www.gemini.edu/node/21050 - which isn't even directly linked to! Rachael Feltman either had a terrible workday or doesn't deserve the atrium she's writing for; motivated high-school bloggers regularly do better than that.

I'd say the takeaway message would be this one, neglected in the PopSci article:


Quote
According to Fletcher, when a cloud deck forms by condensation, it locks away the cloud-forming gas in a deep internal reservoir, hidden away beneath the levels that we can usually see with our telescopes. "Only a tiny amount remains above the clouds as a saturated vapour," said Fletcher. "And this is why it is so challenging to capture the signatures of ammonia and hydrogen sulfide above cloud decks of Uranus. The superior capabilities of Gemini finally gave us that lucky break," concludes Fletcher.

The detection of gaseous H2S at these pressure levels adds to the weight of evidence that the principal constituent of 1.2–3-bar cloud is likely to be H2S ice.

Thanks for contributing to the belief some have about this forum of being overly poefaced and lacking in any humour what so ever.
Title: Re: Astronomy Thread
Post by: eeergo on 04/25/2018 07:14 am

You would find a fair number of the people who know me personally that consider I engage in inappropriate scatologic jokes, among other -for me- hilarious topics and behaviors, far too often for my background and age range ;)


I'm just disheartened to see how many people lately (I sound like an old (H2S) fart and I'm merely 30!), including some very highly qualified professionals when exploring topics other than their very narrow day job specialized focus, just stick with frivolous and inconsequential ideas, neglecting any kind of deeper insight. If all everything that gets clicks (=popularity=money in this mercantilized world) are articles of this kind, this worrying trend can only get worse, especially now viral trends are the norm and critical analysis is regressing.


Mind you, I would even enjoy this angle if it was intelligently exploited, for instance:
- what characteristics make H2S important in Uranus?
- where is it located?
- where could it come from and what uncertainties drive this determination?
- how does it behave?
- how exactly do we detect it in the spectra?
- and the burning pressing question everyone is aching to know the answer to - how come it's both in an icy giant's atmosphere and in our own little internal "atmosphere"? I honestly would love to know!


But seeing one of the most popular scientific divulgation magazines in the United States unashamedly and stylessly write on "farts" (several times), "Uranusians", ways a person would gruesomely die in Uranus' atmosphere, not reporting the actual discovery it claims to report, and lazily using the "origin-of-life" wildcard to handwave some sciency-sounding justification for the rampage without even linking to the horse's mouth, is just distasteful. If this is the new standard, I'm glad NSF "doesn't have sense of humor", wouldn't you agree?


Ok, now to make up for the [/rant]  :
Title: Re: Astronomy Thread
Post by: Star One on 04/25/2018 08:18 pm
Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass

Quote
Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]), but also the mass (M⋆). However, measuring accurate masses for subgiants and giants is far more challenging than it is for their main-sequence counterparts, which has led to recent concerns regarding the veracity of the correlation between stellar mass and planet occurrence. In order to address these concerns we use HIRES spectra to perform a spectroscopic analysis on an sample of 245 subgiants and derive new atmospheric and physical parameters. We also calculate the space velocities of this sample in a homogeneous manner for the first time. When reddening corrections are considered in the calculations of stellar masses and a -0.12 M⊙ offset is applied to the results, the masses of the subgiants are consistent with their space velocity distributions, contrary to claims in the literature. Similarly, our measurements of their rotational velocities provide additional confirmation that the masses of subgiants with M⋆≥1.6 M⊙ (the "Retired A Stars") have not been overestimated in previous analyses. Using these new results for our sample of evolved stars, together with an updated sample of FGKM dwarfs, we confirm that giant planet occurrence increases with both stellar mass and metallicity up to 2.0 M⊙. We show that the probability of formation of a giant planet is approximately a one-to-one function of the total amount of metals in the protoplanetary disk M⋆10[Fe/H]. This correlation provides additional support for the core accretion mechanism of planet formation.

https://arxiv.org/abs/1804.09082
Title: Astronomy Thread
Post by: Star One on 04/26/2018 07:59 pm
Researchers simulate conditions inside 'super-Earths'

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Simulations offer insight into what previously had been limited to extrapolations and theoretical calculations

https://hub.jhu.edu/2018/04/26/exoplanet-cores-super-earth/

Astronomers Witness Galaxy Megamerger

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ALMA has uncovered 14 distant galaxies that are poised to merge, forming the core of what will eventually become a colossal galaxy cluster.

https://public.nrao.edu/news/2018-alma-megamerger/
Title: Re: Astronomy Thread
Post by: Star One on 04/28/2018 07:23 pm
New estimates of Mercury's thin, dense crust

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After the probe's mission ended in 2015, planetary scientists estimated Mercury's crust was roughly 22 miles thick. One University of Arizona scientist disagrees.

Using the most recent mathematical formulas, Lunar and Planetary Laboratory associate staff scientist Michael Sori estimates that the Mercurial crust is just 16 miles thick and is denser than aluminum. His study, "A Thin, Dense Crust for Mercury," will be published May 1 in Earth and Planetary Science Letters and is currently available online.

https://www.eurekalert.org/pub_releases/2018-04/uoa-neo042618.php
Title: Re: Astronomy Thread
Post by: Star One on 04/30/2018 08:43 pm
Old Data, New Tricks: Fresh Results from NASA’s Galileo Spacecraft 20 Years On
Galileo image of Ganymede


Far across the solar system, from where Earth appears merely as a pale blue dot, NASA’s Galileo spacecraft spent eight years orbiting Jupiter. During that time, the hearty spacecraft — slightly larger than a full-grown giraffe — sent back spates of discoveries on the gas giant’s moons, including the observation of a magnetic environment around Ganymede that was distinct from Jupiter’s own magnetic field. The mission ended in 2003, but newly resurrected data from Galileo’s first flyby of Ganymede is yielding new insights about the moon’s environment — which is unlike any other in the solar system.

“We are now coming back over 20 years later to take a new look at some of the data that was never published and finish the story,” said Glyn Collinson, lead author of a recent paper about Ganymede's magnetosphere at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We found there’s a whole piece no one knew about.”

The new results showed a stormy scene: particles blasted off the moon’s icy surface as a result of incoming plasma rain, and strong flows of plasma pushed between Jupiter and Ganymede due to an explosive magnetic event occurring between the two bodies’ magnetic environments. Scientists think these observations could be key to unlocking the secrets of the moon, such as why Ganymede’s auroras are so bright.

In 1996, shortly after arriving at Jupiter, Galileo made a surprising discovery: Ganymede had its own magnetic field. While most planets in our solar system, including Earth, have magnetic environments — known as magnetospheres — no one expected a moon to have one.

Between 1996 and 2000, Galileo made six targeted flybys of Ganymede, with multiple instruments collecting data on the moon’s magnetosphere. These included the spacecraft's Plasma Subsystem, or PLS, which measured the density, temperature and direction of the plasma — excited, electrically charged gas — flowing through the environment around Galileo. New results, recently published in the journal Geophysical Research Letters, reveal interesting details about the magnetosphere's unique structure.

We know that Earth’s magnetosphere — in addition to helping make compasses work and causing auroras — is key to in sustaining life on our planet, because it helps protect our planet from radiation coming from space. Some scientists think Earth’s magnetosphere was also essential for the initial development of life, as this harmful radiation can erode our atmosphere. Studying magnetospheres throughout the solar system not only helps scientists learn about the physical processes affecting this magnetic environment around Earth, it helps us understand the atmospheres around other potentially habitable worlds, both in our own solar system and beyond.

Ganymede’s magnetosphere offers the chance to explore a unique magnetic environment located within the much larger magnetosphere of Jupiter. Nestled there, it’s protected from the solar wind, making its shape different from other magnetospheres in the solar system. Typically, magnetospheres are shaped by the pressure of supersonic solar wind particles flowing past them. But at Ganymede, the relatively slower-moving plasma around Jupiter sculpts the moon's magnetosphere into a long horn-like shape that stretches ahead of the moon in the direction of its orbit.

Flying past Ganymede, Galileo was continually pummeled by high-energy particles — a battering the moon is also familiar with. Plasma particles accelerated by the Jovian magnetosphere, continually rain down on Ganymede’s poles, where the magnetic field channels them toward the surface. The new analysis of Galileo PLS data showed plasma being blasted off the moon’s icy surface due to the incoming plasma rain.

“There are these particles flying out from the polar regions, and they can tell us something about Ganymede’s atmosphere, which is very thin,” said Bill Paterson, a co-author of the study at NASA Goddard, who served on the Galileo PLS team during the mission. “It can also tell us about how Ganymede’s auroras form.”

This visualization shows a simplified model of Jupiter’s magnetosphere, designed to illustrate the scale, and basic features of the structure and impacts of the magnetic axis (cyan arrow) offset from the planetary rotation axis (blue arrow). The semi-transparent gray mesh in the distance represents the boundary of the magnetosphere.

Ganymede has auroras, or northern and southern lights, just like Earth does. However, unlike our planet, the particles causing Ganymede’s auroras come from the plasma surrounding Jupiter, not the solar wind. When analyzing the data, the scientists noticed that during its first Ganymede flyby, Galileo fortuitously crossed right over Ganymede’s auroral regions, as evidenced by the ions it observed raining down onto the surface of the moon’s polar cap. By comparing the location where the falling ions were observed with data from Hubble, the scientists were able to pin down the precise location of the auroral zone, which will help them solve mysteries, such as what causes the auroras.

As it cruised around Jupiter, Galileo also happened to fly right through an explosive event caused by the tangling and snapping of magnetic field lines. This event, called magnetic reconnection, occurs in magnetospheres across our solar system. For the first time, Galileo observed strong flows of plasma pushed between Jupiter and Ganymede due to a magnetic reconnection event occurring between the two magnetospheres. It’s thought that this plasma pump is responsible for making Ganymede’s auroras unusually bright.

Future study of the PLS data from that encounter may yet provide new insights related to subsurface oceans previously determined to exist within the moon using data from both Galileo and the Hubble Space Telescope.

The research was funded by NASA’s Solar System Workings program and the Galileo mission managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, for the agency’s Science Mission Directorate in Washington.

https://www.nasa.gov/feature/goddard/2018/old-data-new-tricks-fresh-results-from-nasa-s-galileo-spacecraft-20-years-on
Title: Re: Astronomy Thread
Post by: Star One on 05/01/2018 05:16 pm
Optimal Target Stars in the Search for Life

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The selection of optimal targets in the search for life represents a highly important strategic issue. In this Letter, we evaluate the benefits of searching for life around a potentially habitable planet orbiting a star of arbitrary mass relative to a similar planet around a Sun-like star. If recent physical arguments implying that the habitability of planets orbiting low-mass stars is selectively suppressed are correct, we find that planets around solar-type stars may represent the optimal targets.

http://iopscience.iop.org/article/10.3847/2041-8213/aabd86/meta
Title: Re: Astronomy Thread
Post by: Star One on 05/02/2018 07:55 pm
Przybylski's star is an extremely slow rotator, study finds

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Now, a team of astronomers led by Swetlana Hubrig of the Leibniz Institute for Astrophysics Potsdam in Germany, presents a new research regarding Przybylski's star, which focuses on magnetic and pulsational variability of this object. The study, based on observations performed between June 2015 and June 2017 with the use of the High Accuracy Radial velocity Planet Searcher polarimeter (HARPSpol) at ESO's 3.6 m telescope in Chile, has also found that the star, besides its chemical peculiarity, is also unusual when it comes to its rotation.

"Our analysis of newly acquired and historic longitudinal magnetic field measurements indicates that Przybylski's star is also unusual with respect to its extremely slow rotation," the researchers wrote in the paper.

Hubrig's team found that the probable length of the rotation period of Przybylski's star is about 188 years. This calculation was made by analyzing all available longitudinal magnetic field measurements and adopting a dipolar structure of the magnetic field of the star.

https://phys.org/news/2018-05-przybylski-star-extremely-rotator.amp
Title: Re: Astronomy Thread
Post by: Star One on 05/07/2018 07:38 pm
What will happen when our sun dies?

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Scientists agree the sun will die in approximately 10 billion years, but they weren't sure what would happen next...until now.

A team of international astronomers, including Professor Albert Zijlstra from the University of Manchester, predict it will turn into a massive ring of luminous, interstellar gas and dust, known as a planetary nebula.

A planetary nebula marks the end of 90% of all stars active lives and traces the star's transition from a red giant to a degenerate white dwarf. But, for years, scientists weren't sure if the sun in our galaxy would follow the same fate: it was thought to have too low mass to create a visible planetary nebula.

To find out the team developed a new stellar, data-model that predicts the lifecycle of stars. The model was used to predict the brightness (or luminosity) of the ejected envelope, for stars of different masses and ages.

https://www.eurekalert.org/pub_releases/2018-05/uom-wwh050418.php
Title: Astronomy Thread
Post by: Star One on 05/09/2018 08:13 pm
Detecting Exomoons Via Doppler Monitoring of Directly Imaged Exoplanets

Recently, Teachey, Kipping, and Schmitt (2017) reported the detection of a candidate exomoon, tentatively designated Kepler-1625b I, around a giant planet in the Kepler field. The candidate exomoon would be about the size and mass of Neptune, considerably larger than any moon in our Solar System, and if confirmed, would be the first in a new class of giant moons or binary planets. Motivated by the large mass ratio in the Kepler-1625b planet and satellite system, we investigate the detectability of similarly massive exomoons around directly imaged exoplanets via Doppler spectroscopy. The candidate moon around Kepler-1625b would induce a radial velocity signal of about 200 m/s on its host planet, large enough that similar moons around directly imaged planets orbiting bright, nearby stars might be detected with current or next generation instrumentation. In addition to searching for exomoons, a radial velocity survey of directly imaged planets could reveal the orientations of the planets' spin axes, making it possible to identify Uranus analogs.

https://arxiv.org/abs/1805.01903
Title: Re: Astronomy Thread
Post by: Star One on 05/10/2018 05:51 pm
OU Study Explains Why Mars Growth Stunted

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NORMAN – A University of Oklahoma astrophysics team explains why the growth of Mars was stunted by an orbital instability among the outer solar system’s giant planets in a new study on the evolution of the young solar system. The OU study builds on the widely-accepted Nice Model, which invokes a planetary instability to explain many peculiar observed aspects of the outer solar system. An OU model used computer simulations to show how planet accretion (growth) is halted by the outer solar system instability. Without it, Mars possibly could have become a larger, habitable planet like Earth.

https://www.ou.edu/publicaffairs/archives/2018/may/OUStudyExplainsWhyMarsGrowthStunted
Title: Re: Astronomy Thread
Post by: Star One on 05/10/2018 07:31 pm
NASA’s NICER Mission Finds an X-ray Pulsar in a Record-fast Orbit

Scientists analyzing the first data from the Neutron star Interior Composition Explorer (NICER) mission have found two stars that revolve around each other every 38 minutes — about the time it takes to stream a TV drama. One of the stars in the system, called IGR J17062–6143 (J17062 for short), is a rapidly spinning, superdense star called a pulsar. The discovery bestows the stellar pair with the record for the shortest-known orbital period for a certain class of pulsar binary system.

The data from NICER also show J17062’s stars are only about 186,000 miles (300,000 kilometers) apart, less than the distance between Earth and the Moon. Based on the pair’s breakneck orbital period and separation, scientists involved in a new study of the system think the second star is a hydrogen-poor white dwarf.

“It’s not possible for a hydrogen-rich star, like our Sun, to be the pulsar’s companion,” said Tod Strohmayer an astrophysicist at Goddard and lead author on the paper. “You can’t fit a star like that into an orbit so small.”

https://youtu.be/B_JcarjiuDQ

The stars of IGR J17062–6143, illustrated here, circle each other every 38 minutes, the fastest-known orbit for a binary system containing an accreting millisecond X-ray pulsar. As they revolve, a superdense pulsar pulls gas from a lightweight white dwarf. The two stars are so close they would fit between Earth and the Moon.
Credits: NASA’s Goddard Space Flight Center
Download this video in HD formats from NASA Goddard's Scientific Visualization Studio
A previous 20-minute observation by the Rossi X-ray Timing Explorer (RXTE) in 2008 was only able to set a lower limit for J17062’s orbital period. NICER, which was installed aboard the International Space Station last June, has been able to observe the system for much longer periods of time. In August, the instrument focused on J17062 for more than seven hours over 5.3 days. Combining additional observations in October and November, the science team was able to confirm the record-setting orbital period for a binary system containing what astronomers call an accreting millisecond X-ray pulsar (AMXP).

When a massive star goes supernova, its core collapses into a black hole or a neutron star, which is small and superdense — around the size of a city but containing more mass than the Sun. Neutron stars are so hot the light they radiate passes red-hot, white-hot, UV-hot and enters the X-ray portion of the electromagnetic spectrum. A pulsar is a rapidly spinning neutron star.

The 2008 RXTE observation of J17062 found X-ray pulses recurring 163 times a second. These pulses mark the locations of hot spots around the pulsar’s magnetic poles, so they allow astronomers to determine how fast it’s spinning. J17062’s pulsar is rotating at about 9,800 revolutions per minute. 

Hot spots form when a neutron star’s intense gravitational field pulls material away from a stellar companion — in J17062, from the white dwarf — where it collects into an accretion disk. Matter in the disk spirals down, eventually making its way onto the surface. Neutron stars have strong magnetic fields, so the material lands on the surface of the star unevenly, traveling along the magnetic field to the magnetic poles where it creates hot spots.

The constant barrage of in-falling gas causes accreting pulsars to spin more rapidly. As they spin, the hot spots come in and out of the view of X-ray instruments like NICER, which record the fluctuations. Some pulsars rotate over 700 times per second, comparable to the blades of a kitchen blender. X-ray fluctuations from pulsars are so predictable that NICER’s companion experiment, the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT), has already shown they can serve as beacons for autonomous navigation by future spacecraft.

Over time, material from the donor star builds up on the surface of the neutron star. Once the pressure of this layer builds up to the point where its atoms fuse, a runaway thermonuclear reaction occurs, releasing the energy equivalent of 100 15-megaton bombs exploding over every square centimeter, explained Strohmayer. X-rays from such outbursts can also be captured by NICER, although one has yet to be seen from J17062.

The researchers were able to determine that J17062’s stars revolve around each other in a circular orbit, which is common for AMXPs. The white dwarf donor star is a “lightweight,” only around 1.5 percent of our Sun’s mass. The pulsar is much heavier, around 1.4 solar masses, which means the stars orbit a point around 1,900 miles (3,000 km) from the pulsar. Strohmayer said it’s almost as if the donor star orbits a stationary pulsar, but NICER is sensitive enough to detect a slight fluctuation in the pulsar’s X-ray emission due to the tug from the donor star.

“The distance between us and the pulsar is not constant,” Strohmayer said. “It’s varying by this orbital motion. When the pulsar is closer, the X-ray emission takes a little less time to reach us than when it’s further away. This time delay is small, only about 8 milliseconds for J17062's orbit, but it’s well within the capabilities of a sensitive pulsar machine like NICER.”

The results of the study were published May 9 in The Astrophysical Journal Letters.

NICER’s mission is to provide high-precision measurements to further study the physics and behavior of neutron stars. Other first-round results from the instrument have provided details about one object’s thermonuclear bursts and explored what happens to the accretion disk during these events.

“Neutron stars turn out to be truly unique nuclear physics laboratories, from a terrestrial standpoint,” said Zaven Arzoumanian, a Goddard astrophysicist and lead scientist for NICER. “We can’t recreate the conditions on neutron stars anywhere within our solar system. One of NICER’s key objectives is to study subatomic physics that isn’t accessible anywhere else.”

NICER is an Astrophysics Mission of Opportunity within NASA's Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA's Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 05/11/2018 04:14 am
The data from NICER also show J17062’s stars are only about 186,000 miles (300,000 kilometers) apart, less than the distance between Earth and the Moon. Based on the pair’s breakneck orbital period and separation, scientists involved in a new study of the system think the second star is a hydrogen-poor white dwarf.

“It’s not possible for a hydrogen-rich star, like our Sun, to be the pulsar’s companion,” said Tod Strohmayer an astrophysicist at Goddard and lead author on the paper. “You can’t fit a star like that into an orbit so small.”

But presumably the progenitor star to the pulsar must have been more massive and therefore larger (especially in its red giant phase) than the Sun, meaning the white dwarf would have been orbiting inside it? But it also needs not to accrete sufficient mass to turn it supernova.

This seems a very unusual system.
Title: Re: Astronomy Thread
Post by: deruch on 05/12/2018 01:51 am
The data from NICER also show J17062’s stars are only about 186,000 miles (300,000 kilometers) apart, less than the distance between Earth and the Moon. Based on the pair’s breakneck orbital period and separation, scientists involved in a new study of the system think the second star is a hydrogen-poor white dwarf.

“It’s not possible for a hydrogen-rich star, like our Sun, to be the pulsar’s companion,” said Tod Strohmayer an astrophysicist at Goddard and lead author on the paper. “You can’t fit a star like that into an orbit so small.”

But presumably the progenitor star to the pulsar must have been more massive and therefore larger (especially in its red giant phase) than the Sun, meaning the white dwarf would have been orbiting inside it? But it also needs not to accrete sufficient mass to turn it supernova.

This seems a very unusual system.

Maybe they captured each other after the Neutron star was created?  Otherwise, yeah.  How did that happen?
Title: Astronomy Thread
Post by: Star One on 05/13/2018 08:37 pm
UK astronomers find exoplanets with sodium, helium in atmospheres

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In the first observation of its kind, the Hubble Space Telescope has found helium in the atmosphere of a Jupiter-class exoplanet 200 lightyears from Earth. Another team of researchers, using Europe’s Very Large Telescope in Chile, has found an exoplanet, WASP-96b, with a cloud-free atmosphere, allowing them to detect sodium in levels similar to abundances on Earth.

WASP-96b orbits a star 980 lightyears away. It is similar in mass to Saturn and 20 percent larger than Jupiter. Astronomers had predicted that sodium exists in the atmospheres of such hot gas giants, but clouds would act to block such signatures.

https://astronomynow.com/2018/05/07/uk-astronomers-find-exoplanets-with-sodium-helium-in-atmospheres/ (https://astronomynow.com/2018/05/07/uk-astronomers-find-exoplanets-with-sodium-helium-in-atmospheres/)

Earth's 'Bigger, Older Cousin' Maybe Doesn't Even Exist

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Ever since astronomers started to detect planets beyond our solar system, they've been trying to find another world just like Earth. And few years ago, they announced that they'd found a planet that was the closest match yet — Kepler-452b.

Trouble is, some astronomers now say it's not possible to know for sure that this planet actually exists.

"There's new information that we can now quantify which tells us something that we didn't know before," says Fergal Mullally, who used to be an astronomer on the science team for NASA's Kepler Space Telescope.

https://www.npr.org/sections/thetwo-way/2018/05/11/609840337/earths-bigger-older-cousin-maybe-doesnt-even-exist
Title: Re: Astronomy Thread
Post by: Star One on 05/14/2018 08:38 pm

Fast Radio Bursts from the collapse of Strange Star Crusts

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Fast radio bursts (FRBs) are transient radio sources at cosmological distances. No counterparts in other bands have been observed for { non-repeating FRBs}. Here we suggest the collapse of strange star crusts as a possible origin for FRBs. Strange stars, which are composed of almost equal numbers of u, d, and s quarks, may be encapsulated by a thin crust of normal hadronic matter. When a strange star accretes matter from its environment, the crust becomes heavier and heavier. It may finally collapse, leading to the release of a large amount of magnetic energy and plenty of electron/positron pairs on a very short timescale. Electron/positron pairs in the polar cap region of the strange star can be accelerated to relativistic velocities, streaming along the magnetic field lines to form a thin shell. FRBs are produced by coherent emission from these electrons when the shell is expanding. Basic characteristics of observed FRBs can be explained in our model.

https://arxiv.org/abs/1805.04448
Title: Re: Astronomy Thread
Post by: Star One on 05/14/2018 09:02 pm
Could a multiverse be hospitable to life?

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A Multiverse - where our Universe is only one of many - might not be as inhospitable to life as previously thought, according to new research.

Questions about whether other universes might exist as part of a larger Multiverse, and if they could harbour life, are burning issues in modern cosmology.

Now new research led by Durham University, UK, and Australia's University of Sydney, Western Sydney University and the University of Western Australia, has shown that life could potentially be common throughout the Multiverse, if it exists.

https://www.eurekalert.org/pub_releases/2018-05/du-cam051018.php
Title: Astronomy Thread
Post by: Star One on 05/16/2018 07:34 pm
The first stars formed when the universe was less than 2% its current age

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Astronomers have detected a 13.3-billion-year-old oxygen signal, which suggests the first stars began forming just 250 million years after the Big Bang.

http://www.astronomy.com/news/2018/05/first-stars-from-oxygen

https://youtu.be/_spfSRxR4lQ
Title: Re: Astronomy Thread
Post by: Star One on 05/16/2018 08:16 pm
A laser from a space ant

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An international team of astronomers have discovered an unusual laser emission that suggests the presence of a double star system hidden at the heart of the "spectacular" Ant Nebula.

The extremely rare phenomenon is connected to the death of a star and was discovered in observations made by European Space Agency's (ESA) Herschel space observatory.

https://www.eurekalert.org/pub_releases/2018-05/uom-alf051618.php
Title: Re: Astronomy Thread
Post by: jebbo on 05/17/2018 07:19 pm
Tangentially related: video from Gemini Observatory's cloud camera of Kilauea erupting

https://twitter.com/quantumpenguin/status/997123063731838977?s=19 (https://twitter.com/quantumpenguin/status/997123063731838977?s=19)
Title: Re: Astronomy Thread
Post by: Star One on 05/17/2018 07:58 pm
Peering into the heart of the Milky Way

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The European Space Agency’s Planck satellite and the internationally-operated Atacama Pathfinder Experiment (APEX) combined to produce a unique view across the plane of the Milky Way showing what ESA describes as bright pockets of “compact sources of submillimetre radiation: very cold, clumpy, dusty regions that may shed light on myriad topics all the way from how individual stars form to how the entire universe is structured.” APEX, located in the Chilean Andes, is a partnership between the Max Planck Institute for Radio Astronomy, the Onasala Space Observatory and the European Southern Observatory. The Planck spacecraft was built to study the cosmic microwave background radiation left over from the big bang.

https://astronomynow.com/2018/05/15/peering-into-the-heart-of-the-milky-way/
Title: Re: Astronomy Thread
Post by: Star One on 05/17/2018 08:13 pm
Inside every proton, 10 neutron stars

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The pressure inside a single proton is enormously greater than that found inside a neutron star, according to the first measurement of the internal mechanical properties of subatomic particles.

In a study published in the journal Nature, a team headed by nuclear physicist Volker Burkert of the Thomas Jefferson National Accelerator Facility in the US reports that quarks, the building blocks of protons, are subjected to a pressure of 100 decillion pascals at the centre of the particle – about 10 times the pressure at the heart of a neutron star.

Pressure inside the particle, however, is not uniform, and drops off as the distance from the centre increases.

https://cosmosmagazine.com/physics/inside-every-proton-10-neutron-stars
Title: Re: Astronomy Thread
Post by: Star One on 05/20/2018 08:37 pm
Could recent supernovae be responsible for mass extinctions?

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Two nearby supernovae that exploded about 2.5 and eight million years ago could have resulted in a staggered depletion of Earth’s ozone layer, leading to a variety of repercussions for life on Earth.

In particular, two-and-a-half million years ago the Earth was changing dramatically. The Pliocene, which was a hot and balmy epoch, was ending and the Pleistocene, an era of repeated glaciation known as the Ice Age, was beginning. Natural variations in Earth’s orbit and wobble likely accounted for the change in climate, but the simultaneous event of a supernova could provide insight on the diversification of life during this epoch.

This supernova is thought to have occurred between 163 and 326 light years away (50–100 parsecs) from Earth. For perspective, our closest stellar neighbor, Proxima Centauri, is 4.2 light years away.

https://www.astrobio.net/news-exclusive/could-recent-supernovae-be-responsible-for-mass-extinctions/amp/
Title: Re: Astronomy Thread
Post by: jgoldader on 05/21/2018 01:06 pm
This is pretty interesting... an asteroid of possible interstellar origin has been found in a stable, retrograde solar orbit near Jupiter.  The authors' simulations show the object could have been captured during the formation of the solar system.  The actual paper is behind a paywall, unfortunately, but you can read the abstract by following a link at the end of the article below.

https://phys.org/news/2018-05-interstellar-immigrant-solar.html
Title: Astronomy Thread
Post by: Star One on 05/21/2018 03:46 pm
This is pretty interesting... an asteroid of possible interstellar origin has been found in a stable, retrograde solar orbit near Jupiter.  The authors' simulations show the object could have been captured during the formation of the solar system.  The actual paper is behind a paywall, unfortunately, but you can read the abstract by following a link at the end of the article below.

https://phys.org/news/2018-05-interstellar-immigrant-solar.html

Slightly more in-depth article with additional quotage.

This bit is worth noting.

Quote
Namouni said the asteroid is unlikely to be the solar system’s only immigrant. The computer modelling reveals that asteroids that had been captured by Jupiter but then broke free from the planet’s gravitational pull would now be orbiting the sun on a path perpendicular to the plane of the solar system. Namouni says astronomers should go on the hunt for such bodies. “When [BZ509] was captured [by Jupiter], probably it wasn’t captured all by itself, or maybe it broke up,” he said.

https://www.theguardian.com/science/2018/may/21/retrograde-asteroid-is-interstellar-immigrant-scientists-say
Title: Re: Astronomy Thread
Post by: hop on 05/21/2018 06:05 pm
This is pretty interesting... an asteroid of possible interstellar origin has been found in a stable, retrograde solar orbit near Jupiter.  The authors' simulations show the object could have been captured during the formation of the solar system.  The actual paper is behind a paywall, unfortunately, but you can read the abstract by following a link at the end of the article below.

https://phys.org/news/2018-05-interstellar-immigrant-solar.html
The argument for this being interstellar seems rather weaker than many of the headlines suggest. Some comments from other researchers in Lee Billings sciam article
https://www.scientificamerican.com/article/astronomers-spot-potential-interstellar-asteroid-orbiting-backward-around-the-sun/

Batygin of course suggests Planet 9 as an alternative ;)
Title: Re: Astronomy Thread
Post by: Star One on 05/22/2018 07:51 pm
This is pretty interesting... an asteroid of possible interstellar origin has been found in a stable, retrograde solar orbit near Jupiter.  The authors' simulations show the object could have been captured during the formation of the solar system.  The actual paper is behind a paywall, unfortunately, but you can read the abstract by following a link at the end of the article below.

https://phys.org/news/2018-05-interstellar-immigrant-solar.html
The argument for this being interstellar seems rather weaker than many of the headlines suggest. Some comments from other researchers in Lee Billings sciam article
https://www.scientificamerican.com/article/astronomers-spot-potential-interstellar-asteroid-orbiting-backward-around-the-sun/

Batygin of course suggests Planet 9 as an alternative ;)

I’ve read that article and your use of the term ‘rather weaker’ seems to me over stating what it actual argues.
Title: Re: Astronomy Thread
Post by: hop on 05/24/2018 02:54 am
The "BZ509 is interstellar" paper is now on arxiv:

An interstellar origin for Jupiter's retrograde co-orbital asteroid (https://arxiv.org/abs/1805.09013) - Fathi Namouni, Maria Helena Moreira Morais

Quote
Asteroid (514107) 2015 BZ509 was discovered recently in Jupiter's co-orbital region with a retrograde motion around the Sun. The known chaotic dynamics of the outer Solar System have so far precluded the identification of its origin. Here, we perform a high-resolution statistical search for stable orbits and show that asteroid (514107) 2015 BZ509 has been in its current orbital state since the formation of the Solar System. This result indicates that (514107) 2015 BZ509 was captured from the interstellar medium 4.5 billion years in the past as planet formation models cannot produce such a primordial large-inclination orbit with the planets on nearly-coplanar orbits interacting with a coplanar debris disk that must produce the low-inclination small-body reservoirs of the Solar System such as the asteroid and Kuiper belts. This result also implies that more extrasolar asteroids are currently present in the Solar System on nearly-polar orbits.
Title: Astronomy Thread
Post by: Star One on 05/24/2018 08:07 pm
[TORONTO] A team of astronomers has performed one of the highest resolution observations in astronomical history by observing two intense regions of radiation, 20 kilometres apart, around a star 6500 light-years away.

The observation is equivalent to using a telescope on Earth to see a flea on the surface of Pluto.

The extraordinary observation was made possible by the rare geometry and characteristics of a pair of stars orbiting each other. One is a cool, lightweight star called a brown dwarf, which features a “wake” or comet-like tail of gas. The other is an exotic, rapidly spinning star called a pulsar.

“The gas is acting like a magnifying glass right in front of the pulsar,” says Robert Main, lead author of the paper describing the observation being published May 24 in the journal Nature. “We are essentially looking at the pulsar through a naturally occurring magnifier which periodically allows us to see the two regions separately.”

Main is a PhD astronomy student in the Department of Astronomy & Astrophysics at the University of Toronto, working with colleagues at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics and Canadian Institute for Theoretical Astrophysics, and the Perimeter Institute.

The pulsar is a neutron star that rotates rapidly—over 600 times a second. As the pulsar spins, it emits beams of radiation from the two hotspots on its surface. The intense regions of radiation being observed are associated with the beams.

The brown dwarf star is about a third the diameter of the Sun. It is roughly two million kilometres from the pulsar—or five times the distance between the Earth and the moon—and orbits around it in just over 9 hours. The dwarf companion star is tidally locked to the pulsar so that one side always faces its pulsating companion, the way the moon is tidally locked to the Earth.

Because it is so close to the pulsar, the brown dwarf star is blasted by the strong radiation coming from its smaller companion. The intense radiation from the pulsar heats one side of the relatively cool dwarf star to the temperature of our Sun, or some 6000°C.

The blast from the pulsar could ultimately spell its companion’s demise. Pulsars in these types of binary systems are called “black widow” pulsars. Just as a black widow spider eats its mate, it is thought the pulsar, given the right conditions, could gradually erode gas from the dwarf star until the latter is consumed.

In addition to being an observation of incredibly high resolution, the result could be a clue to the nature of mysterious phenomena known as Fast Radio Bursts, or FRBs.

“Many observed properties of FRBs could be explained if they are being amplified by plasma lenses,” say Main. “The properties of the amplified pulses we detected in our study show a remarkable similarity to the bursts from the repeating FRB, suggesting that the repeating FRB may be lensed by plasma in its host galaxy.”

Additional notes:

1. The pulsar is designated PSR B1957+20. Previous work led by Main’s co-author, Prof. Marten van Kerkwijk, from the University of Toronto, suggests that it is likely one of the most massive pulsars known, and further work to accurately measure its mass will help in understanding how matter behaves at the highest known densities, and equivalently, how massive a neutron star can be before collapsing into a black hole.

2. Main and his co-authors used data obtained with the Arecibo Observatory radio telescope before Hurricane Maria damaged the telescope in September 2017. The collaborators will use the telescope to make follow-up observations of PSR B1957+20.

https://www.dunlap.utoronto.ca/astronomers-observe-unprecedented-detail-in-pulsar-6500-light-years-from-earth/
Title: Re: Astronomy Thread
Post by: Star One on 05/28/2018 08:13 pm
Mars rocks may harbour signs of life

Quote
The team reviewed studies of fossils on Earth and assessed the results of lab experiments replicating Martian conditions to identify the most promising sites on the planet to explore for traces of ancient life.

Their findings could help inform NASA’s next rover mission to the Red Planet, which will focus on searching for evidence of past life. The US space agency’s Mars 2020 rover will collect rock samples to be returned to Earth for analysis by a future mission.

A similar mission led by the European Space Agency is also planned in coming years.

The latest study could aid in the selection of landing sites for both missions, and help identify the best places to gather rock samples.

The study, published in Journal of Geophysical Research, also involved researchers at NASA’s Jet Propulsion Laboratory, Brown University, California Institute of Technology, Massachusetts Institute of Technology and Yale University in the US.

https://www.ed.ac.uk/news/2018/mars-rocks-may-harbour-signs-of-life
Title: Re: Astronomy Thread
Post by: Star One on 05/30/2018 08:22 pm
Does Some Dark Matter Carry an Electric Charge?

Quote
Astronomers have proposed a new model for the invisible material that makes up most of the matter in the Universe. They have studied whether a fraction of dark matter particles may have a tiny electrical charge.

"You've heard of electric cars and e-books, but now we are talking about electric dark matter," said Julian Munoz of Harvard University in Cambridge, Mass., who led the study that has been published in the journal Nature. "However, this electric charge is on the very smallest of scales."

Munoz and his collaborator, Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., explore the possibility that these charged dark matter particles interact with normal matter by the electromagnetic force.

https://www.cfa.harvard.edu/news/2018-08
Title: Re: Astronomy Thread
Post by: Blackstar on 05/31/2018 01:20 pm
Next astro decadal will not be delayed:

http://spacenews.com/nasa-drops-request-to-delay-next-astrophysics-decadal/
Title: Re: Astronomy Thread
Post by: Kesarion on 05/31/2018 06:07 pm
Next astro decadal will not be delayed:

http://spacenews.com/nasa-drops-request-to-delay-next-astrophysics-decadal/


Interesting quote from the article:

Quote
He added he was also concerned that the decadal, whenever it takes place, reflect the diversity of the astrophysics research community. “[A] strategy cannot be important if it is put together by representatives of the top-10 University programs, and by a community group that is all male and has an average age north of 65!” he wrote. “Diverse groups make better strategies, and provide better alignment and buy-in.”

I know this is a sensible topic, so I'll try my best to communicate as civil as possible my worries.

I thought the general unspoken rule for scientist was to not insert their personal politics in their methodology.
Considering the fact that we are talking about multibillion dollar endeavors payed for by taxpayer money you would think the first concern should be to get the most qualified (based on academic merit and prior experience) persons to design these missions and bot prioritize based on arbitrary ideological reasoning, like gender, age or ethnicity.
For example, I don't think it's wise to try to give equal say in planning between a 24 yr old undergrad and a 68 yr old who was involved in several other missions.

We already know how some of these flagship telescopes can have their costs balloon out of control (looking at you JWST), I don't think the science directorate has any wiggle room to reject certain participants because they are male or over 65 if they prove to be the most qualified to carry a given task.


I am worried about this kind of reasoning because over the last to years there have been a couple of times when the same "issue" was brought up at different meetings, and I was wondering if there is any backlash within the astrophysics and planetary scientific communities for what (to me at least) looks like a dangerous pushing of a fringe political dogma in government funded science. 


I know that those soon to retire might be somewhat indifferent, but I am curious if the younger counterparts are worried about possible discrimination and questioning this push for diversity became taboo.
Title: Re: Astronomy Thread
Post by: Star One on 05/31/2018 07:24 pm
Next astro decadal will not be delayed:

http://spacenews.com/nasa-drops-request-to-delay-next-astrophysics-decadal/


Interesting quote from the article:

Quote
He added he was also concerned that the decadal, whenever it takes place, reflect the diversity of the astrophysics research community. “[A] strategy cannot be important if it is put together by representatives of the top-10 University programs, and by a community group that is all male and has an average age north of 65!” he wrote. “Diverse groups make better strategies, and provide better alignment and buy-in.”

I know this is a sensible topic, so I'll try my best to communicate as civil as possible my worries.

I thought the general unspoken rule for scientist was to not insert their personal politics in their methodology.
Considering the fact that we are talking about multibillion dollar endeavors payed for by taxpayer money you would think the first concern should be to get the most qualified (based on academic merit and prior experience) persons to design these missions and bot prioritize based on arbitrary ideological reasoning, like gender, age or ethnicity.
For example, I don't think it's wise to try to give equal say in planning between a 24 yr old undergrad and a 68 yr old who was involved in several other missions.

We already know how some of these flagship telescopes can have their costs balloon out of control (looking at you JWST), I don't think the science directorate has any wiggle room to reject certain participants because they are male or over 65 if they prove to be the most qualified to carry a given task.


I am worried about this kind of reasoning because over the last to years there have been a couple of times when the same "issue" was brought up at different meetings, and I was wondering if there is any backlash within the astrophysics and planetary scientific communities for what (to me at least) looks like a dangerous pushing of a fringe political dogma in government funded science. 


I know that those soon to retire might be somewhat indifferent, but I am curious if the younger counterparts are worried about possible discrimination and questioning this push for diversity became taboo.

I really do wish you hadn’t opened this particular can of worms as identity politics is a hot button topic at the moment and I don’t want this thread descending into a political civil war. So could you not possibly start a thread in political policy which is where if anywhere this topic belongs.
Title: Re: Astronomy Thread
Post by: Kesarion on 05/31/2018 08:31 pm
So could you not possibly start a thread in political policy which is where if anywhere this topic belongs.

Urm, is the use of the word "not" intentional because I'm not sure I understand.

Regardless, I agree that it is a rather off topic conversation for this thread, so it shouldn't be expanded here.


However, this has been a theme in the last couple of years and has been bugging me because no one seemed to even acknowledge it.

Don't get me wrong, I don't want to be that guy who creates political conflict in topics like this, that is not my intent. I have tremendous respect and admiration for the work done by all scientists and engineers working for these observatories, regardless of their personal characteristics or beliefs.

Considering the fact the next flagship after WFIRST (LUVOIR, HabEx, LYNX, Origins) might very well be the most expensive and complex telescope ever launched, one can not help but be a litle worried about the wish of some higherups to select teams based on reasons other than pure merit.


JWST went through a lot of problems troughout the last decade, in part to a lack of rigorous managment, I don't think adding an extra layer of complexity will do any favour to american astrophysics in the next 10-20 years, so that's why I brought such a delicate issue in the first place.


Case in point, I do agree that this conversation needs its own separate thread.


 
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 05/31/2018 11:08 pm
A paper on the possibilities of exomoons in habitable zones:

Exploring Kepler Giant Planets in the Habitable Zone (https://arxiv.org/abs/1805.03370) (arXiv)

Quote
(Abstract)
The Kepler mission found hundreds of planet candidates within the habitable zones (HZ) of their host star, including over 70 candidates with radii larger than 3 Earth radii (R⊕) within the optimistic habitbale zone (OHZ) (Kane et al. 2016). These giant planets are potential hosts to large terrestrial satellites (or exomoons) which would also exist in the HZ. We calculate the occurrence rates of giant planets (Rp=~3.0--25~R⊕) in the OHZ and find a frequency of (6.5±1.9)% for G stars, (11.5±3.1)% for K stars, and (6±6)% for M stars. We compare this with previously estimated occurrence rates of terrestrial planets in the HZ of G, K and M stars and find that if each giant planet has one large terrestrial moon then these moons are less likely to exist in the HZ than terrestrial planets. However, if each giant planet holds more than one moon, then the occurrence rates of moons in the HZ would be comparable to that of terrestrial planets, and could potentially exceed them. We estimate the mass of each planet candidate using the mass-radius relationship developed by Chen & Kipping (2016). We calculate the Hill radius of each planet to determine the area of influence of the planet in which any attached moon may reside, then calculate the estimated angular separation of the moon and planet for future imaging missions. Finally, we estimate the radial velocity semi-amplitudes of each planet for use in follow up observations.
Title: Re: Astronomy Thread
Post by: Star One on 06/01/2018 05:11 pm
The habitability of the Milky Way during the active phase of its central supermassive black hole

Quote
During the peak of their accretion phase, supermassive black holes in galactic cores are known to emit very high levels of ionizing radiation, becoming visible over intergalactic distances as quasars or active galactic nuclei (AGN). Here, we quantify the extent to which the activity of the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*), may have affected the habitability of Earth-like planets in our Galaxy. We focus on the amount of atmospheric loss and on the possible biological damage suffered by planets exposed to X-ray and extreme ultraviolet (XUV) radiation produced during the peak of the active phase of Sgr A*. We find that terrestrial planets could lose a total atmospheric mass comparable to that of present day Earth even at large distances (~1 kiloparsec) from the galactic center. Furthermore, we find that the direct biological damage caused by Sgr A* to surface life on planets not properly screened by an atmosphere was probably significant during the AGN phase, possibly hindering the development of complex life within a few kiloparsecs from the galactic center.

https://www.nature.com/articles/s41598-017-16110-0
Title: Re: Astronomy Thread
Post by: Star One on 06/01/2018 08:10 pm
Computer simulations suggest reason for strange moon shapes

Quote
The small, inner moons of Saturn have intriguing shapes resembling in some cases ravioli and spaetzle. Just how they came to resemble giant pieces of pasta has been a mystery, but new computer simulations show they likely formed when smaller moons collided in the extreme tidal environment close to the ringed planet.

It all started when Martin Rubin, an astrophysicist at the University of Bern, saw closeup pictures of Saturn’s moons Atlas and Pan that were taken by the Cassini orbiter in 2017. They featured large ridges and central bulges that gave them the appearance of huge flying saucers.

https://youtu.be/SIy-d9gDrrU

https://astronomynow.com/2018/05/22/computer-simulations-suggest-reason-for-strange-moon-shapes/
Title: Re: Astronomy Thread
Post by: Star One on 06/01/2018 08:38 pm
Multiple metals – and possible signs of water – found in unique exoplanet

Quote
The team, from the University of Cambridge and the Instituto de Astrofísica de Canarias (IAC) in Spain, used the Gran Telescopio Canarias (GTC) to observe WASP-127b, a giant gaseous planet with partly clear skies and strong signatures of metals in its atmosphere. The results have been accepted for publication in the journal Astronomy & Astrophysics.

WASP-127b has a radius 1.4 times larger than Jupiter but has only 20% of its mass. Such a planet has no analogue in our solar system and is rare even within the thousands of exoplanets discovered to date. It takes just over four days to orbit its parent star and its surface temperature is around 1400 K (1127° C).

The observations of WASP-127b reveal the presence of a large concentration of alkali metals in its atmosphere, allowing simultaneous detections of sodium, potassium and lithium for the first time in an exoplanet. The sodium and potassium absorptions are very broad, which is characteristic of relatively clear atmospheres. According to modelling work done by the researchers, the skies of WASP-127b are approximately 50% clear.

https://phys.org/news/2018-06-multiple-metals-unique-exoplanet.amp

Title: Re: Astronomy Thread
Post by: Kesarion on 06/04/2018 03:48 pm
NASA imposes cost caps on astrophysics flagship studies

Quote
In a May 31 statement, NASA said it has instructed the four teams studying proposed missions for consideration by the 2020 decadal survey to “narrow the scope” of their concepts so that their total cost is between $3 billion and $5 billion. That new cap, the statement said, reflected “current and anticipated budget constraints” for the agency’s astrophysics programs.

Quote
At least one of the four mission studies, though, claims to be exempt from this new directive. The Large UV/Optical/IR Surveyor (LUVOIR) mission would develop a space telescope with a primary mirror up to 15 meters in diameter, intended to support a broad range of astronomical research in ultraviolet through infrared wavelengths.[…] In a statement posted to its website, the LUVOIR team acknowledged that it and the other study teams received instructions from NASA Headquarters “to produce versions of their concepts that fit into the $3-5B cost box.” However, it added, “LUVOIR was exempt from this instruction.” It didn’t explain why and how it was granted an exemption.

http://spacenews.com/nasa-imposes-cost-caps-on-astrophysics-flagship-studies/
Title: Re: Astronomy Thread
Post by: Star One on 06/04/2018 08:48 pm
Tiny Asteroid Discovered Saturday Disintegrates Hours Later Over Southern Africa

Quote
"The discovery of asteroid 2018 LA is only the third time that an asteroid has been discovered to be on an impact trajectory, said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL. "It is also only the second time that the high probability of an impact was predicted well ahead of the event itself."

https://www.jpl.nasa.gov/news/news.php?release=2018-124&rn=news.xml&rst=7148

NEOWISE Thermal Data Reveal Surface Properties of Over 100 Asteroids

https://www.jpl.nasa.gov/news/news.php?release=2018-122&rn=news.xml&rst=7146

Globular clusters 4 billion years younger than previously thought

Quote
Globular clusters could be up to 4 billion years younger than previously thought, new research led by the University of Warwick has found

https://www.eurekalert.org/pub_releases/2018-06/uow-gc4060418.php

Chemical traces from star formation cast light on cosmic history

https://www.eurekalert.org/pub_releases/2018-06/uoe-ctf060418.php
Title: Re: Astronomy Thread
Post by: Star One on 06/05/2018 07:48 pm
Okay, Last Year’s Kilonova Did Probably Create a Black Hole

Quote
This source, known as GW170817/GRB, has been the target of many follow-up surveys since it was believed that the merge could have led to the formation of a black hole. According to a new study by a team that analyzed data from NASA’s Chandra X-ray Observatory since the event, scientists can now say with greater confidence that the merger created a new black hole in our galaxy.

The study, titled “GW170817 Most Likely Made a Black Hole“, recently appeared in The Astrophysical Journal Letters. The study was led by David Pooley, an assistant professor in physics and astronomy at Trinity University, San Antonio, and included members from the University of Texas at Austin, the University of California, Berkeley, and Nazarbayev University’s Energetic Cosmos Laboratory in Kazakhstan.

https://www.universetoday.com/139366/okay-last-years-kilonova-did-probably-create-a-black-hole/amp/
Title: Re: Astronomy Thread
Post by: Star One on 06/06/2018 08:01 pm
Collisions of Dead Stars Spray Heavy Elements Throughout Small Galaxies

Quote
Caltech scientists have found, for the first time, that merging pairs of neutron stars—the burnt-out cores of stars that have exploded—create the majority of heavy elements in small "dwarf" galaxies. Heavy elements, such as silver and gold, are key for planet formation and even life itself. By studying these dwarf galaxies, the researchers hope to learn more about the primary sources of heavy elements for the whole universe.

http://m.caltech.edu/news/collisions-dead-stars-spray-heavy-elements-throughout-small-galaxies-82434
Title: Re: Astronomy Thread
Post by: Star One on 06/06/2018 10:45 pm
One of the Three Closest Stars Looks Friendly for Life

Quote
Alpha Centauri A may be even less deadly than the sun—if there are any planets there.

https://www.popularmechanics.com/space/deep-space/a21098815/biggest-star-alpha-centauri-system-friendliest-to-life/
Title: Astronomy Thread
Post by: Star One on 06/12/2018 08:14 pm
Astronauts' movement increased subsurface temperatures on the moon, study finds

Quote
It may have been one giant leap for man, but those steps may have consequences for mankind.

The presence of astronauts on the moon caused an unexpected warming of its subsurface temperatures for a period of time in the 1970s, a new study has found after delving into "lost" tapes from the Apollo missions.

https://www.cbc.ca/amp/1.4697741?

'Surprisingly fast' recovery of life at dinosaur-killing asteroid impact site

Quote
Within 30,000 years of impact, Mexico’s Chicxulub crater fostered a thriving ecosystem - a much faster recovery than many sites around the world.

https://www.imperial.ac.uk/news/186670/surprisingly-fast-recovery-life-dinosaur-killing-asteroid/

Mineralogy on Mars points to a cold and icy ancient climate

Quote
WEST LAFAYETTE, Ind. — The climate throughout Mars’ early history has long been debated – was the Red Planet warm and wet, or cold and icy? New research published in Icarus provides evidence for the latter.

https://www.purdue.edu/newsroom/releases/2018/Q2/minerology-on-mars-points-to-a-cold-and-icy-ancient-climate.html

Diamond Dust Shimmering around Distant Stars:
Nanoscale gemstones source of mysterious cosmic microwave light


Quote
Some of the tiniest diamonds in the universe – bits of crystalline carbon hundreds of thousands of times smaller than a grain of sand – have been detected swirling around three infant star systems in the Milky Way. These microscopic gemstones are neither rare nor precious; they are, however, exciting for astronomers who identified them as the source of a mysterious cosmic microwave “glow” emanating from several protoplanetary disks in our galaxy.

http://greenbankobservatory.org/press/diamond-dust.html
Title: Re: Astronomy Thread
Post by: Star One on 06/13/2018 07:52 pm
ALMA Discovers Trio of Infant Planets around Newborn Star

Quote
Two independent teams of astronomers have used ALMA to uncover convincing evidence that three young planets are in orbit around the infant star HD 163296. Using a novel planet-finding technique, the astronomers identified three disturbances in the gas-filled disc around the young star: the strongest evidence yet that newly formed planets are in orbit there. These are considered the first planets to be discovered with ALMA.

http://www.eso.org/public/news/eso1818/
Title: Re: Astronomy Thread
Post by: Star One on 06/14/2018 07:53 pm
New Constraints on the Abundance and Composition of Organic Matter on Ceres

Quote
Near‐infrared reflectance spectra from the Dawn mission at Ceres were recently found to exhibit a 3.4 μm absorption indicative of the presence of aliphatic organic compounds. Constraints on abundance and composition of these organics are necessary to inform discussions of their origin. We model reflectance spectra of organic‐bearing regions on Ceres using laboratory spectra of insoluble organics of known composition extracted from terrestrial sedimentary rocks (i.e., kerogens) and carbonaceous chondrite meteorites (i.e., insoluble organic matter, IOM). The 3.4 μm aliphatic organic absorptions observed in Dawn near‐infrared data are stronger than those observed in lab spectra of carbonaceous chondrites, and modeling requires 45% to 65% spectral fraction of IOM to fit spectra from Ceres. The spectral fraction of kerogen necessary to fit the same Ceres spectra ranges from 5% to 15% depending on the hydrogen to carbon ratio of the kerogen. Any proposed mechanism of organic delivery or formation on Ceres should explain the presence of highly concentrated IOM or why the composition is distinct from meteorite‐derived IOM if lower organic abundances are considered more plausible.

Plain Language Summary
Organics were recently detected on the dwarf planet Ceres with infrared spectroscopy. The origin of these organics is, as yet, unknown. Using laboratory spectra of terrestrial and extraterrestrial (meteorite‐derived) organic materials with known composition, we reanalyze the Ceres spectra to constrain composition and abundance of those organics. Such constraints could help us discern whether these organics formed on Ceres or were delivered by an impactor.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077913
Title: Re: Astronomy Thread
Post by: Star One on 06/14/2018 09:25 pm
Computational models show that planets can easily exist in triple star systems

https://www.wits.ac.za/news/latest-news/research-news/2018/2018-06/computational-models-show-that-planets-can-easily-exist-in-triple-star-systems.html
Title: Re: Astronomy Thread
Post by: Star One on 06/15/2018 06:41 am
A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger

Quote
Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg in the infrared and radio but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH.

http://science.sciencemag.org/content/early/2018/06/13/science.aao4669
Title: Re: Astronomy Thread
Post by: Star One on 06/15/2018 08:02 pm
Long suspected theory about the Moon holds water

Quote
A team of Japanese scientists led by Masahiro Kayama of Tohoku University's Frontier Research Institute for Interdisciplinary Sciences, has discovered a mineral known as moganite in a lunar meteorite found in a hot desert in northwest Africa.

This is significant because moganite is a mineral that requires water to form, reinforcing the belief that water exists on the Moon.

"Moganite is a crystal of silicon dioxide and is similar to quartz. It forms on Earth as a precipitate when alkaline water including SiO2 is evaporated under high pressure conditions," says Kayama. "The existence of moganite strongly implies that there is water activity on the Moon."

https://www.tohoku.ac.jp/en/press/moon_holds_water.html
Title: Re: Astronomy Thread
Post by: Star One on 06/18/2018 08:36 pm
EXPLOSIVE VOLCANOES SPAWNED MYSTERIOUS MARTIAN ROCK FORMATION

Quote
Explosive volcanic eruptions that shot jets of hot ash, rock and gas skyward are the likely source of a mysterious Martian rock formation, a new study finds. The new finding could add to scientists’ understanding of Mars’s interior and its past potential for habitability, according to the study’s authors.

The Medusae Fossae Formation is a massive, unusual deposit of soft rock near Mars’s equator, with undulating hills and abrupt mesas. Scientists first observed the Medusae Fossae with NASA’s Mariner spacecraft in the 1960s but were perplexed as to how it formed.

https://news.agu.org/press-release/explosive-volcanoes-spawned-mysterious-martian-rock-formation/
Title: Re: Astronomy Thread
Post by: Star One on 06/20/2018 08:00 pm
A possible explanation for varying measurements of Venus's rotation rate

Quote
A trio of researchers with the University of California and Sorbonne Universités has found a possible explanation for why Venus probes have found different day lengths for the planet. In their paper published in the journal Nature Geoscience, T. Navarro, G. Schubert and S. Lebonnois describe a theory they have developed based on observational data.

https://phys.org/news/2018-06-explanation-varying-venus-rotation.amp?
Title: Re: Astronomy Thread
Post by: redliox on 06/20/2018 11:50 pm
A possible explanation for varying measurements of Venus's rotation rate

Quote
A trio of researchers with the University of California and Sorbonne Universités has found a possible explanation for why Venus probes have found different day lengths for the planet. In their paper published in the journal Nature Geoscience, T. Navarro, G. Schubert and S. Lebonnois describe a theory they have developed based on observational data.

https://phys.org/news/2018-06-explanation-varying-venus-rotation.amp?

So Venus' own winds might have slowed and warped its rotation?
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 06/22/2018 01:41 am
A possible explanation for varying measurements of Venus's rotation rate

Quote
A trio of researchers with the University of California and Sorbonne Universités has found a possible explanation for why Venus probes have found different day lengths for the planet. In their paper published in the journal Nature Geoscience, T. Navarro, G. Schubert and S. Lebonnois describe a theory they have developed based on observational data.

https://phys.org/news/2018-06-explanation-varying-venus-rotation.amp?

So Venus' own winds might have slowed and warped its rotation?

As the planet and its atmosphere are for this purpose a closed system, angular momentum is conserved. The mass of the atmosphere will carry proportionally more angular momentum than the mass of the planet because it is further from the axis of rotation and has a higher angular velocity (it goes around the planet up to 60 times faster than the planet itself rotates). So, as average wind speeds in the direction of rotation pick up the planet will slow down and as the winds die down the planet will speed up. The only question is how big is the effect.
Title: Re: Astronomy Thread
Post by: jebbo on 06/22/2018 08:03 am
A very interesting discovery from Gaia:

A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2

We present the discovery of a gap near MG≈10 in the main sequence on the Hertzsprung-Russell Diagram (HRD) based on measurements presented in Gaia Data Release 2 (DR2). Using an observational form of the HRD with MG representing luminosity and GBP−GRP representing temperature, the gap presents a diagonal feature that dips toward lower luminosities at redder colors. The gap is seen in samples extracted from DR2 with various distances, and is not unique to the {\it Gaia} photometry --- it also appears when using near-IR photometry (J−Ks vs MKs). The gap is very narrow (∼0.05 mag) and is near the luminosity-temperature regime where M dwarf stars transition from partially to fully convective, i.e., near spectral type M3.0V. This gap provides a new feature in the H-R Diagram that hints at an underlying astrophysical cause and we propose that it is linked to the onset of full convection in M dwarfs.

https://arxiv.org/abs/1806.07792 (https://arxiv.org/abs/1806.07792)
Title: Re: Astronomy Thread
Post by: Star One on 06/22/2018 08:30 am
A very interesting discovery from Gaia:

A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2

We present the discovery of a gap near MG≈10 in the main sequence on the Hertzsprung-Russell Diagram (HRD) based on measurements presented in Gaia Data Release 2 (DR2). Using an observational form of the HRD with MG representing luminosity and GBP−GRP representing temperature, the gap presents a diagonal feature that dips toward lower luminosities at redder colors. The gap is seen in samples extracted from DR2 with various distances, and is not unique to the {\it Gaia} photometry --- it also appears when using near-IR photometry (J−Ks vs MKs). The gap is very narrow (∼0.05 mag) and is near the luminosity-temperature regime where M dwarf stars transition from partially to fully convective, i.e., near spectral type M3.0V. This gap provides a new feature in the H-R Diagram that hints at an underlying astrophysical cause and we propose that it is linked to the onset of full convection in M dwarfs.

https://arxiv.org/abs/1806.07792 (https://arxiv.org/abs/1806.07792)

The significance of this being?
Title: Re: Astronomy Thread
Post by: zubenelgenubi on 06/22/2018 12:13 pm
A very interesting discovery from Gaia:

A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2

We present the discovery of a gap near MG≈10 in the main sequence on the Hertzsprung-Russell Diagram (HRD) based on measurements presented in Gaia Data Release 2 (DR2). Using an observational form of the HRD with MG representing luminosity and GBP−GRP representing temperature, the gap presents a diagonal feature that dips toward lower luminosities at redder colors. The gap is seen in samples extracted from DR2 with various distances, and is not unique to the {\it Gaia} photometry --- it also appears when using near-IR photometry (J−Ks vs MKs). The gap is very narrow (∼0.05 mag) and is near the luminosity-temperature regime where M dwarf stars transition from partially to fully convective, i.e., near spectral type M3.0V. This gap provides a new feature in the H-R Diagram that hints at an underlying astrophysical cause and we propose that it is linked to the onset of full convection in M dwarfs.

https://arxiv.org/abs/1806.07792 (https://arxiv.org/abs/1806.07792)

The significance of this being?

Observational confirmation of stellar modelling, I presume.  Astrophysicists never had the data to confirm the stellar modelling of this transition before because the necessary spectroscopy didn't exist--finding red dwarfs that faint, in a sufficient quantity to be statistically significant, and then obtaining detailed spectrographs from such faint sources.  (Greater detail than that necessary to derive a spectral type.)

It appears that the photometry in multiple spectral bands is substituting for detailed spectrography.

If I remember correctly, the fuller the convection is within a star, the more of its total mass is available for fusion at the core.  Red dwarfs "process" at a very slow rate, so they are modelled to live on the main sequence--fusing hydrogen to helium--for an incredible length of time--tens to hundreds of billions of years.

Full convection means the entire star's mass is available, stretching the main sequence lifetime even more.  (I don't recall how much more.)
Title: Re: Astronomy Thread
Post by: Star One on 06/23/2018 08:25 pm
The Solar Twin Planet Search: The age - chromospheric activity relation

It is well known that the magnetic activity of solar type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1-2 Gyr followed by a relatively inactive constant phase. We revisited the activity-age relation using time-series observations of a large sample of solar twins whose precise isochronal ages and other important physical parameters have been determined. We measured the Ca II H and K activity indices using 9000 HARPS spectra of 82 solar twins. We measured an average solar activity of  SMW  = 0.1712 ± 0.0017 during solar magnetic cycles 23−24 covered by HARPS observations and we also inferred an average of SMW = 0.1694 ± 0.0025 for cycles 10−24, anchored on a S index vs. sunspot number correlation. Also, a simple relation between the average and dispersion of the activity levels of solar twins was found. This enabled us to predict the stellar variability effects on the age-activity diagram and, consequently, estimate the chromospheric age uncertainties due to the same phenomena. The age-activity relation is still statistically significant up to ages around 6−7 Gyr, in agreement with previous works using open clusters and field stars with precise ages. Our research confirms that Ca II H \& K lines remain a useful chromospheric evolution tracer until stars reach ages of at least 6−7 Gyr. We found an evidence that, for the most homogeneous set of old stars, the chromospheric activity indices seem to continue decreasing after the solar age towards the end of the main-sequence. Our results indicate that a significant part of the scatter observed in the age-activity relation of solar twins can be attributed to stellar cycle modulations effects. The Sun seems to have a normal activity level and variability for its age.

https://arxiv.org/abs/1806.08014
Title: Astronomy Thread
Post by: Star One on 06/23/2018 08:35 pm
New experiment to probe dark matter interactions

https://astronomynow.com/2018/06/17/new-experiment-to-probe-dark-matter-interactions/

Where does Titan Sand Come From: Insight from Mechanical Properties of Titan Sand Candidates

Extensive equatorial linear dunes exist on Titan, but the origin of the sand, which appears to be organic, is unknown. We used nanoindentation to study the mechanical properties of a few Titan sand candidates, several natural sands on Earth, and common materials used in the Titan Wind Tunnel, to understand the mobility of Titan sand. We measured the elastic modulus (E), hardness (H), and fracture toughness (Kc) of these materials. Tholin's elastic modulus (10.4+/-0.5 GPa) and hardness (0.53+/-0.03 GPa) are both an order of magnitude smaller than silicate sand, and is also smaller than the mechanically weak white gypsum sand. With a magnitude smaller fracture toughness (Kc=0.036+/-0.007 MPa-m^(1/2)), tholin is also much more brittle than silicate sand. This indicates that Titan sand should be derived close to the equatorial regions where the current dunes are located, because tholin is too soft and brittle to be transported for long distances.

https://arxiv.org/abs/1806.08056
Title: Re: Astronomy Thread
Post by: theinternetftw on 06/24/2018 02:40 am
Awesome.  A little more on the Titan Wind Tunnel (w/ picture):
https://www.hou.usra.edu/meetings/lpsc2016/pdf/2356.pdf

And planetary wind tunnels in general:
https://www.nasa.gov/ames/planetary-aeolian-laboratory

The Planetary Society also has a great article on tholins:
http://www.planetary.org/blogs/guest-blogs/2015/0722-what-in-the-worlds-are-tholins.html
Title: Re: Astronomy Thread
Post by: Star One on 06/26/2018 07:54 pm
New SPHERE view of Vesta

Quote
Vesta was recently observed by the SPHERE/ZIMPOL instrument on ESO’s Very Large Telescope (VLT) — the SPHERE image is shown on the left, produced using the MISTRAL algorithm, with a synthetic view derived from space-based data shown on the right for comparison. SPHERE, the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument, is a powerful planet-finding and direct imaging instrument. ZIMPOL is one of its subsystems: a specialised camera perfectly suited to taking very sharp images of small objects — like Vesta.

http://www.eso.org/public/images/potw1826a/
Title: Re: Astronomy Thread
Post by: Star One on 06/27/2018 05:16 pm
Apparently space is full of enough grease for 40 trillion trillion trillon packs of butter.

Quote
It looks cold, dark and empty, but astronomers have revealed that interstellar space is permeated with a fine mist of grease-like molecules.
The study provides the most precise estimate yet of the amount of “space grease” in the Milky Way, by recreating the carbon-based compounds in the laboratory. The Australian-Turkish team discovered more than expected: 10 billion trillion trillion tonnes of gloop, or enough for 40 trillion trillion trillion packs of butter.
Prof Tim Schmidt, a chemist at the University of New South Wales, Sydney and co-author of the study, said that the windscreen of a future spaceship travelling through interstellar space might be expected to get a sticky coating.
“Amongst other stuff it’ll run into is interstellar dust, which is partly grease, partly soot and partly silicates like sand,” he said, adding that the grease is swept away within our own solar system by the solar wind.

https://www.theguardian.com/science/2018/jun/27/space-is-full-of-dirty-toxic-grease-scientists-reveal
Title: Re: Astronomy Thread
Post by: Star One on 06/27/2018 08:50 pm
Complex molecules found on Enceladus

Quote
The discovery of complex organic molecules on Enceladus makes Saturn's moon the only known body apart from Earth to satisfy the requirements for life as we know it.

http://m.skyatnightmagazine.com/news/complex-organic-molecules-found-moon-enceladus
Title: Astronomy Thread
Post by: Star One on 07/02/2018 11:33 am
First confirmed image of a newborn planet revealed

Quote
Nascent planet seen carving a path through the disc of gas and dust surrounding the very young star PDS70

Quote
Captured by the Sphere instrument of the European Southern Observatory’s Very Large Telescope, the planet – a gas giant with a mass greater than Jupiter – is about as far from its star as Uranus is from our sun, with further analyses revealing that it appears to have a cloudy atmosphere and a surface temperature of 1000C.

Quote
“The special thing about this new planet is that we can directly image it, so the ones by Kepler, for example, they were derived by indirect techniques,” she told the Guardian. “In this case we now have a direct image [of the planet] in its “birthplace”, which is the circumstellar disc. This is especially important because people have been wondering [for a long time], how these planets actually form and how the dust and the material in this disc forms [into] a planet, and now we can directly observe this.”

https://www.theguardian.com/science/2018/jul/02/first-confirmed-image-of-a-newborn-planet-revealed-pds70

https://www.youtube.com/watch?v=JYCKQWEOywY

ESOcast 169.
Title: Re: Astronomy Thread
Post by: Star One on 07/04/2018 08:14 pm
Einstein gets it right again—weak and strong gravity objects fall the same way

Quote
In 2011, the National Science Foundation's (NSF) Green Bank Telescope (GBT) discovered a natural laboratory to test this theory in extreme conditions: a triple star system called PSR J0337+1715, located about 4,200 light-years from Earth. This system contains a neutron star in a 1.6-day orbit with a white dwarf star, and the pair in a 327-day orbit with another white dwarf further away.

Quote
Through meticulous observations and careful calculations, the team was able to test the system's gravity using the pulses of the neutron star alone. They found that any acceleration difference between the neutron star and inner white dwarf is too small to detect.

"If there is a difference, it is no more than three parts in a million," said coauthor Nina Gusinskaia of the University of Amsterdam. This places severe constraints on any alternative theories to general relativity.

This result is ten times more precise that the previous best test of gravity, making the evidence for Einstein's Strong Equivalence Principle that much stronger. "We're always looking for better measurements in new places, so our quest to learn about new frontiers in our Universe is going to continue," concluded Ransom.

https://m.phys.org/news/2018-07-einstein-againweak-strong-gravity-fall.html

Title: Re: Astronomy Thread
Post by: CuddlyRocket on 07/05/2018 09:24 am
The gravitational mass of Proxima Centauri measured with SPHERE from a microlensing event (https://arxiv.org/abs/1807.01318) (arXiv preprint)

Quote
(Abstract)
Proxima Centauri, our closest stellar neighbour, is a low-mass M5 dwarf orbiting in a triple system. An Earth-mass planet with an 11 day period has been discovered around this star. The star's mass has been estimated only indirectly using a mass-luminosity relation, meaning that large uncertainties affect our knowledge of its properties. To refine the mass estimate, an independent method has been proposed: gravitational microlensing. By taking advantage of the close passage of Proxima Cen in front of two background stars, it is possible to measure the astrometric shift caused by the microlensing effect due to these close encounters and estimate the gravitational mass of the lens (Proxima Cen). Microlensing events occurred in 2014 and 2016 with impact parameters, the closest approach of Proxima Cen to the background star, of 1\farcs6 ± 0\farcs1 and 0\farcs5 ± 0\farcs1, respectively. Accurate measurements of the positions of the background stars during the last two years have been obtained with HST/WFC3, and with VLT/SPHERE from the ground. The SPHERE campaign started on March 2015, and continued for more than two years, covering 9 epochs. The parameters of Proxima Centauri's motion on the sky, along with the pixel scale, true North, and centering of the instrument detector were readjusted for each epoch using the background stars visible in the IRDIS field of view. The experiment has been successful and the astrometric shift caused by the microlensing effect has been measured for the second event in 2016. We used this measurement to derive a mass of 0.150+0.062−0.051 (an error of ∼ 40\%) \MSun for Proxima Centauri acting as a lens. This is the first and the only currently possible measurement of the gravitational mass of Proxima Centauri.

This new value of the star's mass raises the msini mass of the planet from 1.27 to 1.56 times the mass of the Earth.

Technically, the 'gravitational mass' is the mass of the star plus the planet and everything else in the stellar system. However, Proxima Centauri is about 20,000 times the mass of its known planet, so that's a small correction at present.
Title: Re: Astronomy Thread
Post by: Star One on 07/05/2018 10:36 am
The gravitational mass of Proxima Centauri measured with SPHERE from a microlensing event (https://arxiv.org/abs/1807.01318) (arXiv preprint)

Quote
(Abstract)
Proxima Centauri, our closest stellar neighbour, is a low-mass M5 dwarf orbiting in a triple system. An Earth-mass planet with an 11 day period has been discovered around this star. The star's mass has been estimated only indirectly using a mass-luminosity relation, meaning that large uncertainties affect our knowledge of its properties. To refine the mass estimate, an independent method has been proposed: gravitational microlensing. By taking advantage of the close passage of Proxima Cen in front of two background stars, it is possible to measure the astrometric shift caused by the microlensing effect due to these close encounters and estimate the gravitational mass of the lens (Proxima Cen). Microlensing events occurred in 2014 and 2016 with impact parameters, the closest approach of Proxima Cen to the background star, of 1\farcs6 ± 0\farcs1 and 0\farcs5 ± 0\farcs1, respectively. Accurate measurements of the positions of the background stars during the last two years have been obtained with HST/WFC3, and with VLT/SPHERE from the ground. The SPHERE campaign started on March 2015, and continued for more than two years, covering 9 epochs. The parameters of Proxima Centauri's motion on the sky, along with the pixel scale, true North, and centering of the instrument detector were readjusted for each epoch using the background stars visible in the IRDIS field of view. The experiment has been successful and the astrometric shift caused by the microlensing effect has been measured for the second event in 2016. We used this measurement to derive a mass of 0.150+0.062−0.051 (an error of ∼ 40\%) \MSun for Proxima Centauri acting as a lens. This is the first and the only currently possible measurement of the gravitational mass of Proxima Centauri.

This new value of the star's mass raises the msini mass of the planet from 1.27 to 1.56 times the mass of the Earth.

Technically, the 'gravitational mass' is the mass of the star plus the planet and everything else in the stellar system. However, Proxima Centauri is about 20,000 times the mass of its known planet, so that's a small correction at present.

Doesn’t this suppose that there aren’t other planets in the system, which at this time we can’t be sure that there aren’t?
Title: Re: Astronomy Thread
Post by: Dao Angkan on 07/05/2018 07:48 pm
The gravitational mass of Proxima Centauri measured with SPHERE from a microlensing event (https://arxiv.org/abs/1807.01318) (arXiv preprint)

Quote
(Abstract)
Proxima Centauri, our closest stellar neighbour, is a low-mass M5 dwarf orbiting in a triple system. An Earth-mass planet with an 11 day period has been discovered around this star. The star's mass has been estimated only indirectly using a mass-luminosity relation, meaning that large uncertainties affect our knowledge of its properties. To refine the mass estimate, an independent method has been proposed: gravitational microlensing. By taking advantage of the close passage of Proxima Cen in front of two background stars, it is possible to measure the astrometric shift caused by the microlensing effect due to these close encounters and estimate the gravitational mass of the lens (Proxima Cen). Microlensing events occurred in 2014 and 2016 with impact parameters, the closest approach of Proxima Cen to the background star, of 1\farcs6 ± 0\farcs1 and 0\farcs5 ± 0\farcs1, respectively. Accurate measurements of the positions of the background stars during the last two years have been obtained with HST/WFC3, and with VLT/SPHERE from the ground. The SPHERE campaign started on March 2015, and continued for more than two years, covering 9 epochs. The parameters of Proxima Centauri's motion on the sky, along with the pixel scale, true North, and centering of the instrument detector were readjusted for each epoch using the background stars visible in the IRDIS field of view. The experiment has been successful and the astrometric shift caused by the microlensing effect has been measured for the second event in 2016. We used this measurement to derive a mass of 0.150+0.062−0.051 (an error of ∼ 40\%) \MSun for Proxima Centauri acting as a lens. This is the first and the only currently possible measurement of the gravitational mass of Proxima Centauri.

This new value of the star's mass raises the msini mass of the planet from 1.27 to 1.56 times the mass of the Earth.

Technically, the 'gravitational mass' is the mass of the star plus the planet and everything else in the stellar system. However, Proxima Centauri is about 20,000 times the mass of its known planet, so that's a small correction at present.

Doesn’t this suppose that there aren’t other planets in the system, which at this time we can’t be sure that there aren’t?

I don't think so, this is just based on the period of the RV signal from Proxima b. If other planets are affecting Proxima b's RV signal, then that should be noticeable. So, if other planets are there, they are either misaligned with regards to Proxima b's orbit that it's RV can't currently be detected, or they are currently below the level of detection for an aligned orbit (either lower mass, but closer in, or possibly higher mass, but further out).

Edit: If transits are ruled out, then msini mass could be increased, especially for short period planets. So presuming that Proxima b doesn't transit, then that should lower the uncertainty about the inclination (and therefore mass) by a small amount.
Title: Re: Astronomy Thread
Post by: Alpha_Centauri on 07/05/2018 07:56 pm
Massive planets around Proxima have almost entirely been ruled out, and you wouldn't expect a massive planet around an M dwarf anyway.  Any other planets are likely roughly Proxima b sized or smaller.  So even if there are other planets they are not going to add significantly to the mass budget of the system.
Title: Re: Astronomy Thread
Post by: Dao Angkan on 07/05/2018 08:06 pm
Massive planets around Proxima have almost entirely been ruled out, and you wouldn't expect a massive planet around an M dwarf anyway.  Any other planets are likely roughly Proxima b sized or smaller.  So even if there are other planets they are not going to add significantly to the mass budget of the system.

As you say, we wouldn't expect to see massive planets around M dwarfs (although we might see "sub-brown dwarfs", which formed in the same way as binary stars via gravitational collapse). Still, if the planets' orbit is flat on to us (the opposite of a transit), then we can't detect it by RV. It would however be perfect for astrometry (GAIA), and possibly detectable through imaging techniques.
Title: Re: Astronomy Thread
Post by: Star One on 07/05/2018 08:08 pm
Massive planets around Proxima have almost entirely been ruled out, and you wouldn't expect a massive planet around an M dwarf anyway.  Any other planets are likely roughly Proxima b sized or smaller.  So even if there are other planets they are not going to add significantly to the mass budget of the system.

As you say, we wouldn't expect to see massive planets around M dwarfs (although we might see "sub-brown dwarfs", which formed in the same way as binary stars via gravitational collapse). Still, if the planets' orbit is flat on to us (the opposite of a transit), then we can't detect it by RV. It would however be perfect for astrometry (GAIA), and possibly detectable through imaging techniques.

When b was discovered wasn’t there a suggestion then of another planet?
Title: Re: Astronomy Thread
Post by: Dao Angkan on 07/05/2018 08:27 pm
Massive planets around Proxima have almost entirely been ruled out, and you wouldn't expect a massive planet around an M dwarf anyway.  Any other planets are likely roughly Proxima b sized or smaller.  So even if there are other planets they are not going to add significantly to the mass budget of the system.

As you say, we wouldn't expect to see massive planets around M dwarfs (although we might see "sub-brown dwarfs", which formed in the same way as binary stars via gravitational collapse). Still, if the planets' orbit is flat on to us (the opposite of a transit), then we can't detect it by RV. It would however be perfect for astrometry (GAIA), and possibly detectable through imaging techniques.

When b was discovered wasn’t there a suggestion then of another planet?

I think that there was a couple of potential longer period RV signals, but on far wider orbits. Lots of RV surveys in near-infrared targeting nearby M-dwarfs now, so hopefully we'll know of any more planets in the next few years. I think that this is a big question to answer, how common are single planet systems compared to multi-planet systems? My hunch is that single planet systems are rare, and that we currently see a lot of these due to observational bias, but it may well be that single planet systems really are common. I think that we'll get an answer to that question, at least around M-dwarfs within the next few years.
Title: Re: Astronomy Thread
Post by: Bynaus on 07/05/2018 09:36 pm
Note that the gravitational mass of Proxima given in the preprint has a comparatively large error of 40% (0.15 +-0.06/5)... This is a larger error than the luminosity-relation based value (0.12 +-0.02), and the two masses are compatible within their errors. Therefore, I'd argue that the luminosity-based value is to be preferred (the same is of course true for the mass of the planet).

If the mass of Proxima is larger, but the period of the planet and the luminosity of the star stay the same, then the planet must orbit further out, i.e. be colder than we thought. It was already a bit on the cold side, so this would affect habitability too.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 07/06/2018 07:41 am
Note that the gravitational mass of Proxima given in the preprint has a comparatively large error of 40% (0.15 +-0.06/5)... This is a larger error than the luminosity-relation based value (0.12 +-0.02), and the two masses are compatible within their errors. Therefore, I'd argue that the luminosity-based value is to be preferred (the same is of course true for the mass of the planet).

Is it possible to combine the two?
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 07/06/2018 07:59 am
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

Quote
(Abstract)
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈2 R⊕. Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii. Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%. We detect a clear bimodal distribution, with super-Earths (≈1.5 R⊕) and sub-Neptunes (≈2.5 R⊕) separated by a deficiency around 2 R⊕. We furthermore characterize the slope of the valley as a power law R∝Pγ with γ=−0.09+0.02−0.04. A negative slope is consistent with models of photo-evaporation, but not with the late formation of rocky planets in a gas-poor environment, which would lead to a slope of opposite sign. The exact location of the gap further points to planet cores consisting of a significant fraction of rocky material.

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.
Title: Re: Astronomy Thread
Post by: Star One on 07/07/2018 10:07 am
Fragment of impacting asteroid recovered in Botswana

Quote
On Saturday, June 23, 2018, a team of experts from Botswana, South Africa, Finland and the United States of America recovered a fresh meteorite in Botswana's Central Kalahari Game Reserve (CKGR). The meteorite is one of the fragments of asteroid 2018 LA which collided with Earth on June 2, 2018 and turned into a meteor fireball that detonated over Botswana a few seconds after entering the atmosphere. The incident was witnessed by a number of spectators in Botswana and neighbouring countries and was captured on numerous security cameras.

https://m.phys.org/news/2018-07-fragment-impacting-asteroid-recovered-botswana.html
Title: Re: Astronomy Thread
Post by: Star One on 07/10/2018 07:22 pm
Auroral hiss emissions during Cassini's Grand Finale: Diverse electrodynamic interactions between Saturn and its rings

Abstract

The Cassini Grand Finale orbits offered a new view of Saturn and its environment owing to multiple orbits of unprecedented proximity to the planet and high inclination. The Radio and Plasma Wave Science instrument detected striking signatures of plasma waves in the southern hemisphere. These all propagate in the whistler mode and are classified as: 1) A filled funnel‐shaped emission, commonly known as auroral hiss. Here however, our analysis indicates they are likely associated with currents connected to the rings. 2) First observations of VLF saucers directly linked to the planet on field lines also connected to the rings. The latter observations are unique to low altitude orbits and their presence at the Earth and Saturn alike show that they are fundamental plasma waves in planetary ionospheres. Our results give an insight, from a unique perspective, into the dynamic and diverse nature of Saturn's environment.

Plain Language Summary

Cassini's high‐inclination Grand Finale orbits brought the spacecraft closer to Saturn than ever before, with the closest approach between the cloud tops and the inner edge of the D ring. This unprecedented set of orbits introduced a new view of Saturn's system by enabling direct measurements of the topside ionosphere as well as the rings' surrounding environment. Here we present evidence of communication between Saturn's ionosphere and rings via plasma waves. These results underline Saturn's system as one of the most diverse and dynamic in the solar system.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL077875?campaign=wolacceptedarticle&
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/11/2018 05:18 am
Note that the gravitational mass of Proxima given in the preprint has a comparatively large error of 40% (0.15 +-0.06/5)... This is a larger error than the luminosity-relation based value (0.12 +-0.02), and the two masses are compatible within their errors. Therefore, I'd argue that the luminosity-based value is to be preferred (the same is of course true for the mass of the planet).

If the mass of Proxima is larger, but the period of the planet and the luminosity of the star stay the same, then the planet must orbit further out, i.e. be colder than we thought. It was already a bit on the cold side, so this would affect habitability too.
Not necessarily, Proxima b was on the warm side because the habitable-zone for M-dwarfs is placed at lower radiation flux. Even the stellar mass increases to 0.212 (the upper limit), the semi-major axis of b only moves out 0.1 au which results rather an insignificant change in radiation flux, placing the planet in the middle of habitable-zone.
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/11/2018 06:32 am
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

Quote
(Abstract)
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈2 R⊕. Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii. Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%. We detect a clear bimodal distribution, with super-Earths (≈1.5 R⊕) and sub-Neptunes (≈2.5 R⊕) separated by a deficiency around 2 R⊕. We furthermore characterize the slope of the valley as a power law R∝Pγ with γ=−0.09+0.02−0.04. A negative slope is consistent with models of photo-evaporation, but not with the late formation of rocky planets in a gas-poor environment, which would lead to a slope of opposite sign. The exact location of the gap further points to planet cores consisting of a significant fraction of rocky material.

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.
There is something different between Earth and super-Earths, and Neptune and sub-Neptunes. The ambiguity of these dictions lead people to think super-Earths are just the scaled up Earth and sub-Neptunes are just simply the scaled down Neptune with no clear compositional or formational distinctions, defining the boundary is just the matter of time.

In fact, they actually represent totally distinct planet populations which do not present in our solar system. Solar system planets can be compositionally categorized into three groups: rocky planets with little ice (<1%) and no gases (Mercury, Venus, Earth and Mars), gaseous (>80%) planets with little rocks and ice (Jupiter, Saturn), and icy (>50%) planets with little gases (<20%) and rocks (Neptune, Uranus).

Based on the location of the gap and atmospheric escape models, now we have a good reason to suspect that the majority of planets with radius under 1.6 (the so-called super-Earths) is actually rocky planets with >1% gases and no ice, but the atmospheres were blown away during later evolution. This population implies a formation process of rocky planets that is complete different from that of solar system rocky planets. Most planets with radius between 1.6 and 3 might share similar formation process (mainly rock with higher mass fraction of gases) with super-Earths but are enveloped by higher mass fraction of gases which could not be blown away. That is exactly why we need ARIEL to show us how alien these planets are.
Title: Astronomy Thread
Post by: Star One on 07/11/2018 03:24 pm
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

Quote
(Abstract)
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈2 R⊕. Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii. Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%. We detect a clear bimodal distribution, with super-Earths (≈1.5 R⊕) and sub-Neptunes (≈2.5 R⊕) separated by a deficiency around 2 R⊕. We furthermore characterize the slope of the valley as a power law R∝Pγ with γ=−0.09+0.02−0.04. A negative slope is consistent with models of photo-evaporation, but not with the late formation of rocky planets in a gas-poor environment, which would lead to a slope of opposite sign. The exact location of the gap further points to planet cores consisting of a significant fraction of rocky material.

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.
There is something different between Earth and super-Earths, and Neptune and sub-Neptunes. The ambiguity of these dictions lead people to think super-Earths are just the scaled up Earth and sub-Neptunes are just simply the scaled down Neptune with no clear compositional or formational distinctions, defining the boundary is just the matter of time.

In fact, they actually represent totally distinct planet populations which do not present in our solar system. Solar system planets can be compositionally categorized into three groups: rocky planets with little ice (<1%) and no gases (Mercury, Venus, Earth and Mars), gaseous (>80%) planets with little rocks and ice (Jupiter, Saturn), and icy (>50%) planets with little gases (<20%) and rocks (Neptune, Uranus).

Based on the location of the gap and atmospheric escape models, now we have a good reason to suspect that the majority of planets with radius under 1.6 (the so-called super-Earths) is actually rocky planets with >1% gases and no ice, but the atmospheres were blown away during later evolution. This population implies a formation process of rocky planets that is complete different from that of solar system rocky planets. Most planets with radius between 1.6 and 3 might share similar formation process (mainly rock with higher mass fraction of gases) with super-Earths but are enveloped by higher mass fraction of gases which could not be blown away. That is exactly why we need ARIEL to show us how alien these planets are.

Mike Brown & co would beg to differ with you on them not being represented in the Solar System as their theorised Planet Nine is a mini-Neptune.
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/12/2018 12:42 pm
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

Quote
(Abstract)
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈2 R⊕. Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii. Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%. We detect a clear bimodal distribution, with super-Earths (≈1.5 R⊕) and sub-Neptunes (≈2.5 R⊕) separated by a deficiency around 2 R⊕. We furthermore characterize the slope of the valley as a power law R∝Pγ with γ=−0.09+0.02−0.04. A negative slope is consistent with models of photo-evaporation, but not with the late formation of rocky planets in a gas-poor environment, which would lead to a slope of opposite sign. The exact location of the gap further points to planet cores consisting of a significant fraction of rocky material.

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.
There is something different between Earth and super-Earths, and Neptune and sub-Neptunes. The ambiguity of these dictions lead people to think super-Earths are just the scaled up Earth and sub-Neptunes are just simply the scaled down Neptune with no clear compositional or formational distinctions, defining the boundary is just the matter of time.

In fact, they actually represent totally distinct planet populations which do not present in our solar system. Solar system planets can be compositionally categorized into three groups: rocky planets with little ice (<1%) and no gases (Mercury, Venus, Earth and Mars), gaseous (>80%) planets with little rocks and ice (Jupiter, Saturn), and icy (>50%) planets with little gases (<20%) and rocks (Neptune, Uranus).

Based on the location of the gap and atmospheric escape models, now we have a good reason to suspect that the majority of planets with radius under 1.6 (the so-called super-Earths) is actually rocky planets with >1% gases and no ice, but the atmospheres were blown away during later evolution. This population implies a formation process of rocky planets that is complete different from that of solar system rocky planets. Most planets with radius between 1.6 and 3 might share similar formation process (mainly rock with higher mass fraction of gases) with super-Earths but are enveloped by higher mass fraction of gases which could not be blown away. That is exactly why we need ARIEL to show us how alien these planets are.

Mike Brown & co would beg to differ with you on them not being represented in the Solar System as their theorised Planet Nine is a mini-Neptune.
While mini-Neptunes observed around evaporation valley formed close-in with no ice, the putative Planet Nine would be composed of ice because it was assembled far away from the sun. Nevertheless, many super-Earths and sub-Neptunes detected in microlensing events are probably similar to Planet Nine.
Title: Re: Astronomy Thread
Post by: Star One on 07/12/2018 05:53 pm
Rare double asteroid revealed by NASA, Observatories

https://youtu.be/cbLqTfm_bac
Title: Re: Astronomy Thread
Post by: Star One on 07/12/2018 11:12 pm
Neutrino that struck Antarctica traced to galaxy 3.7bn light years away

Quote
A mysterious, ghostly particle that slammed into Earth and lit up sensors buried deep beneath the south pole has been traced back to a distant galaxy that harbours an enormous spinning black hole.

Astronomers detected the high-energy neutrino, a kind of subatomic particle, when it tore into the southern Indian Ocean near the coast of Antarctica and carried on until it struck an atomic nucleus in the Antarctic ice, sending more particles flying.

https://www.theguardian.com/science/2018/jul/12/neutrino-that-struck-antarctica-traced-to-galaxy-37bn-light-years-away
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 07/13/2018 01:14 am
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

[Snipped abstract]

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.

There is something different between Earth and super-Earths, and Neptune and sub-Neptunes. The ambiguity of these dictions lead people to think super-Earths are just the scaled up Earth and sub-Neptunes are just simply the scaled down Neptune with no clear compositional or formational distinctions, defining the boundary is just the matter of time.

In fact, they actually represent totally distinct planet populations which do not present in our solar system. Solar system planets can be compositionally categorized into three groups: rocky planets with little ice (<1%) and no gases (Mercury, Venus, Earth and Mars), gaseous (>80%) planets with little rocks and ice (Jupiter, Saturn), and icy (>50%) planets with little gases (<20%) and rocks (Neptune, Uranus).

Based on the location of the gap and atmospheric escape models, now we have a good reason to suspect that the majority of planets with radius under 1.6 (the so-called super-Earths) is actually rocky planets with >1% gases and no ice, but the atmospheres were blown away during later evolution. This population implies a formation process of rocky planets that is complete different from that of solar system rocky planets. Most planets with radius between 1.6 and 3 might share similar formation process (mainly rock with higher mass fraction of gases) with super-Earths but are enveloped by higher mass fraction of gases which could not be blown away. That is exactly why we need ARIEL to show us how alien these planets are.

Ah, the vagaries of astronomical terminology! :) It seemed to me (I could, of course, be under a misapprehension; but, that's how it seemed to me) that initially the term 'super-Earth' simply meant any planet with a mass bigger than Earth but less than Neptune and the term 'sub-Neptune' meant any planet with a mass less than Neptune but bigger than Earth. The overlap was obvious, but different astronomers preferred one or the other and as there was no scientific justification at the time to prefer one or the other both terms persisted. There was a tendency over time for some people to prefer 'super-Earth' for objects at the lower end of that mass range and 'sub-Neptune' for those at the upper, but nothing definitive until the demonstration of the Fulton or radius gap gave a clear(ish) boundary to hang such a distinction on. And that's where it seems to me the position is at present!

(One wrinkle is that people initially defined these terms with reference to the planet's mass (as given by radial velocity detections) but this is giving way to defining them with reference to the radius (as given by transit detections). There is some correlation of course, but both definitions seem to be persisting and should ideally be sorted out! Perhaps the use of r and m subscripts? :) )

I take your point about the different formation histories of the rocky planets of the solar system and those in the gap itself. Perhaps these should indeed be put into separate classes with (presumably!) the term super-Earth being reserved for the class which has the Earth as a member. And something similar for the term sub-Neptune? If so, this makes the mass or radius of the Earth and Neptune seem even more arbitrary as boundaries for these classes! What would be the real distinction between Venus, Earth and a super-Earth, etc?

My one caveat in having different classification classes for such objects based on their formation history is that although the distinction is clear conceptually, in practice how easy is it to determine the formation history of a particular object?
Title: Re: Astronomy Thread
Post by: Star One on 07/13/2018 07:45 pm
Bacterial survival in salty antifreeze raises hope for life on Mars and icy moons

Quote
New research by a trans-Atlantic team of scientists suggests that bacteria could survive in briny chemicals that exist on Mars, Enceladus, Europa, Pluto and possibly elsewhere.

https://www.astrobio.net/extreme-life/bacterial-survival-in-salty-antifreeze-raises-hope-for-life-on-mars-and-icy-moons/amp/
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/14/2018 08:15 am
An asteroseismic view of the radius valley: stripped cores, not born rocky (https://arxiv.org/abs/1710.05398) (arXiv accepted paper)

[Snipped abstract]

It seems that things have rapidly moved on from the question as to whether there is a 'Fulton gap' to questions about the characterisation of that gap! I also note that the gap itself is being used to clearly delineate super-Earths from sub-Neptunes. Previously it seemed that people used these as synonyms for exoplanets with sizes between Earth and Neptune.

Of course the use of Earth and Neptune in a classification scheme is, if not entirely arbitrary, somewhat anthropocentric. After all, there's no clear distinction between a super-Earth, Earth and, say, Venus, or between a sub-Neptune, Neptune and, say, Uranus. I suspect that sooner or later these terms will give way to classifications that span these objects and have the gap as their upper and lower bounds.

There is something different between Earth and super-Earths, and Neptune and sub-Neptunes. The ambiguity of these dictions lead people to think super-Earths are just the scaled up Earth and sub-Neptunes are just simply the scaled down Neptune with no clear compositional or formational distinctions, defining the boundary is just the matter of time.

In fact, they actually represent totally distinct planet populations which do not present in our solar system. Solar system planets can be compositionally categorized into three groups: rocky planets with little ice (<1%) and no gases (Mercury, Venus, Earth and Mars), gaseous (>80%) planets with little rocks and ice (Jupiter, Saturn), and icy (>50%) planets with little gases (<20%) and rocks (Neptune, Uranus).

Based on the location of the gap and atmospheric escape models, now we have a good reason to suspect that the majority of planets with radius under 1.6 (the so-called super-Earths) is actually rocky planets with >1% gases and no ice, but the atmospheres were blown away during later evolution. This population implies a formation process of rocky planets that is complete different from that of solar system rocky planets. Most planets with radius between 1.6 and 3 might share similar formation process (mainly rock with higher mass fraction of gases) with super-Earths but are enveloped by higher mass fraction of gases which could not be blown away. That is exactly why we need ARIEL to show us how alien these planets are.

Ah, the vagaries of astronomical terminology! :) It seemed to me (I could, of course, be under a misapprehension; but, that's how it seemed to me) that initially the term 'super-Earth' simply meant any planet with a mass bigger than Earth but less than Neptune and the term 'sub-Neptune' meant any planet with a mass less than Neptune but bigger than Earth. The overlap was obvious, but different astronomers preferred one or the other and as there was no scientific justification at the time to prefer one or the other both terms persisted. There was a tendency over time for some people to prefer 'super-Earth' for objects at the lower end of that mass range and 'sub-Neptune' for those at the upper, but nothing definitive until the demonstration of the Fulton or radius gap gave a clear(ish) boundary to hang such a distinction on. And that's where it seems to me the position is at present!

(One wrinkle is that people initially defined these terms with reference to the planet's mass (as given by radial velocity detections) but this is giving way to defining them with reference to the radius (as given by transit detections). There is some correlation of course, but both definitions seem to be persisting and should ideally be sorted out! Perhaps the use of r and m subscripts? :) )

I take your point about the different formation histories of the rocky planets of the solar system and those in the gap itself. Perhaps these should indeed be put into separate classes with (presumably!) the term super-Earth being reserved for the class which has the Earth as a member. And something similar for the term sub-Neptune? If so, this makes the mass or radius of the Earth and Neptune seem even more arbitrary as boundaries for these classes! What would be the real distinction between Venus, Earth and a super-Earth, etc?

My one caveat in having different classification classes for such objects based on their formation history is that although the distinction is clear conceptually, in practice how easy is it to determine the formation history of a particular object?
Complete understandable, some scientists have already begin to change the astronomical language and terms, like this one https://doi.org/10.1038/s41550-017-0042
Title: Re: Astronomy Thread
Post by: eeergo on 07/14/2018 10:21 am
MeerKAT radio telescope inaugurated in South Africa – reveals clearest view yet of centre of the Milky Way


http://www.ska.ac.za/media-releases/meerkat-radio-telescope-inaugurated-in-south-africa-reveals-clearest-view-yet-of-center-of-the-milky-way/
Title: Astronomy Thread
Post by: Star One on 07/14/2018 10:38 am
Could those filaments be “cosmic strings” caught in the gravity well of the SMB?
Title: Re: Astronomy Thread
Post by: eeergo on 07/14/2018 01:26 pm
These filaments have been known since the 90s, and there's still debate about what causes them, but the current consensus seems to point toward magnetically-stabilized (rather than gravitationally) dust:

http://www.astronomy.com/news/2018/02/milky-way-core-revealed-in-clearest-infrared-image-yet (http://www.astronomy.com/news/2018/02/milky-way-core-revealed-in-clearest-infrared-image-yet) (February)
https://gizmodo.com/new-south-african-telescope-releases-epic-image-of-the-1827572028 (https://gizmodo.com/new-south-african-telescope-releases-epic-image-of-the-1827572028) (July)
https://www.nrao.edu/pr/2004/filaments/ (https://www.nrao.edu/pr/2004/filaments/) (2004)
https://link.springer.com/chapter/10.1007/978-94-009-1687-6_31 (https://link.springer.com/chapter/10.1007/978-94-009-1687-6_31) (1996)
Title: Re: Astronomy Thread
Post by: Star One on 07/16/2018 06:56 am
The Hunt for Earth’s Deep Hidden Oceans

Quote
According to the standard tale, Earth’s water was imported. The region around the sun where the planet formed was too hot for volatile compounds like water to condense. So the nascent Earth started out dry, getting wet only after water-rich bodies from the distant solar system crashed into the planet, delivering water to the surface. Most of these were likely not comets but rather asteroids called carbonaceous chondrites, which can be up to 20 percent water by weight, storing it in a form of hydrogen like ringwoodite.

But if there’s a huge stockpile of water in the transition zone, this story of water’s origin would have to change. If the transition zone could store 1 percent of its weight in water — a moderate estimate, Jacobsen said — it would contain twice the world’s oceans. The lower mantle is much drier but also voluminous. It could amount to all the world’s oceans (again). There’s water in the crust, too. For subduction to incorporate that much water from the surface at the current rate, it would take much longer than the age of the planet, Jacobsen said.

https://www.quantamagazine.org/the-hunt-for-earths-deep-hidden-oceans-20180711/
Title: Re: Astronomy Thread
Post by: Star One on 07/17/2018 03:46 pm
12 New Moons of Jupiter Discovered

Quote
It may come as a surprise, then, that astronomers still find new moons orbiting the largest planet in the solar system. But 12 more moons were just discovered, bringing the total to 79, the most of any planet that orbits the sun. These small moons were not discovered by a spacecraft, but rather by powerful telescopes on Earth—and by a team, led by Carnegie Institution for Science astronomer Scott Sheppard, that didn't even set out to look for them.

"These moons are the last remnants of the objects that the planets were built from," Sheppard tells Popular Mechanics via email. "Most of the small objects that helped build the planets we see today were incorporated into the planets themselves, and these moons are all that remains."

https://www.popularmechanics.com/space/a22185640/dozen-new-moons-discovered-jupiter/

Title: Re: Astronomy Thread
Post by: Star One on 07/17/2018 08:26 pm
The Hawaii Infrared Parallax Program. III. 2MASS J0249-0557 c: A Wide Planetary-mass Companion to a Low-mass Binary in the beta Pic Moving Group

We have discovered a wide planetary-mass companion to the β Pic moving group member 2MASSJ02495639-0557352 (M6 VL-G) using CFHT/WIRCam astrometry from the Hawaii Infrared Parallax Program. In addition, Keck laser guide star adaptive optics aperture-masking interferometry shows that the host is itself a tight binary. Altogether, 2MASSJ0249-0557ABc is a bound triple system with an 11.6+1.0−1.3 MJup object separated by 1950±200 AU (40") from a relatively close (2.17±0.22 AU, 0.04") pair of 48+12−13 MJup and 44+11−14 MJup objects. 2MASSJ0249-0557AB is one of the few ultracool binaries to be discovered in a young moving group and the first confirmed in the β Pic moving group (22±6 Myr). The mass, absolute magnitudes, and spectral type of 2MASSJ0249-0557 c (L2 VL-G) are remarkably similar to those of the planet β Pic b (L2, 13.0+0.4−0.3 MJup). We also find that the free-floating object 2MASSJ2208+2921 (L3 VL-G) is another possible β Pic moving group member with colors and absolute magnitudes similar to β Pic b and 2MASSJ0249-0557 c. β Pic b is the first directly imaged planet to have a "twin," namely an object of comparable properties in the same stellar association. Such directly imaged objects provide a unique opportunity to measure atmospheric composition, variability, and rotation across different pathways of assembling planetary-mass objects from the same natal material.

https://arxiv.org/abs/1807.05235
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/19/2018 04:41 am
A new planet transiting LHS 1140 is discovered with an orbital period 3.8 day. The real properties like radius are yet to be published. I will do some calculation to show a possible radius and compositional range of this planet.
A 3.8 day planet signal with less than 3 Earth-mass is also discovered in radial velocity date after reanalyzing the Dittmann et al's work.
Transmission spectroscopy study revises the LHS 1140 b radius to 1.63 Earth-radius.
Title: Re: Astronomy Thread
Post by: ExoExplorer on 07/19/2018 06:47 am
Just did a little calculation with the transit depth of LHS-1140c in the graph.

There are three sources of LHS-1140 radius available: 0.186±0.013 Rs (original study), ~0.2 Rs (new transmission spectroscopy), and 0.223±0.013 Rs (Gaia DR2).

planet radius (in Earth unit) = Transit depth^0.5 * stellar radius / Earth radius

According to the graph, I am pretty confident that the relative flux of LHS-1140 drops to ~0.997 when planet c transits, so the transit depth is 0.003.

Take 0.19 Rs (new transmission spectroscopy) and 0.23 Rs (Gaia DR2) as stellar radius lower limit and upper limit, I get 1.25±0.12 Rp for the radius of planet c.

The additional radial velocity of c is presented in arxiv.org/abs/1807.02483, showing that the mass likely falls somewhere in between 1.5 and 2 Earth-mass.
Therefore, the bulk density of c would be 5.4±2.2g/cm3.

Its composition lies between oceanworld and rocky planet (including Earth-like composition). Unless we can further constrain the planetary mass and radius, there is no a sure conclusion to its volatile inventory.

The short orbital distance makes this planet extremely hot and uninhabitable, contrasting to its neighbor b.
Title: Re: Astronomy Thread
Post by: Star One on 07/19/2018 01:32 pm
Wandering Star May Have Disrupted Outer Solar System's Order

Quote
There's something strange about the outer solar system — and that could be the signature of a long-ago visit to our neighborhood, according to a new study that looked to simulate how the outer solar system might have ended up so oddly arranged.

https://www.space.com/41212-wandering-star-disturbed-outer-solar-system.html
Title: Re: Astronomy Thread
Post by: Star One on 07/19/2018 02:04 pm
Supersharp Images from New VLT Adaptive Optics

ESO’s Very Large Telescope (VLT) has achieved first light with a new adaptive optics mode called laser tomography — and has captured remarkably sharp test images of the planet Neptune, star clusters and other objects. The pioneering MUSE instrument in Narrow-Field Mode, working with the GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere. It is now possible to capture images from the ground at visible wavelengths that are sharper than those from the NASA/ESA Hubble Space Telescope. The combination of exquisite image sharpness and the spectroscopic capabilities of MUSE will enable astronomers to study the properties of astronomical objects in much greater detail than was possible before.

The MUSE (Multi Unit Spectroscopic Explorer) instrument on ESO’s Very Large Telescope (VLT) works with an adaptive optics unit called GALACSI. This makes use of the Laser Guide Star Facility, 4LGSF, a subsystem of the Adaptive Optics Facility (AOF). The AOF provides adaptive optics for instruments on the VLTs Unit Telescope 4 (UT4). MUSE was the first instrument to benefit from this new facility and it now has two adaptive optics modes — the Wide Field Mode and the Narrow Field Mode [1].

The MUSE Wide Field Mode coupled to GALACSI in ground-layer mode corrects for the effects of atmospheric turbulence up to one kilometre above the telescope over a comparatively wide field of view. But the new Narrow Field Mode using laser tomography corrects for almost all of the atmospheric turbulence above the telescope to create much sharper images, but over a smaller region of the sky [2].

With this new capability, the 8-metre UT4 reaches the theoretical limit of image sharpness and is no longer limited by atmospheric blur. This is extremely difficult to attain in the visible and gives images comparable in sharpness to those from the NASA/ESA Hubble Space Telescope. It will enable astronomers to study in unprecedented detail fascinating objects such as supermassive black holes at the centres of distant galaxies, jets from young stars, globular clusters, supernovae, planets and their satellites in the Solar System and much more.

Adaptive optics is a technique to compensate for the blurring effect of the Earth’s atmosphere, also known as astronomical seeing, which is a big problem faced by all ground-based telescopes. The same turbulence in the atmosphere that causes stars to twinkle to the naked eye results in blurred images of the Universe for large telescopes. Light from stars and galaxies becomes distorted as it passes through our atmosphere, and astronomers must use clever technology to improve image quality artificially.

To achieve this four brilliant lasers are fixed to UT4 that project columns of intense orange light 30 centimetres in diameter into the sky, stimulating sodium atoms high in the atmosphere and creating artificial Laser Guide Stars. Adaptive optics systems use the light from these “stars” to determine the turbulence in the atmosphere and calculate corrections one thousand times per second, commanding the thin, deformable secondary mirror of UT4 to constantly alter its shape, correcting for the distorted light.

MUSE is not the only instrument to benefit from the Adaptive Optics Facility. Another adaptive optics system, GRAAL, is already in use with the infrared camera HAWK-I. This will be followed in a few years by the powerful new instrument ERIS. Together these major developments in adaptive optics are enhancing the already powerful fleet of ESO telescopes, bringing the Universe into focus.

This new mode also constitutes a major step forward for the ESO’s Extremely Large Telescope, which will need Laser Tomography to reach its science goals. These results on UT4 with the AOF will help to bring ELT’s engineers and scientists closer to implementing similar adaptive optics technology on the 39-metre giant.

https://www.eso.org/public/news/eso1824/

Here’s a video as well.

https://youtu.be/yDMV7kmrfWY

Title: Re: Astronomy Thread
Post by: Star One on 07/20/2018 07:55 pm
How Disc Galaxies Work

Quote
Disc galaxies like our own Milky Way, characterized by a flattened disc of stars and gas (often with a central bulge of material as well) have a wide range of masses, spatial extents, and stellar content. Nonetheless all disc galaxies, both locally and in the distant Universe, share some strikingly similar properties. Most notable is that the star formation rate correlates tightly with the galaxy’s gas content, the gas motions (the "velocity dispersion"), and the dynamical lifetime (roughly, the time it takes for the galaxy to rotate once). Moreover, this curiously universal rate is remarkably small: only about one per cent of the gas in disc galaxies turns into stars over that timescale, with much of the activity concentrated in the galaxies’ central regions. Most simple models of star formation predict that gravity should be much more effective in forming stars as it compresses the gas in molecular clouds. Observations indicate that both the correlations and the inefficiency extend down to the scale of individual molecular clouds.

https://www.cfa.harvard.edu/news/su201829
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 07/22/2018 02:07 am
The first super-Earth Detection from the High Cadence and High Radial Velocity Precision Dharma Planet Survey (https://arxiv.org/pdf/1807.07098.pdf) (arXiv pdf)

Quote
(Abstract)
The Dharma Planet Survey (DPS) aims to monitor about 150 nearby very bright FGKM dwarfs (within 50 pc) during 2016−2020 for low-mass planet detection and characterization using the TOU very high resolution optical spectrograph (R≈100,000, 380-900nm). TOU was initially mounted to the 2-m Automatic Spectroscopic Telescope at Fairborn Observatory in 2013-2015 to conduct a pilot survey, then moved to the dedicated 50-inch automatic telescope on Mt. Lemmon in 2016 to launch the survey. Here we report the first planet detection from DPS, a super-Earth candidate orbiting a bright K dwarf star, HD 26965. It is the second brightest star (V = 4.4 mag) on the sky with a super-Earth candidate. The planet candidate has a mass of 8.47±0.47MEarth, period of 42.38 ± 0.01 d, and eccentricity of 0.04+0.05−0.03. This RV signal was independently detected by Diaz et al. (2018), but they could not confirm if the signal is from a planet or from stellar activity. The orbital period of the planet is close to the rotation period of the star (39−44.5 d) measured from stellar activity indicators. Our high precision photometric campaign and line bisector analysis of this star do not find any significant variations at the orbital period. Stellar RV jitters modeled from star spots and convection inhibition are also not strong enough to explain the RV signal detected. After further comparing RV data from the star’s active magnetic phase and quiet magnetic phase, we conclude that the RV signal is due to planetary-reflex motion and not stellar activity.

HD 26965 is the star named Keid, the primary or A component of the 40 Eridani triple star system (and the host star of the planet Vulcan in Star Trek). I know that (for good reasons) astronomers prefer to use modern catalogue designations to identify stars rather than proper names or old designations such as the Flamsteed designation 40 Eridani. However, if they're concerned to leverage popular interest in astronomy they should give some thought to including such alternate designations or names to attract the attention of said populace, or at least of journalists - it only takes a sentence!

It's interesting how automatic telescopes are enabling more frequent radial-velocity observations improving detection of exoplanets:

Quote
Every target will be initially observed ∼30 consecutive observable nights to target close-in low-mass planets detection. After that, each target will be observed an additional ∼70 times randomly spread over 420 days. The automatic nature of the 50-inch telescope and its flexible queue observation schedule are key to realizing this nearly homogenous high cadence.

I also note they used R-V observations from Keck/HIRES, HARPS, PFS and CHIRON, a good example of how science is cumulative.

As a bit of an astronomical terminology buff, I note they called this a super-Earth. This is despite noting that it "likely possesses a gaseous atmosphere". At a minimum mass of 8.47 times Earth, it will have a radius of over twice that of Earth if of the same average density and an even bigger radius with a gaseous atmosphere (which I take to mean a large gaseous envelope as all atmospheres are gaseous!) as that would reduce the average density. That puts it on the upper edge if not over the so-called Fulton or radius gap. Given that the mass is likely above the minimum, I think this planet is better described as a sub-Neptune!
Title: Astronomy Thread
Post by: Star One on 07/23/2018 07:45 pm
Preservation of potential biosignatures in the shallow subsurface of Europa

Jupiter’s moon Europa, which is thought to possess a large liquid water ocean beneath its icy crust, is one of the most compelling targets in the search for life beyond Earth. Its geologically young surface, along with a number of surface features, indicate that material from Europa’s interior may be emplaced on the surface. However, the surface is affected by the harsh radiation environment of Jupiter’s magnetosphere, which over time may lead to chemical alteration and destruction of potential biosignatures. We show that radiation dose rates are highly dependent on surface location. Radiation processing and destruction of potential biosignatures is found to be significant down to depths of ~1 cm in mid- to high-latitude regions, and to depths of 10–20 cm within ‘radiation lenses’ centred on the leading and trailing hemispheres. These results indicate that future missions to Europa’s surface do not need to excavate material to great depths to investigate the composition of endogenic material and search for potential biosignatures.

https://www.nature.com/articles/s41550-018-0499-8

NASA Press Release

Radiation Maps of Jupiter's Moon Europa: Key to Future Missions

https://www.jpl.nasa.gov/news/news.php?release=2018-170&rn=news.xml&rst=7191
Title: Re: Astronomy Thread
Post by: Star One on 07/23/2018 08:17 pm
Storm Chasers' on Mars Searching for Dusty Secrets

Storm chasing takes luck and patience on Earth -- and even more so on Mars.

For scientists watching the Red Planet from data gathered by NASA's orbiters, the past month has been a windfall. "Global" dust storms, where a runaway series of storms creates a dust cloud so large it envelops the planet, only appear every six to eight years (that's three to four Mars years). Scientists still don't understand why or how exactly these storms form and evolve.

https://youtu.be/JcMpO4Tn0UE

In June, one of these dust events rapidly engulfed the planet. Scientists first observed a smaller-scale dust storm on May 30. By June 20, it had gone global.

For the Opportunity rover, that meant a sudden drop in visibility from a clear, sunny day to that of an overcast one. Because Opportunity runs on solar energy, scientists had to suspend science activities to preserve the rover's batteries. As of July 18th, no response has been received from the rover.

Luckily, all that dust acts as an atmospheric insulator, keeping nighttime temperatures from dropping down to lower than what Opportunity can handle. But the nearly 15-year-old rover isn't out of the woods yet: it could take weeks, or even months, for the dust to start settling. Based on the longevity of a 2001 global storm, NASA scientists estimate it may be early September before the haze has cleared enough for Opportunity to power up and call home.

When the skies begin to clear, Opportunity's solar panels may be covered by a fine film of dust. That could delay a recovery of the rover as it gathers energy to recharge its batteries. A gust of wind would help, but isn't a requirement for a full recovery..

While the Opportunity team waits in earnest to hear from the rover, scientists on other Mars missions have gotten a rare chance to study this head-scratching phenomenon.

The Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiters are all tailoring their observations of the Red Planet to study this global storm and learn more about Mars' weather patterns. Meanwhile, the Curiosity rover is studying the dust storm from the Martian surface.

Here's Here's how each mission is currently studying the dust storm, and what we might learn from it:


Mars Odyssey

With the THEMIS instrument (Thermal Emission Imaging System), scientists can track Mars' surface temperature, atmospheric temperature, and the amount of dust in the atmosphere. This allows them to watch the dust storm grow, evolve, and dissipate over time.

"This is one of the largest weather events that we've seen on Mars," since spacecraft observations began in the 1960s, said Michael Smith, a scientist at NASA's Goddard Spaceflight Center in Greenbelt, Maryland who works on the THEMIS instrument. "Having another example of a dust storm really helps us to understand what's going on."

Since the dust storm began, the THEMIS team has increased the frequency of global atmospheric observations from every 10 days to twice per week, Smith said. One mystery they're still trying to solve: How these dust storms go global. "Every Mars year, during the dusty season, there are a lot of local- or regional-scale storms that cover one area of the planet," Smith said. But scientists aren't yet sure how these smaller storms sometimes grow to end up encircling the entire planet.

Mars Reconnaissance Orbiter (MRO)

Mars Reconnaissance Orbiter has two instruments studying the dust storm. Each day, the Mars Color Imager (MARCI) maps the entire planet in mid-afternoon to track the evolution of the storm. Meanwhile, MRO's Mars Climate Sounder (MCS) instrument measures how the atmosphere's temperature changes with altitude. Since the end of May, the instruments have observed the onset and rapid expansion of a dust storm on Mars.

With these data, scientists are studying how the dust storm changes the planet's atmospheric temperatures. Just as in Earth's atmosphere, changing temperature on Mars can affect wind patterns and even the circulation of the entire atmosphere. This provides a powerful feedback: Solar heating of the dust lofted into the atmosphere changes temperatures, which changes winds, which may amplify the storm by lifting more dust from the surface.

Scientists want to know the details of the storm -- where is the air rising or falling? How do the atmospheric temperatures now compare to a storm-less year? And as with Mars Odyssey, the MRO team wants to know how these dust storms go global.

"The very fact that you can start with something that's a local storm, no bigger than a small [U.S.] state, and then trigger something that raises more dust and produces a haze that covers almost the entire planet is remarkable," said Rich Zurek of NASA's Jet Propulsion Laboratory, Pasadena, California, the project scientist for MRO.

Scientists want to find out why these storms arise every few years, which is hard to do without a long record of such events. It'd be as if aliens were observing Earth and seeing the climate effects of El Niño over many years of observations -- they'd wonder why some regions get extra rainy and some areas get extra dry in a seemingly regular pattern.

MAVEN

Ever since the MAVEN orbiter entered Mars' orbit, "one of the things we've been waiting for is a global dust storm," said Bruce Jakosky, the MAVEN orbiter's principle investigator.

But MAVEN isn't studying the dust storm itself. Rather, the MAVEN team wants to study how the dust storm affects Mars' upper atmosphere, about 62 miles (more than 100 kilometers) above the surface -- where the dust doesn't even reach. MAVEN's mission is to figure out what happened to Mars' early atmosphere. We know that at some point billions of years ago, liquid water pooled and ran along Mars' surface, which means that its atmosphere must have been thicker and more insulating, similar to Earth's. Since MAVEN arrived at Mars in 2014, its investigations have found that this atmosphere may have been stripped away by a torrent of solar wind over several hundred million years, between 3.5 and 4.0 billion years ago.

But there are still nuances to figure out, such as how dust storms like the current one affect how atmospheric molecules escape into space, Jakosky said. For instance, the dust storm acts as an atmospheric insulator, trapping heat from the Sun. Does this heating change the way molecules escape the atmosphere? It is also likely that, as the atmosphere warms, more water vapor rises high enough to be broken down by sunlight, with the solar wind sweeping the hydrogen atoms into space, Jakosky said.

The team won't have answers for a while yet, but each of MAVEN's five orbits per day will continue to provide invaluable data.

Curiosity

Most of NASA's spacecraft are studying the dust storm from above. The Mars Science Laboratory mission's Curiosity rover has a unique perspective: the nuclear-powered science machine is largely immune to the darkened skies, allowing it to collect science from within the beige veil enveloping the planet.

"We're working double-duty right now," said JPL's Ashwin Vasavada, Curiosity's project scientist. "Our newly recommissioned drill is acquiring a fresh rock sample. But we are also using instruments to study how the dust storm evolves."

Curiosity has a number of "eyes" that can determine the abundance and size of dust particles based on how they scatter and absorb light. That includes its Mastcam, ChemCam, and an ultraviolet sensor on REMS, its suite of weather instruments. REMS can also help study atmospheric tides -- shifts in pressure that move as waves across the entire planet's thin air. These tides change drastically based on where the dust is globally, not just inside Gale crater.

The global storm may also reveal secrets about Martian dust devils and winds. Dust devils can occur when the planet's surface is hotter than the air above it. Heating generates whirls of air, some of which pick up dust and become dust devils. During a dust storm, there's less direct sunlight and lower daytime temperatures; this might mean fewer devils swirling across the surface.

Even new drilling can advance dust storm science: watching the small piles of loose material created by Curiosity's drill is the best way of monitoring winds.

Scientists think the dust storm will last at least a couple of months. Every time you spot Mars in the sky in the weeks ahead, remember how much data scientists are gathering to better understand the mysterious weather of the Red Planet.


Title: Astronomy Thread
Post by: Star One on 07/23/2018 08:29 pm
NASA Launches X-ray Telescope on Sounding Rocket to Study Star Wreckage

Editor's note, July 23, 2018: The Micro-X team reports that while the detector functioned as expected during the flight, demonstrating the technology in space flight for the first time, the observatory’s pointing system was unable to lock onto its target, Cassiopeia A. The team will be looking forward to its next opportunity for a reflight.

NASA launched a prototype telescope and instrument to observe the X-rays emitted by Cassiopeia A, the expanding debris of an exploded star. The High-Resolution Microcalorimeter X-ray Imaging Rocket (Micro-X) launched July 22 aboard a sub-orbital launch vehicle called a sounding rocket and successfully tested its detector technology. 

“The flight time of a sounding rocket is short compared to orbiting satellites, so you have to get as much light as you can to do the science you want,” said Principal Investigator Enectali Figueroa-Feliciano, an associate professor of physics at Northwestern University in Evanston, Illinois. “There are only a couple of X-ray sources in the sky that are bright enough for the few minutes of observation time such flights give us, and Cassiopeia A is one of the brightest. Our study will build on the current knowledge of supernova remnants, how they exploded and evolve, and we will get new insights into the history of Cassiopeia A.”

Launched from the U.S. Army’s White Sands Missile Range in New Mexico, Micro-X soared to an altitude of 100 miles (160 kilometers) — required to detect X-rays that are absorbed by Earth’s atmosphere — and observed the remnant for the next five minutes. At its pinnacle Micro-X reached an altitude of 167 miles (270 kilometers).

The mission incorporates the first array of transition-edge sensor X-ray microcalorimeters to fly into space. These sensors act as highly sensitive thermometers and make ideal detectors for an X-ray telescope.

The microcalorimeter is comprised of three main parts: an absorber which takes in light and converts it to heat, a thermistor that alters its own resistance due to changing temperature and a heat sink that cools the microcalorimeter back down.

For Micro-X, a refrigerator cools the detector to about 459 degrees below zero Fahrenheit (0.075 degree Celsius above absolute zero), or nearly the minimum temperature possible. When the instrument detects X-rays, the light’s energy is converted into heat. This causes a slight rise in temperature, prompting the refrigerator to cool the detector back to its original temperature. The energy of each X-ray can be determined from the change in temperature.

One of the many questions that scientists are interested in using the data to answer is whether or not the temperatures of the gases ejected from the star’s explosion are the same for iron and silicon, two elements which were previously measured by NASA’s Chandra X-ray Observatory. Such an analysis was not possible with Chandra’s spectrometers.

“With Chandra, different regions of the supernova remnant overlap in the spectrometer,” said F. Scott Porter, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is participating in the mission. “Micro-X is different because it can take every single photon in its field of view, tell the exact energy and make a spectrum.”

The information collected by Micro-X will also be used to help answer the question of how much oxygen resides in Cassiopeia A, create a survey of the various other elements in the remnant and measure the speed of the ring-like ejecta from the exploded star.

One aspect of research that was not possible before Micro-X was the measurement of weak spectral lines. These observations will now tell scientists which gases are present as well as their speed and direction. This is possible because light from sources moving toward or away from us causes a shift in wavelength depending on their speed, a phenomenon known as the Doppler shift.

Both the mission of Micro-X and the utilization of transition-edge sensors will continue in the future. The Micro-X team plans to direct their attention to other cosmic objects. “In future flights we can look at other sources like other supernova remnants or clusters of galaxies,” said Figueroa-Feliciano. “We have even thought about using this type of rocket to look for dark matter.”

Transition-edge sensors will also be incorporated in upcoming orbital missions. ESA’s (European Space Agency) Advanced Telescope for High Energy Astrophysics (ATHENA), planned for launch in the early 2030s, will wield an array of about 5,000 pixels, nearly 40 times the size of Micro-X’s 128-pixel detector. ATHENA will study hot gas structures — such as groups of galaxies — and conduct a census of black holes.

In addition to NASA and Northwestern University, Micro-X is supported by the National Institute of Standards and Technology in Boulder, Colorado, the Massachusetts Institute of Technology in Cambridge, Massachusetts, and the University of Wisconsin-Madison.

NASA's Sounding Rocket Program is conducted at the agency's Wallops Flight Facility at Wallops Island, Virginia, which is managed by Goddard. NASA's Heliophysics Division manages the sounding rocket program for the agency. The development of the Micro-X payload was supported by NASA’s Astrophysics Division.

https://www.nasa.gov/feature/goddard/2018/nasa-launches-x-ray-telescope-on-sounding-rocket-to-study-star-wreckage
Title: Astronomy Thread
Post by: Star One on 07/26/2018 04:10 pm
First successful test of Einstein’s General Relativity near a Super Massive Black Hole

https://www.youtube.com/watch?v=if2opecmev8
Title: Re: Astronomy Thread
Post by: Star One on 07/27/2018 08:44 pm
Black holes really just ever-growing balls of string, researchers say

Quote
Black holes aren’t surrounded by a burning ring of fire after all, suggests new research.

Some physicists have believed in a “firewall” around the perimeter of a black hole that would incinerate anything sucked into its powerful gravitational pull.

But a team from The Ohio State University has calculated an explanation of what would happen if an electron fell into a typical black hole, with a mass as big as the sun.

https://news.osu.edu/black-holes-really-just-ever-growing-balls-of-string-researchers-say/
Title: Re: Astronomy Thread
Post by: Star One on 07/30/2018 08:43 pm
Blueberry Earth

Quote
This paper explores the physics of the what-if question "what if the entire Earth was instantaneously replaced with an equal volume of closely packed, but uncompressed blueberries?" While the assumption may be absurd, the consequences can be explored rigorously using elementary physics. The result is not entirely dissimilar to a small ocean-world exoplanet.

https://arxiv.org/abs/1807.10553
Title: Astronomy Thread
Post by: Star One on 08/01/2018 06:47 am
Ancient space crystals may prove the sun threw heated tantrums as a tot

Quote
It’s natural to assume even our 4.6 billion-year-old sun had a messy heyday in its youth, but without any hard evidence to prove this was case, the only thing many scientists had going for them were strong suspicions. New data, focused around a peculiar set of ancient blue crystals from space, seems to suggest the sun emitted a much higher flux of cosmic rays in its early history than we once thought.
Those blue crystals are called hibonite, and they’ve arrived here on Earth by way of meteorite impacts. Hibonite are effectively some of the first minerals formed in the solar system, created by the cooling gas derived from the sun. The new study, published in Nature Astronomy, focuses on the Murchison meteorite, which fell in Australia in 1969, likely originating from an asteroid in the asteroid belt—and which possesses pieces of micron barely larger than the width of human hair.

https://www.popsci.com/space-crystal-meteorite-early-sun

Plate tectonics not needed to sustain life

Quote
There may be more habitable planets in the universe than we previously thought, according to Penn State geoscientists, who suggest that plate tectonics—long assumed to be a requirement for suitable conditions for life—are in fact not necessary.

https://phys.org/news/2018-07-plate-tectonics-sustain-life.amp?
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 08/01/2018 06:50 am
Revised Radii of Kepler Stars and Planets using Gaia Data Release 2 (https://arxiv.org/abs/1805.00231) (arXiv)

Quote
(Abstract)
One bottleneck for the exploitation of data from the Kepler mission for stellar astrophysics and exoplanet research has been the lack of precise radii and evolutionary states for most of the observed stars. We report revised radii of 177,911 Kepler stars derived by combining parallaxes from Gaia Data Release 2 with the DR25 Kepler Stellar Properties Catalog. The median radius precision is ≈ 8%, a typical improvement by a factor of 4-5 over previous estimates for typical Kepler stars. We find that ≈ 67% (≈ 120,000) of all Kepler targets are main-sequence stars, ≈ 21% (≈ 37,000) are subgiants, and ≈ 12% (≈ 21,000) are red giants, demonstrating that subgiant contamination is less severe than some previous estimates and that Kepler targets are mostly main-sequence stars. Using the revised stellar radii, we recalculate the radii for 2123 confirmed and 1922 candidate exoplanets. We confirm the presence of a gap in the radius distribution of small, close-in planets, but find that the gap is mostly limited to incident fluxes > 200F⊕ and its location may be at a slightly larger radius (closer to ≈ 2R⊕) when compared to previous results. Further, we find several confirmed exoplanets occupying a previously-described "hot super-Earth desert" at high irradiance, show the relation between gas-giant planet radius and incident flux, and establish a bona-fide sample of eight confirmed planets and 30 planet candidates with Rp < 2R⊕ in circumstellar "habitable zones" (incident fluxes between 0.25--1.50 F⊕). The results presented here demonstrate the potential for transformative characterization of stellar and exoplanet populations using Gaia data.
Title: Re: Astronomy Thread
Post by: Star One on 08/01/2018 08:11 pm
New radio telescope picks up mysterious signal from space

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The observatory in Canada may have already found clues to one of the newest mysteries in astronomy.

https://www.cnet.com/google-amp/news/new-radio-telescope-picks-up-mysterious-signal-from-space/
Title: Re: Astronomy Thread
Post by: Star One on 08/03/2018 08:25 pm
New facility to simulate conditions on Venus

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The German Space Agency (DLR) has opened a new simulation facility at its Planetary Spectroscopy Laboratory (PSL) in Berlin. The facility could help researchers better understand the surface of Venus hidden behind the planet's dense atmosphere.

https://phys.org/news/2018-08-facility-simulate-conditions-venus.amp (https://phys.org/news/2018-08-facility-simulate-conditions-venus.amp)

Scientists identify exoplanets where life could develop as it did on Earth

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Scientists have identified a group of planets outside our solar system where the same chemical conditions that may have led to life on Earth exist.

The researchers, from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology (MRC LMB), found that the chances for life to develop on the surface of a rocky planet like Earth are connected to the type and strength of light given off by its host star.

Their study, published in the journal Science Advances, proposes that stars which give off sufficient ultraviolet (UV) light could kick-start life on their orbiting planets in the same way it likely developed on Earth, where the UV light powers a series of chemical reactions that produce the building blocks of life.

https://www.eurekalert.org/pub_releases/2018-08/uoc-sie073018.php (https://www.eurekalert.org/pub_releases/2018-08/uoc-sie073018.php)
Title: Re: Astronomy Thread
Post by: Star One on 08/03/2018 08:35 pm
Probing Oort clouds around Milky Way stars with CMB surveys

Long-period comets observed in our solar system are believed to originate from the Oort cloud, which is estimated to extend from roughly a few thousand to 105 AU from the Sun. Despite many theoretical arguments for its existence, no direct observations of the cloud have been reported. Here, we explore the possibility of measuring Oort clouds around other stars through their emission at submillimeter wavelengths. Observations with the 545 and 857 GHz bands of the Planck satellite are well matched to the expected temperatures of Oort cloud bodies (on the order of 10 K). By correlating the Planck maps with catalogs of stars observed by the Gaia mission, we are able to constrain interesting regions of the exo-Oort cloud parameter space, placing limits on the total mass and the minimum size of grains in the cloud. We also explore an observed excess around the brightest and nearest stars in our sample as arising from possible exo-Oort clouds or other extended sources of thermal emission. We compare our measurements with known debris disk systems -- in the case of Vega and Fomalhaut we find a significant excess that is in agreement with measurements from Herschel. We use the measurements around Fomalhaut to constrain a possible exo-Oort cloud of that system. We argue that future CMB surveys and targeted observations with far-infrared and millimeter wavelength telescopes have the potential to detect exo-Oort clouds or other extended sources of thermal emission beyond ∼1000 AU from the parent stars.

https://arxiv.org/abs/1808.00415

Habitability in the Omega Centauri Cluster

The search for exoplanets has encompassed a broad range of stellar environments, from single stars in the solar neighborhood to multiple stars and various open clusters. The stellar environment has a profound effect on planet formation and stability evolution and is thus a key component of exoplanetary studies. Dense stellar environments, such as those found in globular clusters, provide particularly strong constraints on sustainability of habitable planetary conditions. Here, we use Hubble Space Telescope observations of the core of the Omega Centauri cluster to derive fundamental parameters for the core stars. These parameters are used to calculate the extent of the Habitable Zone of the observed stars. We describe the distribution of Habitable Zones in the cluster and compare them with the stellar density and expected stellar encounter rate and cluster dynamics. We thus determine the effect of the stellar environment within the Omega Centauri core on the habitability of planets that reside within the cluster. Our results show that the distribution of Habitable Zone outer boundaries generally lie within 0.5 AU of the host stars, but that this small cross-sectional area is counter-balanced by a relatively high rate of stellar close encounters that would disrupt planetary orbits within the Habitable Zone of typical Omega Centauri stars.

https://arxiv.org/abs/1808.00053
Title: Re: Astronomy Thread
Post by: Star One on 08/08/2018 07:54 pm
Largest haul of extrasolar planets for Japan

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Forty-four planets in solar systems beyond our own have been unveiled in one go, dwarfing the usual number of confirmations from extrasolar surveys, which is typically a dozen or less. The findings will improve our models of solar systems and may help researchers investigate exoplanet atmospheres. Novel techniques developed to validate the find could hugely accelerate the confirmation of more extrasolar planet candidates.

An international team of astronomers pooled data from U.S. space agency NASA's Kepler and the European Space Agency (ESA)'s Gaia space telescopes, as well as ground-based telescopes in the U.S. Alongside John Livingston, lead author of the study and a graduate student at the University of Tokyo, the team's combined resources led to the confirmed existence of these 44 exoplanets and described various details about them.

https://www.eurekalert.org/pub_releases/2018-08/uot-lho080718.php
Title: Re: Astronomy Thread
Post by: Star One on 08/09/2018 08:41 pm
Planetary-Mass Magnetic Powerhouse

Object is at boundary between giant planet and brown dwarf

https://public.nrao.edu/news/planetary-mass-powerhouse/
Title: Re: Astronomy Thread
Post by: Star One on 08/14/2018 05:02 pm
MSU astronomers discovered supermassive black hole in an ultracompact dwarf galaxy

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Fornax UCD3 is a part of a Fornax galaxy cluster and belongs to a very rare and unusual class of galaxies - ultracompact dwarfs. The mass of such dwarf galaxies reaches several dozen millions of solar masses and the radius, typically, does not exceed three hundred light years. This ratio between mass and size makes UCDs the densest stellar systems in the Universe.

"We have discovered a supermassive black hole in the center of Fornax UCD3. The black hole mass is 3.5 million that of the Sun, similar to the central black hole in our own Milky Way" explained Anton Afanasiev, the first author of the article, a student of the department of the Faculty of Physics, MSU.

https://www.eurekalert.org/pub_releases/2018-08/lmsu-mad081318.php
Title: Re: Astronomy Thread
Post by: Star One on 08/14/2018 08:27 pm
The Venus controversy

Quote
A lack of new missions keeps scientists guessing on what shaped the planet’s surface

http://www.planetary.org/blogs/guest-blogs/the-venus-controversy.html
Title: Re: Astronomy Thread
Post by: Star One on 08/14/2018 08:38 pm
Excavation Begins on Giant Magellan Telescope Site in Chile
Release No.:
2018-16
For Release:
Tuesday, August 14, 2018 - 11:00am
GMT hard rock excavation
Cambridge, MA -
GMTO Corporation (GMTO) today announced the start of hard rock excavation for the Giant Magellan Telescope's massive concrete pier and the foundations for the telescope's enclosure on its site at Las Campanas Observatory in Chile. The work will be performed by Minería y Montajes Conpax (known as Conpax), a construction services company that has previously performed site work for other observatories in Chile. Using a combination of hydraulic drilling and hammering, the excavation work is expected to take about five months to complete. Excavation is a key step towards the construction of the GMT, which is expected to see first light as early as 2024.

The 25-meter diameter GMT, expected to have a final weight of about 1,600 metric tons, will comprise seven 8.4-meter mirrors supported by a steel telescope structure that will be seated on the concrete pier. It will be housed inside a rotating enclosure that will measure 65 meters (~22 stories) tall and 56 meters wide. As well as working on the enclosure and telescope pier foundations, Conpax will excavate a recess in the summit rock for the lower portion of the mirror coating chamber and foundations for a utility building and tunnel on the summit.

GMTO Project Manager, Dr. James Fanson, said, "With the start of construction of the permanent buildings on the site, the GMT is showing tangible progress towards completion. We are delighted that Conpax is carrying out this important work."

The most challenging part of their work on the summit will be to excavate the solid rock of the mountain top to a depth of 7 meters (23 feet) to hold the concrete for the telescope pier. Much of this work will be done with a hydraulic rock hammer and jack hammer to ensure that the integrity of the solid bedrock below the pier is undamaged. Dr. Fanson said, "In total, we expect to remove 5,000 cubic meters or 13,300 tons of rock from the mountain and will need 330 dump truck loads to remove it from the summit."

Las Campanas Observatory, located in the southern Atacama Desert of Chile and owned by the Carnegie Institution for Science, is one of the world's premier astronomical sites, known for its clear, dark skies and stable airflow, producing exceptionally sharp images. With its unique design, the GMT will produce images that are 10 times sharper than those from the Hubble Space Telescope in the infrared region of the spectrum and will be used by astronomers to study planets around other stars and to look back to the time when the first galaxies formed.

In the past year, the GMT project has cast the fifth primary mirror segment at the Richard F. Caris Mirror Lab at the University of Arizona, announced a new partner for the project with Arizona State University, and awarded design-build contracts for the telescope mount.

This release is being issued jointly with GMTO.

The 2018 Science Book describing GMT's strengths and its potential for scientific discovery was recently released and is available for download.

GMTO Corporation (GMTO) manages the Giant Magellan Telescope project on behalf of its U.S. and international partners: Arizona State University, Astronomy Australia Ltd., The Australian National University, Carnegie Institution for Science, Fundação de Amparo à Pesquisa do Estado de São Paulo, Harvard University, Korea Astronomy and Space Science Institute, Smithsonian Institution, Texas A&M University, The University of Texas at Austin, University of Arizona, and University of Chicago.

The Smithsonian Astrophysical Observatory (SAO) leads the team responsible for the spectrograph G-CLEF (GMTConsortium Large Earth Finder). G-CLEF, when mounted on the GMT, will significantly advance the detection and characterization of planets around other stars. It is designed to detect the presence of diatomic oxygen in the atmospheres of Earth-like planets orbiting nearby stars. Terrestrial O2 is produced by living organisms. The search for life on other planets is one of the key programs of the Harvard University Origins of Life Initiative, with senior members from both Harvard College Observatory and SAO. The GMT will also enable important progress in a broad range of other fields of astrophysics, including understanding how galaxies form and evolve, and advancing the exciting new field of gravitational wave astronomy.

The Harvard-Smithsonian Center for Astrophysics also participates in the GMT through active membership on the GMTO Board and the Science Advisory Committee, as well as leadership in technical design reviews. SAO scientists have also played a leading role in designing the mirror alignment system.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
Title: Re: Astronomy Thread
Post by: Star One on 08/15/2018 08:56 pm
Iron and titanium in the atmosphere of an exoplanet

Quote
Exoplanets, planets in other solar systems, can orbit very close to their host stars. When the host star is much hotter than the sun, the exoplanet becomes as hot as a star. The hottest "ultra-hot" planet was discovered last year by American astronomers. Today, an international team led by researchers from the University of Geneva (UNIGE), who collaborated with theoreticians from the University of Bern (UNIBE), Switzerland, discovered the presence of iron and titanium vapours in the atmosphere of this planet. The detection of these heavy metals was made possible by the surface temperature of the planet, which reaches more than 4000 degrees. This discovery is published in the journal Nature.

https://m.phys.org/news/2018-08-iron-titanium-atmosphere-exoplanet.html
Title: Re: Astronomy Thread
Post by: Star One on 08/17/2018 07:05 am
Earliest galaxies found 'on our cosmic doorstep'

https://www.bbc.co.uk/news/science-environment-45198764
Title: Astronomy Thread
Post by: Star One on 08/18/2018 08:31 am
Surely a major boost for the likelihood of extraterrestrial life. Might explain the Fermi Paradox if the universe is full of intelligent marine life. Guess Douglas Adams was right.

Water-worlds are common: Exoplanets may contain vast amounts of water

Quote
Scientists have shown that water is likely to be a major component of those exoplanets (planets orbiting other stars) which are between two to four times the size of Earth. It will have implications for the search of life in our Galaxy. The work is presented at the Goldschmidt Conference in Boston.

Quote
Li Zeng continued, "Our data indicate that about 35% of all known exoplanets which are bigger than Earth should be water-rich. These water worlds likely formed in similar ways to the giant planet cores (Jupiter, Saturn, Uranus, Neptune) which we find in our own solar system. The newly-launched TESS mission will find many more of them, with the help of ground-based spectroscopic follow-up. The next generation space telescope, the James Webb Space Telescope, will hopefully characterize the atmosphere of some of them. This is an exciting time for those interested in these remote worlds".

https://m.phys.org/news/2018-08-water-worlds-common-exoplanets-vast-amounts.html
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 08/21/2018 10:48 am
Infant exoplanet weighed by Hipparcos and Gaia (http://www.esa.int/Our_Activities/Space_Science/Gaia/Infant_exoplanet_weighed_by_Hipparcos_and_Gaia) (ESA website)

Quote
The mass of a very young exoplanet has been revealed for the first time using data from ESA’s star mapping spacecraft Gaia and its predecessor, the quarter-century retired Hipparcos satellite.

Astronomers Ignas Snellen and Anthony Brown from Leiden University, the Netherlands, deduced the mass of the planet Beta Pictoris b from the motion of its host star over a long period of time as captured by both Gaia and Hipparcos.

...

In the case of Beta Pictoris b, upper limits of the planet’s mass range had been arrived at before using the radial velocity method. To obtain a better estimate, the astronomers used a different method, taking advantage of Hipparcos’ and Gaia’s measurements that reveal the precise position and motion of the planet’s host star in the sky over time.

9-13 times the mass of Jupiter.
Title: Re: Astronomy Thread
Post by: RotoSequence on 08/21/2018 08:39 pm
Apparent evidence for Hawking points in the CMB Sky (https://arxiv.org/abs/1808.01740)

Quote
Daniel An, Krzysztof A. Meissner, Roger Penrose
(Submitted on 6 Aug 2018)

    This paper presents powerful observational evidence of anomalous individual points in the very early universe that appear to be sources of vast amounts of energy, revealed as specific signals found in the CMB sky. Though seemingly problematic for cosmic inflation, the existence of such anomalous points is an implication of conformal cyclic cosmology (CCC), as what could be the Hawking points of the theory, these being the effects of the final Hawking evaporation of supermassive black holes in the aeon prior to ours. Although of extremely low temperature at emission, in CCC this radiation is enormously concentrated by the conformal compression of the entire future of the black hole, resulting in a single point at the crossover into our current aeon, with the emission of vast numbers of particles, whose effects we appear to be seeing as the observed anomalous points. Remarkably, the B-mode location found by BICEP 2 is at one of these anomalous points.
Title: Astronomy Thread
Post by: Star One on 08/21/2018 10:14 pm
This article doesn’t sound terrible convinced by the paper with the use of the term eccentric  and the comments underneath are pretty scathing.

https://www.livescience.com/63392-black-holes-from-past-universes.html
Title: Re: Astronomy Thread
Post by: RotoSequence on 08/21/2018 11:05 pm
This article doesn’t sound terrible convinced by the paper with the use of the term eccentric  and the comments underneath are pretty scathing.

https://www.livescience.com/63392-black-holes-from-past-universes.html

Roger Penrose isn't a name that warrants scoffing at and ignoring in favor of anonymous internet commentators.
Title: Re: Astronomy Thread
Post by: QuantumG on 08/22/2018 04:28 am
Roger Penrose isn't a name that warrants scoffing at and ignoring in favor of anonymous internet commentators.

Agreed. It's good to see him get back to his own field... where perhaps it's less obvious that he went batty a decade ago.
Title: Re: Astronomy Thread
Post by: as58 on 08/22/2018 04:39 am
Penrose has been pushing his conformal cyclic cosmology for many years and this isn't the first time that he has claimed to find some features in the CMB that prove his theory. Very few people have been convinced.
Title: Re: Astronomy Thread
Post by: RotoSequence on 08/22/2018 05:15 am
Penrose has been pushing his conformal cyclic cosmology for many years and this isn't the first time that he has claimed to find some features in the CMB that prove his theory. Very few people have been convinced.

Fair enough.
Title: Astronomy Thread
Post by: Star One on 08/22/2018 05:57 am
Penrose has been pushing his conformal cyclic cosmology for many years and this isn't the first time that he has claimed to find some features in the CMB that prove his theory. Very few people have been convinced.

Fair enough.

Which was all pointed out in the article.
Title: Re: Astronomy Thread
Post by: RotoSequence on 08/22/2018 06:03 am
Which if you had read the article you would have seen pointed out.

And reading the article makes the critique offered seem even less notable than I'd initially thought. Who hasn't gotten into a debate with Sean Carroll at this point?  ;)
Title: Re: Astronomy Thread
Post by: Star One on 08/22/2018 06:56 am
Eerie Sky Glow Called 'Steve' Isn't an Aurora, Is 'Completely Unknown' to Science

Quote
Given its coincidence with the northern lights, Steve was just thought to be part of the aurora — the shimmering sheets of nighttime color that appear in the sky when charged plasma particles streak out of the sun, sail across space on solar winds and jolt down Earth's magnetic field toward the planet's poles. However, a new study published today (Aug. 20) in the journal Geophysical Research Letters suggests that such a simple explanation might not apply.

Quote
For their new study, the team combined images taken by a network of ground-based cameras with data collected from one of the National Oceanic and Atmospheric Administration's Polar-orbiting Operational Environmental Satellites, which were equipped with instruments capable of detecting charged particles descending through Earth's atmosphere.

Contrary to the findings from the Steve study published earlier this year, the satellite did not detect any charged particles raining down toward Earth's magnetic-field lines, indicating that whatever created Steve did not follow the same rules as the solar particles that create the aurora.

https://www.livescience.com/63385-steve-not-aurora-mystery-phenomenon.html

Title: Re: Astronomy Thread
Post by: Star One on 08/22/2018 08:24 pm
Stars memorize rebirth of our home galaxy

Quote
The Milky Way galaxy has died once before, and we are now in what is considered its second life. Calculations by Masafumi Noguchi (Tohoku University) have revealed previously unknown details about the Milky Way. These were published in the July 26 edition of Nature.

https://phys.org/news/2018-08-stars-rebirth-home-galaxy
Title: Re: Astronomy Thread
Post by: dougkeenan on 08/23/2018 06:49 pm
working link -> https://phys.org/news/2018-08-stars-rebirth-home-galaxy.html
Title: Astronomy Thread
Post by: Star One on 08/28/2018 08:01 pm
Eclipsing binaries in the open cluster Ruprecht 147. I: EPIC 219394517

Eclipsing binaries in star clusters offer more stringent tests of stellar evolution theory than field binaries because models must not only match the binary properties, but also the radiative properties of all other cluster members at a single chemical composition and a single age. Here we report new spectroscopic observations of the G type, detached eclipsing binary EPIC 219394517 in the open cluster Ruprecht 147 ([Fe/H] = +0.10), which was observed in late 2015 by the K2 mission. A joint analysis of our radial-velocity measurements and the K2 light curve shows the 6.5 day orbit to be very nearly circular. We derive highly precise masses of 1.0782 +/- 0.0019 Msun and 1.0661 (+0.0027/-0.0021) Msun, radii of 1.055 +/- 0.011 Rsun and 1.042 +/- 0.012 Rsun, and effective temperatures of 5930 +/- 100 K and 5880 +/- 100 K for the primary and secondary, respectively. The distance we infer, 283 (+18/-16) pc, corresponds to a parallax in good agreement with the Gaia/DR2 value for the star. Current stellar evolution models from the MIST and PARSEC series match the above physical properties very well at ages of 2.48 and 2.65 Gyr. Isochrones for these same ages and the measured composition, along with our reddening estimate for EPIC 219394517, also show generally good agreement with the optical and near-infrared color-magnitude diagrams of the cluster, which can be constructed with no free parameters as the distances of all member stars are known from Gaia.

https://arxiv.org/abs/1808.07482

Meteorite data indicate Jupiter underwent distinct growth phases

Quote
Analysis of meteorite data indicates the growth of Jupiter into the solar system’s most massive planet was held up for about two million years during a phase in which kilometre-size planetesimals crashed into it, releasing heat that prevented rapid cooling, contraction and further gas accretion.

https://astronomynow.com/2018/08/27/meteorite-data-indicate-jupiter-underwent-distinct-growth-phases/

Title: Re: Astronomy Thread
Post by: Star One on 08/30/2018 08:11 pm
Unstoppable Monster in the Early Universe - ALMA obtains most detailed view of distant starburst galaxy

Quote
Astronomers obtained the most detailed anatomy chart of a monster galaxy located 12.4 billion light-years away. Using the Atacama Large Millimeter/submillimeter Array (ALMA), the team revealed that the molecular clouds in the galaxy are highly unstable, which leads to runaway star formation. Monster galaxies are thought to be the ancestors of the huge elliptical galaxies in today’s Universe, therefore these findings pave the way to understand the formation and evolution of such galaxies.

https://alma-telescope.jp/en/news/press/aztecone-201808
Title: Re: Astronomy Thread
Post by: Star One on 09/01/2018 02:16 pm
Water worlds could support life, study says

Quote
Analysis by UChicago, Penn State scientists challenges idea that life requires ‘Earth clone’

https://news.uchicago.edu/story/water-worlds-could-support-life-study-says
Title: Re: Astronomy Thread
Post by: Star One on 09/03/2018 06:37 am
How a NASA scientist looks in the depths of the Great Red Spot to find water on Jupiter

Quote
But one critical question has bedeviled astronomers for generations: Is there water deep in Jupiter's atmosphere, and if so, how much?

Gordon L. Bjoraker, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, reported in a recent paper in the Astronomical Journal that he and his team have brought the Jovian research community closer to the answer.

https://m.phys.org/news/2018-08-nasa-scientist-depths-great-red.html
Title: Re: Astronomy Thread
Post by: Star One on 09/07/2018 07:48 pm
Polaris, the North Star
Friday, September 7, 2018
Science Update - A look at CfA discoveries from recent journals
The North Star, Polaris, is a Cepheid variable: one whose mass, age and physical conditions generate periodic oscillations with a period proportional to the star's intrinsic luminosity. This extraordinarily useful property of Cepheid variables, discovered and calibrated at Harvard by Henrietta Leavitt starting in 1908, allows them to be used as cosmic distance calibrators. By comparing the intrinsic brightness as determined from the period (which is easily measured) with the measured brightness, the period-luminosity relationship, a precise distance can in principle be obtained. Cepheids in nearby galaxies that are receding from us provide the basis for the famous distance-velocity relationship of galaxies that underpins the expanding model of the universe (the "big bang" model). Cepheids are so important that they have also become benchmarks for testing our understanding of stellar evolution.

Polaris is not only famous as the beacon for early navigators, it is also the closest Cepheid to earth (445.5 light-years away), and a subject of intense study. It is a member of a triple system, and one source of confusion about its development has been the extent to which its companion stars could have affected its evolution. The star we can see by eye, Polaris Aa, has a close companion, Polaris Ab that orbits it in 29.59 years; a third star, Polaris B, orbits these two but is one hundred times farther away. Two more stars nearby, Polaris C and D, might also be faint companions.

Three CfA astronomers, Nancy Remage Evans, Margarita Karovska, and Evan Tingle led a team that has been monitoring Polaris with the Hubble Space Telescope since 2005. In their images they are able to resolve the two stars Aa and Ab and to follow their apparent separation which varies during the orbit; the most recent separation of these two in their mutual elliptical orbit is only about twelve astronomical units (about the distance of Saturn from the Sun). They have now incorporated into their results the newly released data from the Gaia mission, a spacecraft that has been measuring with new precision the distances to over a billion stars. The distance to Polaris (the above-mentioned value is from Gaia) settles a long-standing uncertainty about the distance which earlier authors found to be between about 326 light-years to 522 light-years. The newly reliable distance also fixes the intrinsic luminosity and thus enables a more careful calibration of Polaris’ period-luminosity relationship.

The situation is not what astronomers had previously thought. Polaris has a significantly lower mass (3.45 solar-masses, with an uncertainty of about 22%) than was predicted by conventional Cepheid models (one value was close to seven solar-masses). There is also evidence that Polaris Aa has undergone some mass loss, that its age is slightly older than expected from the models, and (not least) that the evolution may have been very complicated indeed with the triple system resulting from a prior merger event. While these critical issues do not dramatically alter the general conclusions about Cepheid stars, they do show that further refinements to our understanding of Cepheids will be vital to a more accurate and unambiguous period-luminosity relationship; tracking the orbit longer will help.
Title: Re: Astronomy Thread
Post by: Star One on 09/10/2018 08:32 pm
The Sands of Phobos: The Martian moon's eccentric orbit refreshes its surface

Ronald-Louis Ballouz, Nicola Baresi, Sarah T. Crites, Yasuhiro Kawakatsu, Masaki Fujimoto
(Submitted on 7 Sep 2018)
The surface of the Martian moon Phobos exhibits two distinct geologic units, known as the red and blue units. The provenance of these regions is uncertain yet crucial to understanding the origin of the Martian moon and its interaction with the space environment. Here we show that Phobos' orbital eccentricity can cause sufficient grain motion to refresh its surface, suggesting that space weathering is the likely driver of the dichotomy on the moon's surface. In particular, we predict that blue regions are made up of pristine endogenic material that can be uncovered in steep terrain subject to large variations in the tidal forcing from Mars. The predictions of our model are consistent with current spacecraft observations which show that blue units are found near these regions.

https://arxiv.org/abs/1809.02520
Title: Re: Astronomy Thread
Post by: Star One on 09/10/2018 08:50 pm
Artificial intelligence helps track down mysterious cosmic radio bursts

Quote
While most fast radio bursts are one-offs, the source here, FRB 121102, is unique in emitting repeated bursts. This behavior has drawn the attention of many astronomers hoping to pin down the cause and the extreme physics involved in fast radio bursts.

The AI algorithms dredged up the radio signals from data were recorded over a five-hour period on Aug. 26, 2017, by the Green Bank Telescope in West Virginia. An earlier analysis of the 400 terabytes of data employed standard computer algorithms to identify 21 bursts during that period. All were seen within one hour, suggesting that the source alternates between periods of quiescence and frenzied activity, said Berkeley SETI postdoctoral researcher Vishal Gajjar.

UC Berkeley Ph.D. student Gerry Zhang and collaborators subsequently developed a new, powerful machine-learning algorithm and reanalyzed the 2017 data, finding an additional 72 bursts not detected originally. This brings the total number of detected bursts from FRB 121102 to around 300 since it was discovered in 2012.

https://m.phys.org/news/2018-09-artificial-intelligence-track-mysterious-cosmic.html

Title: Re: Astronomy Thread
Post by: Star One on 09/12/2018 08:37 pm
Medium-sized satellites of large Kuiper belt objects

Michael E. Brown, Bryan J. Butler
(Submitted on 22 Jan 2018 (v1), last revised 10 Sep 2018 (this version, v2))
While satellites of mid- to small-Kuiper belt objects tend to be similar in size and brightness to their primaries, the largest Kuiper belt objects preferentially have satellites with small fractional brightness. In the two cases where the sizes and albedos of the small faint satellites have been measured, these satellites are seen to be small icy fragments consistent with collisional formation. Here we examine Dysnomia and Vanth, the satellites of Eris and Orcus, respectively. Using the Atacama Large Millimeter Array, we obtain the first spatially resolved observations of these systems at thermal wavelengths. We find a diameter for Dysnomia of 700+/-115 km and for Vanth of 475+/-75 km, with albedos of 0.04_+0.02_-0.01 and 0.08+/-0.02 respectively. Both Dysnomia and Vanth are indistinguishable from typical Kuiper belt objects of their size. Potential implications for the formation of these types of satellites are discussed.

https://arxiv.org/abs/1801.07221

Title: Astronomy Thread
Post by: Star One on 09/12/2018 08:57 pm
A Galactic Gem

ESO’s FORS2 instrument captures stunning details of spiral galaxy NGC 3981

This wonderful image shows the resplendent spiral galaxy NGC 3981 suspended in the inky blackness of space. This galaxy, which lies in the constellation of Crater (the Cup), was imaged in May 2018 using the FOcal Reducer and low dispersion Spectrograph 2 (FORS2) instrument on ESO’s Very Large Telescope (VLT).

FORS2 is mounted on Unit Telescope 1 (Antu) of the VLT at ESO’s Paranal Observatory in Chile. Amongst the host of cutting-edge instruments mounted on the four Unit Telescopes of the VLT, FORS2 stands apart due to its extreme versatility. This ”Swiss Army knife” of an instrument is able to study a variety of astronomical objects in many different ways — as well as being capable of producing beautiful images like this one.

The sensitive gaze of FORS2 revealed NGC 3981’s spiral arms, strewn with vast streams of dust and star-forming regions, and a prominent disc of hot young stars. The galaxy is inclined towards Earth, allowing astronomers to peer right into the heart of this galaxy and observe its bright centre, a highly energetic region containing a supermassive black hole. Also shown is NGC 3981’s outlying spiral structure, some of which appears to have been stretched outwards from the galaxy, presumably due to the gravitational influence of a past galactic encounter.

NGC 3981 certainly has many galactic neighbours. Lying approximately 65 million light years from Earth, the galaxy is part of the NGC 4038 group, which also contains the well-known interacting Antennae Galaxies. This group is part of the larger Crater Cloud, which is itself a smaller component of the Virgo Supercluster, the titanic collection of galaxies that hosts our own Milky Way galaxy.

NGC 3981 is not the only interesting feature captured in this image. As well as several foreground stars from our own galaxy, the Milky Way, FORS2 also captured a rogue asteroid streaking across the sky, visible as the faint line towards the top of the image. This particular asteroid has unwittingly illustrated the process used to create astronomical images, with the three different exposures making up this image displayed in the blue, green and red sections of the asteroid’s path.

This image was taken as part of ESO’s Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. In case the data collected could be useful for future scientific purposes, these observations are saved and made available to astronomers through ESO’s science archive.

https://www.eso.org/public/news/eso1830/

https://www.youtube.com/watch?v=fF35CwAIl2A

https://www.youtube.com/watch?v=GKL7QdjUoCE
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 09/17/2018 06:15 am
The hot Jupiter period-mass distribution as a signature of in situ formation (https://arxiv.org/abs/1809.05517) (Bailey & Batygin) (arXiv)

Quote
(Abstract)
More than two decades after the widespread detection of Jovian-class planets on short-period orbits around other stars, their dynamical origins remain imperfectly understood. In the traditional narrative, these highly irradiated giant planets, like Jupiter and Saturn, are envisioned to have formed at large stello-centric distances and to have subsequently undergone large-scale orbital decay. Conversely, more recent models propose that a large fraction of hot Jupiters could have formed via rapid gas accretion in their current orbital neighborhood. In this study, we examine the period-mass distribution of close-in giant planets, and demonstrate that the inner boundary of this population conforms to the expectations of the in-situ formation scenario. Specifically, we show that if conglomeration unfolds close to the disk's inner edge, the semi-major axis - mass relation of the emergent planets should follow a power law a∝M−2/7 - a trend clearly reflected in the data. We further discuss corrections to this relationship due to tidal decay of planetary orbits. Although our findings do not discount orbital migration as an active physical process, they suggest that the characteristic range of orbital migration experienced by giant planets is limited.

Despite the title and abstract, the paper seems to consider the sem-major axis - mass distribution!? Seems an odd mistake to make.

I like the fact that hot-Jupiter formation by migration is described as "the traditional narrative"! :) It's only been ~25 years since the first was discovered - just shows how fast this field has been moving.
Title: Astronomy Thread
Post by: Star One on 09/19/2018 07:38 pm
 This Pulsar is Giving Off Weird Infrared Light and We’re Not Sure Why (https://www.smithsonianmag.com/smart-news/pulsar-giving-weird-infrared-light-and-were-not-sure-why-180970331/)

Stars in Milky Way moving ‘like ripples on pond’ after near collision with another galaxy (https://www.independent.co.uk/news/science/milky-way-stars-galaxies-gaia-space-observatory-esa-a8545016.html/)

The Moon Is Electric—Especially When It's Full (https://www.nationalgeographic.com/science/2018/09/news-full-moon-electric-ionosphere-nasa-artemis-space/)
Title: Re: Astronomy Thread
Post by: Star One on 09/24/2018 01:04 pm
Planet-Planet Tides in the TRAPPIST-1 System

Jason T. Wright
(Submitted on 21 Sep 2018)
The star TRAPPIST-1 hosts a system of seven transiting, terrestrial exoplanets apparently in a resonant chain, at least some of which are in or near the Habitable Zone. Many have examined the roles of tides in this system, as tidal dissipation of the orbital energy of the planets may be relevant to both the rotational and orbital dynamics of the planets, as well as their habitability. Generally, tides are calculated as being due to the tides raised on the planets by the star, and tides raised on the star by the planets. I write this research note to point out a tidal effect that may be at least as important as the others in the TRAPPIST-1 system and which is so far unremarked upon in the literature: planet-planet tides. Under some reasonable assumptions, I find that for every planet p in the TRAPPIST-1 system there exists some other planet q for which the planet-planet dynamical tidal strain is within an order of magnitude of the stellar eccentricity tidal strain, and that the effects of planet f on planet g are in fact greater than that of the star on planet g. It is thus not obvious that planet-planet tides can be neglected in the TRAPPIST-1 exoplanetary system, especially the tides on planet g due to planet f, if the planets are in synchronous rotation.
Comments:3 pp Research Note of the AAS
Subjects:Earth and Planetary Astrophysics (astro-ph.EP)
Journal reference:Wright (2018) Res. Notes AAS, 2, 175
DOI:10.3847/2515-5172/aae260
Cite as:arXiv:1809.08166 [astro-ph.EP]
 (or arXiv:1809.08166v1 [astro-ph.EP] for this version)

https://arxiv.org/abs/1809.08166
Title: Re: Astronomy Thread
Post by: Star One on 09/26/2018 03:53 pm
BETA PIC B: AN EXOPLANET EMERGES FROM THE GLARE

Quote
Subsequent observations taken over the years showed something incredible: The actual motion of the planet as it orbited the star! Images taken in 2009 and 2010 showed that it had moved from one side of the star to the other: Clear evidence of orbital motion. We happen to see its orbit almost (but not exactly) edge-on, so we see it move back and forth over the period orbit.

In the following years the planet made it ‘round the bend, and started heading back toward conjunction (closest approach) with Beta Pic, which happened in late September 2017. After that it was too close to the star to see, lost in the glare.

But now it has re-emerged, and was captured in an image yet again by the Spectro-Polarimetric High-contrast Exoplanet REsearch (or just SPHERE) detector on the ginormous 8.2-meter Very Large Telescope in Chile. This was taken just days ago, on September 17, 2018, and clearly shows the planet:

https://www.syfy.com/syfywire/beta-pic-b-an-exoplanet-emerges-from-the-glare
Title: Re: Astronomy Thread
Post by: Alpha_Centauri on 09/28/2018 08:10 am
Sort of astronomy but also maybe (...or maybe not) big news for particle physics.

A new preprint has been posted claiming that a set of cosmic ray events from a balloon-borne experiment cannot be explained by the Standard Model and instead propose they come from a low-mass supersymmetric particle.  Should be noted the balloon experiment team themselves are quite cautious about the earth-tunnelling interpretation despite having previously suggested it.

https://www.sciencemag.org/news/2018/09/oddball-particles-tunneling-through-earth-could-point-new-physics
Quote
Oddball particles tunneling through Earth could point to new physics
Twice in the past 13 years, particles from outer space tunneled through Earth and up into the atmosphere above Antarctica, triggering faint pulses of radio waves that were picked up by a balloon-borne detector 35 kilometers above the ice cap. Those two events poke a hole in physicists’ standard model of fundamental particles and forces, and point to the existence of new particles, a team of astrophysicists argues in a new study.

https://www.livescience.com/63692-standard-model-broken-supersymmetry-new-physics.html
Quote
Bizarre Particles Keep Flying Out of Antarctica's Ice, and They Might Shatter Modern Physics

There's something mysterious coming up from the frozen ground in Antarctica, and it could break physics as we know it.

Physicists don't know what it is exactly. But they do know it's some sort of cosmic ray — a high-energy particle that's blasted its way through space, into the Earth, and back out again. But the particles physicists know about — the collection of particles that make up what scientists call the Standard Model (SM) of particle physics — shouldn't be able to do that. Sure, there are low-energy neutrinos that can pierce through miles upon miles of rock unaffected. But high-energy neutrinos, as well as other high-energy particles, have "large cross-sections." That means that they'll almost always crash into something soon after zipping into the Earth and never make it out the other side.

The ANITA Anomalous Events as Signatures of a Beyond Standard Model Particle, and Supporting Observations from IceCube
https://arxiv.org/abs/1809.09615
Title: Re: Astronomy Thread
Post by: Star One on 09/28/2018 03:05 pm
And I always thought super-symmetry would turn out to be load of hogs wash, but it seems possibly not.
Title: Astronomy Thread
Post by: Star One on 10/01/2018 07:33 am
Surprised to see Martin Rees raising this sort of stuff in his book, mind you it maybe he’s a victim of selective quoting with this article.

Earth Could Be Crushed to The Size of a Soccer Field by Particle Accelerator Experiments, Astronomer Warns (https://www.sciencealert.com/cosmologist-martin-rees-warns-earth-smooshed-to-size-of-a-soccer-pitch-330-ft-by-particle-accelerator-experiments-lhc)
Title: Astronomy Thread
Post by: Star One on 10/01/2018 07:50 pm
Back for a second visit since being discovered.

Don't look now but there's a skull-shaped 'Halloween asteroid' approaching Earth (https://www.mnn.com/earth-matters/space/blogs/skull-shaped-halloween-asteroid-approaching-earth)

UCSB experimental cosmologist Philip Lubin and his group use photonics to search Andromeda for signs of alien life (http://www.news.ucsb.edu/2018/019198/where-are-they)
Title: Astronomy Thread
Post by: Star One on 10/02/2018 08:51 pm
Black holes ruled out as universe's missing dark matter (https://phys.org/news/2018-10-black-holes-universe-dark.amp)

Quote
For one brief shining moment after the 2015 detection of gravitational waves from colliding black holes, astronomers held out hope that the universe's mysterious dark matter might consist of a plenitude of black holes sprinkled throughout the universe.

Quote
Based on a statistical analysis of 740 of the brightest supernovas discovered as of 2014, and the fact that none of them appear to be magnified or brightened by hidden black hole "gravitational lenses," the researchers concluded that primordial black holes can make up no more than about 40 percent of the dark matter in the universe. Primordial black holes could only have been created within the first milliseconds of the Big Bang as regions of the universe with a concentrated mass tens or hundreds of times that of the sun collapsed into objects a hundred kilometers across.

The results suggest that none of the universe's dark matter consists of heavy black holes, or any similar object, including massive compact halo objects, so-called MACHOs.
Title: Astronomy Thread
Post by: Star One on 10/03/2018 07:07 pm
Couple of new videos from Cool Worlds about their Exomoon candidate.

https://www.youtube.com/watch?v=eGjgD27Dtpc

https://www.youtube.com/watch?v=vlcc2MdYaik

And here’s an accompanying article on the latest updates.

https://www.centauri-dreams.org/2018/10/03/kepler-1625b-orbited-by-an-exomoon/
Title: Re: Astronomy Thread
Post by: jebbo on 10/04/2018 06:46 am
Kepler-1625b i is tantalising, but I have to say I'm still somewhat sceptical.

The original exomoon signatures in the Kepler transit data don't look anywhere near as compelling, thanks to better removal of systematics in the latest DR. The TTVs are pretty compelling, and the other new HST stuff is interesting though I don't think it has high significance (I don't really know how to assign a proper significance number to this! For exoplanets it's easy(-ish) ;) ).

The data is consistent with it being an exomoon, but as the article says, eliminating a 2nd planet would be a big step towards proving it.  On the plus side, it transits so all we need to do is get more observations

--- Tony
Title: Re: Astronomy Thread
Post by: Bynaus on 10/04/2018 07:08 am
@jebbo: Regarding significance of the HST result, what do you think of the aproach the authors actually take? Their M model seems to be strongly favored over the P (planet only), T (TTVs) and Z (Moon but only TTV aspect) models.
Title: Astronomy Thread
Post by: Star One on 10/04/2018 08:21 pm
Kepler-1625b i is tantalising, but I have to say I'm still somewhat sceptical.

The original exomoon signatures in the Kepler transit data don't look anywhere near as compelling, thanks to better removal of systematics in the latest DR. The TTVs are pretty compelling, and the other new HST stuff is interesting though I don't think it has high significance (I don't really know how to assign a proper significance number to this! For exoplanets it's easy(-ish) ).

The data is consistent with it being an exomoon, but as the article says, eliminating a 2nd planet would be a big step towards proving it.  On the plus side, it transits so all we need to do is get more observations

--- Tony

I hope you’re not basing your scepticism on the fact that the HST observations ran out of time and therefore missed the exit point of the moon’s transit.

And yes they are almost stretching Wide Field camera 3 to breaking point with what they were asking it to observe as a general point, but again I am not sure that’s worthy of blanket scepticism.
Title: Astronomy Thread
Post by: Star One on 10/04/2018 08:46 pm
Cool worlds are doing a Q & A at the moment.

https://youtu.be/KWLHO8nTZm8

Or NASA finds evidence of exomoon, join NASA scientists on the 5th October at 1pm ET.

https://www.youtube.com/watch?v=JZvBZa70jRI
Title: Re: Astronomy Thread
Post by: jebbo on 10/05/2018 07:26 am
@jebbo: Regarding significance of the HST result, what do you think of the approach the authors actually take? Their M model seems to be strongly favored over the P (planet only), T (TTVs) and Z (Moon but only TTV aspect) models.

The approach is good ... but the significance of the Kepler moon signatures in the 3 transits has dropped markedly, and the result depends strongly on the one from Hubble (I think this means M will be more favoured just because of the number of free parameters). 

So if all we had was the latest Kepler data, I doubt it would have been flagged as a candidate at all.

On the Hubble moon transit, as noted by Star One, it has no data post egress. Not fatal, but it would have been VERY nice to have data after the candidate transit as this would help enormously with the trend model.

It is still by far the best exomoon candidate we have, and I hope more data confirms it.

--- Tony
Title: Re: Astronomy Thread
Post by: Star One on 10/05/2018 11:52 am
I think this moon if it exists is more likely a planetary capture as though they state it is allowable for it to have formed with its parent it is on the very upper limits. If it is a planetary capture could the moon have moons in turn?
Title: Re: Astronomy Thread
Post by: jebbo on 10/05/2018 12:03 pm
If it is a planetary capture could the moon have moons in turn?

Phil Plait discussed this on Twitter [ tl;dr yes ]

https://twitter.com/BadAstronomer/status/1047564407952293888 (https://twitter.com/BadAstronomer/status/1047564407952293888)

--- Tony
Title: Re: Astronomy Thread
Post by: jebbo on 10/09/2018 08:36 am
Further to the "moons of moons" thing, here is a new analysis:

Can Moons Have Moons?
Quote
Each of the giant planets within the Solar System has large moons but none of these moons have their own moons (which we call submoons). By analogy with studies of moons around short-period exoplanets, we investigate the dynamical stability of submoons. We find that 10 km-scale submoons can only survive around large (1000 km-scale) moons on wide-separation orbits. Tidal dissipation destabilizes the orbits of submoons around moons that are small or too close to their host planet; this is the case for most of the Solar System's moons. A handful of known moons are, however, capable of hosting long-lived submoons: Saturn's moons Titan and Iapetus, Jupiter's moon Callisto, and Earth's Moon. Based on its inferred mass and orbital separation, the newly-discovered exomoon candidate Kepler-1625b-I can, in principle, host submoons, although its large orbital inclination may pose a difficulty for dynamical stability. The existence, or lack thereof, of submoons, may yield important constraints on satellite formation and evolution in planetary systems.

Arxiv link (https://arxiv.org/abs/1810.03304)

--- Tony
Title: Astronomy Thread
Post by: Star One on 10/09/2018 08:08 pm
Quote
The
@NASA
 #technosigs18 workshop talks are now up!

(link: https://www.hou.usra.edu/meetings/technosignatures2018/agenda/) hou.usra.edu/meetings/techn…
@jilltarter

https://twitter.com/Astro_Wright/status/1049686230475128832

Quote
Michael New discusses why the workshop was about "technosignatures" and not #SETI at 13:00 ish:
(link: https://www.hou.usra.edu/meetings/technosignatures2018/presentation/new.mp4) hou.usra.edu/meetings/techn…
Somewhat archly admits that the term "SETI" tends to provoke "antibodies" at
@NASA

https://twitter.com/Astro_Wright/status/1049688300066414593

Quote
Also, Martin Still is mistaken in that video about XRP being open to #SETI proposals—as recently as last year such proposals were explicitly out of scope of that program.

https://twitter.com/Astro_Wright/status/1049689753812180993
Title: Re: Astronomy Thread
Post by: eeergo on 10/10/2018 06:48 pm

https://www.cta-observatory.org/lst-1_inauguration/


LST(Large-Sized Telescope)-1 for the Cherenkov Telescope Array (CTA) Northern-hemisphere complex in Spain's La Palma island (Canaries) off the coast of Morocco/Western Sahara has been inaugurated today. It was under construction for exactly 3 years. It is the prototype for 8 more LSTs (3 more in Spain and 4 more in Chile). It can reposition to any point in the sky within 20s of the command.


It will be complemented by 40 MSTs and 70 SSTs (Medium- and Small-Sized Telescopes) as well as SCTs (Schwarzschild-Couder Telescopes) to form the CTA Observatory, a collaboration of 31 different countries in two sites: the Canarian one at El Roque de los Muchachos and a Chilean Southern-hemisphere complex in Paranal. In its full configuration (~100 telescopes) it will be 10x more sensitive than current telescopes to the highest-energy photons ever recorded (20-300 GeV).

https://twitter.com/astro_duque/status/1050058265105760257
Title: Astronomy Thread
Post by: Star One on 10/13/2018 09:18 am
Dying Star Emits a Whisper (http://m.caltech.edu/news/dying-star-emits-whisper-84057)

Quote
A Caltech-led team of researchers has observed the peculiar death of a massive star that exploded in a surprisingly faint and rapidly fading supernova. These observations suggest that the star has an unseen companion, gravitationally siphoning away the star's mass to leave behind a stripped star that exploded in a quick supernova. The explosion is believed to have resulted in a dead neutron star orbiting around its dense and compact companion, suggesting that, for the first time, scientists have witnessed the birth of a compact neutron star binary system.

AUSSIE TELESCOPE ALMOST DOUBLES KNOWN NUMBER OF MYSTERIOUS ‘FAST RADIO BURSTS’ (https://www.icrar.org/bursts/)

Quote
Australian researchers using a CSIRO radio telescope in Western Australia have nearly doubled the known number of ‘fast radio bursts’— powerful flashes of radio waves from deep space.

The team’s discoveries include the closest and brightest fast radio bursts ever detected.
Title: Re: Astronomy Thread
Post by: Star One on 10/16/2018 09:06 pm
Massive planets spotted near young star leave astronomers scratching their heads (https://bgr.com/2018/10/16/gas-giant-exoplanets-cl-tau-star-system/)

Quote
The star known as Cl Tau lies roughly 500 light years away, which is a stone’s throw in astronomical terms, and scientists now believe it’s being orbited by some truly massive planets. That wouldn’t necessarily be odd, as exoplanets are spotted on a regular basis with modern telescope technology, but what makes this system so unique is that the star itself is only thought to be around two million years old.
Title: Re: Astronomy Thread
Post by: Bynaus on 10/16/2018 10:18 pm
"spotted" - note that the planets themselves have not been seen (except for the hot jupiter, which is visible in the RV data), only inferred. There have been suggestions that the gaps in these disks might actually represent condensation fronts of different chemical species. Proceed with caution on top of some grains of salt.
Title: Re: Astronomy Thread
Post by: Star One on 10/17/2018 06:24 am
Here’s What the First Images from the Event Horizon Might Look Like (https://www.universetoday.com/140268/heres-what-the-first-images-from-the-event-horizon-might-look-like/)
Title: Re: Astronomy Thread
Post by: Star One on 10/18/2018 06:39 am
Largest Galaxy Proto-Supercluster Found (https://www.eso.org/public/news/eso1833/)

Quote
An international team of astronomers using the VIMOS instrument of ESO’s Very Large Telescope have uncovered a titanic structure in the early Universe. This galaxy proto-supercluster — which they nickname Hyperion — was unveiled by new measurements and a complex examination of archive data. This is the largest and most massive structure yet found at such a remote time and distance — merely 2 billion years after the Big Bang.
Title: Re: Astronomy Thread
Post by: Star One on 10/26/2018 05:53 am
 A first 'snapshot' of the complete spectrum of neutrinos emitted by the sun (https://www.eurekalert.org/pub_releases/2018-10/uoma-af101918.php)

Quote
About 99 percent of the Sun's energy emitted as neutrinos is produced through nuclear reaction sequences initiated by proton-proton (pp) fusion in which hydrogen is converted into helium, say scientists including physicist Andrea Pocar at the University of Massachusetts Amherst. Today they report new results from Borexino, one of the most sensitive neutrino detectors on the planet, located deep beneath Italy's Apennine Mountains.
Title: Re: Astronomy Thread (full solar neutrino spectroscopy)
Post by: eeergo on 10/26/2018 11:06 am
A first 'snapshot' of the complete spectrum of neutrinos emitted by the sun (https://www.eurekalert.org/pub_releases/2018-10/uoma-af101918.php)

Quote
About 99 percent of the Sun's energy emitted as neutrinos is produced through nuclear reaction sequences initiated by proton-proton (pp) fusion in which hydrogen is converted into helium, say scientists including physicist Andrea Pocar at the University of Massachusetts Amherst. Today they report new results from Borexino, one of the most sensitive neutrino detectors on the planet, located deep beneath Italy's Apennine Mountains.

Thanks for linking this, Borexino is one of the neutrino experiments I work on :) If anyone would like to know more about the physics or the detector technical details, feel free to contact me!
Title: Re: Astronomy Thread
Post by: Star One on 10/31/2018 08:16 pm
ESOcast 181 Light: Most Detailed Observations of Material Orbiting close to a Black Hole (4K UHD)

https://youtu.be/hXrJDXm6mn4
Title: Re: Astronomy Thread
Post by: Star One on 10/31/2018 08:27 pm
 ‘Zombie’ stars return from the dead (https://www.llnl.gov/news/‘zombie’-stars-return-dead)

Quote
The research explored whether a dormant white dwarf star — sometimes referred to as a “zombie” star — could reignite if it had a close encounter with an intermediate-mass black hole. While data exists to corroborate the existence of supermassive black holes, there have been no confirmed observations of black holes in the intermediate class, which range in size from 100 to 100,000 solar masses. This intermediate class, the research team posited, might offer just the right amount of gravitational force to reignite a white dwarf before it’s torn apart.

The team ran supercomputer simulations of dozens of different close encounter scenarios to test this theory. Not only did they find that a close encounter would reignite the once-dead star, but they saw evidence that the process could create significant electromagnetic and gravitational wave energies that might be visible from detectors in near-Earth orbit. The research was published in the September issue of The Astrophysical Journal.
Title: Re: Astronomy Thread
Post by: Star One on 11/01/2018 10:59 pm
Could we detect planets around dead stars?

https://youtu.be/_gK3ABpgKZM
Title: Astronomy Thread
Post by: Star One on 11/02/2018 07:50 pm
 ICE VII: SCIENTISTS DISCOVER HOW EXTRAORDINARY ICE FOUND DEEP BELOW THE EARTH GROWS AT OVER 1,000 MILES PER HOUR (https://www.newsweek.com/ice-vii-scientists-discover-how-extraordinary-ice-found-deep-below-earth-1198346)

Quote
Understanding more about the high-pressure phases of ice VII could even have important implications when it comes to searching for life outside the Solar System, according to Belof.

Astronomers think that there may be many exoplanets covered in vast liquid water oceans like Earth. So far, several promising candidate "ocean worlds" have been detected (although we currently do not have the technology to confirm the presence of oceans on distant worlds at present).

Liquid water is essential for life as we know it, but what happens to it under extreme conditions?

“Water on these ocean worlds, under bombardment from other planetary bodies such as meteors or comets, undergoes intense changes for which life might not survive,” Belof said.

“The shock waves launched by the explosions from these planetary impact events can compress water to a pressure over 10,000 times that found on the Earth’s surface and cause the water to freeze into ice VII,” he said.

This suggests that these ocean worlds may have a layer of ice VII deep below their liquid water oceans.

“Our aim is to understand as much as possible about the high-pressure phase of water, ice VII, so that we can figure out if these planets really can support life and what the limits of habitability might be,” Belof said.

Scientists Create Rare Fifth Form of Matter in Space for the First Time Ever (https://www.livescience.com/63999-fifth-form-of-matter-created.html)

Quote
For a few minutes on Jan. 23, 2017, the coldest spot in the known universe was a tiny microchip hovering 150 miles over Kiruna, Sweden.

The chip was small — about the size of a postage stamp — and loaded with thousands of tightly-packed rubidium-87 atoms. Scientists launched that chip into space aboard an unpiloted, 40-foot-long (12 meters) rocket, then bombarded it with lasers until the atoms inside it cooled to minus 459.67 degrees Fahrenheit (minus 273.15 degrees Celsius) — a fraction of a fraction of a degree above absolute zero, the coldest possible temperature in nature.

While the rocket bobbed in low gravity for the following 6 minutes, scientists were given a rare opportunity to study in-depth the weirdest, least-understood state of matter in the universe — the Bose-Einstein condensate. For the first time ever, scientists had created one in space.

Quote
That brings us back to our rocket, and our very cold chip. When the chip-full-of-atoms was launched into space last January as part of the Matter-Wave Interferometry in Microgravity (MAIUS 1) experiment, scientists on the ground knew they had a few precious minutes to study it once the atoms inside froze. Using a compact laboratory built into the rocket, the team ran 110 lickety-split experiments on the chip to better understand how gravity affects atom trapping and cooling, and how Bose-Einstein condensates behave in free fall.

Among their results published in the Oct. 17 edition of the journal Nature, the researchers found that slicing up and reassembling Bose-Einstein condensates could be a key tool in detecting elusive gravitational waves. In one experiment, the team sliced their condensate cloud in half with a laser, then watched the halves recombine. Because both halves of the cloud share the exact same quantum state and move as a continuous wave, any differences in the two halves after recombination could indicate that an external influence altered that state. According to the researchers, the presence of gravitational waves could be one such influence.
Title: Re: Astronomy Thread
Post by: Star One on 11/06/2018 07:39 pm
Johns Hopkins scientist finds elusive star with origins close to Big Bang (https://hub.jhu.edu/2018/11/05/scientists-find-star-with-big-bang-origins/)

Astronomers at Johns Hopkins University have found what could be one of the universe's oldest stars, a body almost entirely made of materials spewed from the Big Bang.
The discovery of this approximately 13.5 billion-year-old tiny star means more stars with very low mass and very low metal content are likely out there—perhaps even some of the universe's very first stars.
The star is unusual because, unlike other stars with very low metal content, it is part of the Milky Way's "thin disk"—the part of the galaxy in which our own sun resides.
And because this star is so old, researchers say it's possible that our galactic neighborhood is at least 3 billion years older than previously thought.
"This star is maybe one in 10 million," said Kevin Schlaufman, an assistant professor of physics and astronomy and lead author of the study, which is published in The Astrophysical Journal. "It tells us something very important about the first generations of stars."
The universe's first stars after the Big Bang would have consisted entirely of elements like hydrogen, helium, and small amounts of lithium. Those stars then produced elements heavier than helium in their cores and seeded the universe with them when they exploded as supernovae.

The newly discovered star system orbits the galaxy on a circular orbit that, like the orbit of the sun, never gets too far from the plane of the galaxy. On the other hand, most ultra metal-poor stars have orbits that take them across the galaxy and far from its plane.
The next generation of stars formed from clouds of material laced with those metals, incorporating them into their makeup. The metal content, or metallicity, of stars in the universe increased as the cycle of star birth and death continued.
The newly discovered star's extremely low metallicity indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang. Indeed, it is the new record holder for the star with the smallest complement of heavy elements—it has about the same heavy element content as the planet Mercury. In contrast, our sun is thousands of generations down that line and has a heavy element content equal to 14 Jupiters.
Astronomers have found around 30 ancient "ultra metal-poor" stars with the approximate mass of the sun. The star Schlaufman and his team found, however, is only 14 percent the mass of the sun.
The star is part of a two-star system orbiting around a common point. The team found the tiny, almost invisibly faint "secondary" star after another group of astronomers discovered the much brighter "primary" star. That team measured the primary's composition by studying a high-resolution optical spectrum of its light. The presence or absence of dark lines in a star's spectrum can identify the elements it contains, such as carbon, oxygen, hydrogen, iron, and more. In this case, the star had extremely low metallicity. Those astronomers also identified unusual behavior in the star system that implied the presence of a neutron star or black hole. Schlaufman and his team found that to be incorrect, but in doing so, they discovered the visible star's much smaller companion.
The existence of the smaller companion star turned out to be the big discovery. Schlaufman's team was able to infer its mass by studying the primary star's slight "wobble" as the little star's gravity tugged at it.
As recently as the late 1990s, researchers believed that only massive stars could have formed in the earliest stages of the universe—and that they could never be observed because they burn through their fuel and die so quickly.
But as astronomical simulations became more sophisticated, they began to hint that in certain situations, a star from this time period with particularly low mass could still exist, even more than 13 billion years since the Big Bang. Unlike huge stars, low-mass ones can live for exceedingly long times. Red dwarf stars, for instance, with a fraction of the mass of the sun, are thought to live to trillions of years.
The discovery of this new ultra metal-poor star, named 2MASS J18082002–5104378 B, opens up the possibility of observing even older stars.
"If our inference is correct, then low-mass stars that have a composition exclusively the outcome of the Big Bang can exist," said Schlaufman, who is also affiliated with the university's Institute for Data Intensive Engineering and Science. "Even though we have not yet found an object like that in our galaxy, it can exist."
Title: Re: Astronomy Thread
Post by: Star One on 11/06/2018 08:17 pm
 ALMA and MUSE Detect Galactic Fountain (https://www.eso.org/public/news/eso1836/)

Observations by ALMA and data from the MUSE spectrograph on ESO’s VLT have revealed a colossal fountain of molecular gas powered by a black hole in the brightest galaxy of the Abell 2597 cluster — the full galactic cycle of inflow and outflow powering this vast cosmic fountain has never before been observed in one system.

A mere one billion light-years away in the nearby galaxy cluster known as Abell 2597, there lies a gargantuan galactic fountain. A massive black hole at the heart of a distant galaxy has been observed pumping a vast spout of cold molecular gas into space, which then rains back onto the black hole as an intergalactic deluge. The in- and outflow of such a vast cosmic fountain has never before been observed in combination, and has its origin in the innermost 100 000 light-years of the brightest galaxy in the Abell 2597 cluster.

“This is possibly the first system in which we find clear evidence for both cold molecular gas inflow toward the black hole and outflow or uplift from the jets that the black hole launches,” explained Grant Tremblay of the Harvard-Smithsonian Center for Astrophysics and former ESO Fellow, who led this study. “The supermassive black hole at the centre of this giant galaxy acts like a mechanical pump in a fountain.”

Tremblay and his team used ALMA to track the position and motion of molecules of carbon monoxide within the nebula. These cold molecules, with temperatures as low as minus 250–260°C, were found to be falling inwards to the black hole. The team also used data from the MUSE instrument on ESO’s Very Large Telescope to track warmer gas — which is being launched out of the black hole in the form of jets.

“The unique aspect here is a very detailed coupled analysis of the source using data from ALMA and MUSE,” Tremblay explained. “The two facilities make for an incredibly powerful combination.”

Together these two sets of data form a complete picture of the process; cold gas falls towards the black hole, igniting the black hole and causing it to launch fast-moving jets of incandescent plasma into the void. These jets then spout from the black hole in a spectacular galactic fountain. With no hope of escaping the galaxy’s gravitational clutches, the plasma cools off, slows down, and eventually rains back down on the black hole, where the cycle begins anew.

This unprecedented observation could shed light on the life cycle of galaxies. The team speculates that this process may be not only common, but also essential to understanding galaxy formation. While the inflow and outflow of cold molecular gas have both previously been detected, this is the first time both have been detected within one system, and hence the first evidence that the two make up part of the same vast process.

Abell 2597 is found in the constellation Aquarius, and is named for its inclusion in the Abell catalogue of rich clusters of galaxies. The catalogue also includes such clusters as the Fornax cluster, the Hercules cluster, and Pandora’s cluster.
Title: Re: Astronomy Thread
Post by: Star One on 11/07/2018 05:59 pm
Holy Cow! Astronomers Agog at Mysterious New Supernova (https://www.scientificamerican.com/article/holy-cow-astronomers-agog-at-mysterious-new-supernova/)

Quote
For many astronomers, 2018 will be remembered as the Year of the Cow—after the nickname of a spectacular stellar explosion that has kept them busy for months.
The unusual event has offered an unprecedented window on to the collapse of a star, two teams of researchers suggest in papers submitted to the arXiv preprint server on 25 October.
Contrary to the slow ramp-up of a typical supernova, Cow became stupendously bright essentially overnight, leaving astronomers perplexed.
Title: Re: Astronomy Thread
Post by: Zed_Noir on 11/08/2018 07:15 am
Holy Cow! Astronomers Agog at Mysterious New Supernova (https://www.scientificamerican.com/article/holy-cow-astronomers-agog-at-mysterious-new-supernova/)

Quote
For many astronomers, 2018 will be remembered as the Year of the Cow—after the nickname of a spectacular stellar explosion that has kept them busy for months.
The unusual event has offered an unprecedented window on to the collapse of a star, two teams of researchers suggest in papers submitted to the arXiv preprint server on 25 October.
Contrary to the slow ramp-up of a typical supernova, Cow became stupendously bright essentially overnight, leaving astronomers perplexed.

:)
Somewhat semi-serious. Does this look like the effects of a Star disruption weapon from sci-fi lore of the Lensmen series of books. Something that generates a black hole close enough to a star to cause that Star to more or less to be undone.
:)
Title: Re: Astronomy Thread
Post by: Star One on 11/08/2018 10:13 pm
Quote
We report the discovery of VVV-WIT-07, an unique and intriguing variable source presenting a sequence of recurrent dips with a likely deep eclipse in July 2012. The object was found serendipitously in the near-IR data obtained by the VISTA Variables in the V\’ia L\’actea (VVV) ESO Public Survey. Our analysis is based on VVV variability, multicolor, and proper motion (PM) data. Complementary data from the VVV eXtended survey (VVVX) as well as archive data and spectroscopic follow-up observations aided in the analysis and interpretation of VVV-WIT-07. A search for periodicity in the VVV Ks-band light curve of VVV-WIT-07 results in two tentative periods at P~322 days and P~170 days. Colors and PM are consistent either with a reddened MS star or a pre-MS star in the foreground disk. The near-IR spectra of VVV-WIT-07 appear featureless, having no prominent lines in emission or absorption. Features found in the light curve of VVV-WIT-07 are similar to those seen in J1407 (Mamajek’s object), a pre-MS K5 dwarf with a ring system eclipsing the star or, alternatively, to KIC 8462852 (Boyajian’s star), an F3 IV/V star showing irregular and aperiodic dips in its light curve. Alternative scenarios, none of which is fully consistent with the available data, are also briefly discussed, including a young stellar object, a T Tauri star surrounded by clumpy dust structure, a main sequence star eclipsed by a nearby extended object, a self-eclipsing R CrB variable star, and even a long-period, high-inclination X-ray binary.

http://arxiver.moonhats.com/2018/11/07/vvv-wit-07-another-boyajians-star-or-a-mamajeks-object-ssa/
Title: Re: Astronomy Thread
Post by: Star One on 11/09/2018 09:32 am
Planet formation theories predict the existence of free-floating planets, ejected from their parent systems. Although they emit little or no light, they can be detected during gravitational microlensing events. Microlensing events caused by rogue planets are characterized by very short timescales tE (typically below two days) and small angular Einstein radii θE (up to several uas). Here we present the discovery and characterization of two free-floating planet candidates identified in data from the Optical Gravitational Lensing Experiment (OGLE) survey. OGLE-2012-BLG-1323 is one of the shortest events discovered thus far (tE=0.155 +/- 0.005 d, θE=2.37 +/- 0.10 uas) and was caused by an Earth-mass object in the Galactic disk or a Neptune-mass planet in the Galactic bulge. OGLE-2017-BLG-0560 (tE=0.905 +/- 0.005 d, θE=38.7 +/- 1.6 uas) was caused by a Jupiter-mass planet in the Galactic disk or a brown dwarf in the bulge. We rule out stellar companions up to the distance of 6.0 and 3.9 au, respectively. We suggest that the lensing objects, whether located on very wide orbits or free-floating, may originate from the same physical mechanism. Although the sample of ultrashort microlensing events is small, these detections are consistent with low-mass wide-orbit or unbound planets being more common than stars in the Milky Way.

https://arxiv.org/abs/1811.00441
Title: Re: Astronomy Thread
Post by: SciNews on 11/12/2018 07:46 am
Exoplanet Beta Pictoris b orbiting its star
https://www.youtube.com/watch?v=8oebhE6xP4I
Title: Re: Astronomy Thread
Post by: Star One on 11/14/2018 07:56 pm
 Astronomers Discover Second-Closest Known Exoplanet (https://www.smithsonianmag.com/science-nature/astronomers-discover-second-closest-exoplanet-180970818/)

A frozen super earth around Barnard’s star six light years away.

Quote
And the researchers also found something else in the data: faint evidence of another planet, which would be known as Barnard’s Star c. This ghostly second planet in the system, if it exists, is estimated to have a long orbital period and about the mass of Neptune. The existence of the gas planet is even harder to prove, as its 10-year period means it produces a weaker signal. It is worth noting, however, that the measurements place the planet at a similar period to van de Kamp’s claims in the 1960s.

Quote
The new signal, on the other hand, seems to indicate something about 15 Earth-masses, which is unlikely to show a noticeable astrometric signal from Earth. (The new paper mentions that Gaia, a space-based astrometry observatory, might be able to confirm the planet.) Because of its size, the planet makes about a 3 to 4 meter per second radial velocity change—stronger than the other planetary candidate, but without the sheer number of observations to rule out an alternate explanation.

Accompanying ESO video.

https://www.youtube.com/watch?v=UpIxRR99Veo (https://www.youtube.com/watch?v=UpIxRR99Veo)

Here’s the related paper.

https://www.nature.com/articles/s41586-018-0677-y.epdf (https://www.nature.com/articles/s41586-018-0677-y.epdf)
Title: Re: Astronomy Thread
Post by: Star One on 11/15/2018 04:41 pm
A set of videos from ESO.

Barnard’s Star in the solar neighbourhood.

https://youtu.be/SaZKUz4K4tc

Exploring the surface of a super-Earth orbiting Barnard’s Star

https://youtu.be/7MPAHjU7CB8

Artist’s impression of Barnard’s Star and its super-Earth

https://youtu.be/Emxf58tpr3o
Title: Re: Astronomy Thread
Post by: SciNews on 11/15/2018 07:15 pm
Video content provided by the researchers
https://www.youtube.com/watch?v=7X46FxAfhaE
Title: Re: Astronomy Thread
Post by: Star One on 11/15/2018 08:20 pm
eso1837 — Science Release
Super-Earth Orbiting Barnard’s Star
Red Dots campaign uncovers compelling evidence of exoplanet around closest single star to Sun
14 November 2018
The nearest single star to the Sun hosts an exoplanet at least 3.2 times as massive as Earth — a so-called super-Earth. One of the largest observing campaigns to date using data from a world-wide array of telescopes, including ESO’s planet-hunting HARPS instrument, have revealed this frozen, dimly lit world. The newly discovered planet is the second-closest known exoplanet to the Earth. Barnard’s star is the fastest moving star in the night sky.

A planet has been detected orbiting Barnard’s Star, a mere 6 light-years away. This breakthrough — announced in a paper published today in the journal Nature — is a result of the Red Dots and CARMENES projects, whose search for local rocky planets has already uncovered a new world orbiting our nearest neighbour, Proxima Centauri.

The planet, designated Barnard's Star b, now steps in as the second-closest known exoplanet to Earth [1]. The gathered data indicate that the planet could be a super-Earth, having a mass at least 3.2 times that of the Earth, which orbits its host star in roughly 233 days. Barnard’s Star, the planet’s host star, is a red dwarf, a cool, low-mass star, which only dimly illuminates this newly-discovered world. Light from Barnard’s Star provides its planet with only 2% of the energy the Earth receives from the Sun.

Despite being relatively close to its parent star — at a distance only 0.4 times that between Earth and the Sun — the exoplanet lies close to the snow line, the region where volatile compounds such as water can condense into solid ice. This freezing, shadowy world could have a temperature of –170 ℃, making it inhospitable for life as we know it.

Named for astronomer E. E. Barnard, Barnard’s Star is the closest single star to the Sun. While the star itself is ancient — probably twice the age of our Sun — and relatively inactive, it also has the fastest apparent motion of any star in the night sky [2]. Super-Earths are the most common type of planet to form around low-mass stars such as Barnard’s Star, lending credibility to this newly discovered planetary candidate. Furthermore, current theories of planetary formation predict that the snow line is the ideal location for such planets to form.

Previous searches for a planet around Barnard’s Star have had disappointing results — this recent breakthrough was possible only by combining measurements from several high-precision instruments mounted on telescopes all over the world [3].

“After a very careful analysis, we are 99% confident that the planet is there,” stated the team’s lead scientist, Ignasi Ribas (Institute of Space Studies of Catalonia and the Institute of Space Sciences, CSIC in Spain). “However, we’ll continue to observe this fast-moving star to exclude possible, but improbable, natural variations of the stellar brightness which could masquerade as a planet.”

Among the instruments used were ESO’s famous planet-hunting HARPS and UVES spectrographs. “HARPS played a vital part in this project. We combined archival data from other teams with new, overlapping, measurements of Barnard’s star from different facilities,” commented Guillem Anglada Escudé (Queen Mary University of London), co-lead scientist of the team behind this result [4]. “The combination of instruments was key to allowing us to cross-check our result.”

The astronomers used the Doppler effect to find the exoplanet candidate. While the planet orbits the star, its gravitational pull causes the star to wobble. When the star moves away from the Earth, its spectrum redshifts; that is, it moves towards longer wavelengths. Similarly, starlight is shifted towards shorter, bluer, wavelengths when the star moves towards Earth.

Astronomers take advantage of this effect to measure the changes in a star’s velocity due to an orbiting exoplanet — with astounding accuracy. HARPS can detect changes in the star’s velocity as small as 3.5 km/h — about walking pace. This approach to exoplanet hunting is known as the radial velocity method, and has never before been used to detect a similar super-Earth type exoplanet in such a large orbit around its star.

“We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive datasets ever used for precise radial velocity studies.” explained Ribas. ”The combination of all data led to a total of 771 measurements — a huge amount of information!”

“We have all worked very hard on this breakthrough,” concluded Anglada-Escudé. “This discovery is the result of a large collaboration organised in the context of the Red Dots project, that included contributions from teams all over the world. Follow-up observations are already underway at different observatories worldwide.”

https://www.eso.org/public/news/eso1837/

Here’s the related paper.

https://www.eso.org/public/archives/releases/sciencepapers/eso1837/eso1837a.pdf
Title: Re: Astronomy Thread
Post by: Star One on 11/15/2018 09:02 pm
 International Team, NASA Make Unexpected Discovery Under Greenland Ice (https://www.nasa.gov/press-release/international-team-nasa-make-unexpected-discovery-under-greenland-ice)

https://youtu.be/vTr3VdGlFr8

An international team of researchers, including a NASA glaciologist, has discovered a large meteorite impact crater hiding beneath more than a half-mile of ice in northwest Greenland. The crater — the first of any size found under the Greenland ice sheet — is one of the 25 largest impact craters on Earth, measuring roughly 1,000 feet deep and more than 19 miles in diameter, an area slightly larger than that inside Washington’s Capital Beltway.

The group, led by researchers from the University of Copenhagen’s Centre for GeoGenetics at the Natural History Museum of Denmark worked for the past three years to verify their discovery, which they initially made in 2015 using NASA data. Their finding is published in the Nov. 14 issue of the journal Science Advances.

"NASA makes the data it collects freely available to scientists and the public all around the world,” said Joe MacGregor, a NASA glaciologist at Goddard Space Flight Center in Greenbelt, Maryland, who became involved in the investigation in its early stages. “That set the stage for our Danish colleagues’ ‘Eureka’ moment."

The researchers first spotted the crater in July 2015, while they were inspecting a new map of the topography beneath Greenland's ice sheet that used ice-penetrating radar data primarily from NASA’s Operation IceBridge — a multi-year airborne mission to track changes in polar ice — and earlier NASA airborne missions in Greenland. The scientists noticed an enormous, previously unexamined circular depression under Hiawatha Glacier, sitting at the very edge of the ice sheet in northwestern Greenland.

Using satellite imagery from the Moderate Resolution Imaging Spectroradiometer instrument on NASA’s Terra and Aqua satellites, MacGregor also examined the surface of the ice in the Hiawatha Glacier region and quickly found evidence of a circular pattern on the ice surface that matched the one observed in the bed topography map.

To confirm their suspicions, in May 2016 the team sent a research plane from Germany’s Alfred Wegener Institute to fly over the Hiawatha Glacier and map the crater and the overlying ice with a state-of-the-art ice-penetrating radar provided by the University of Kansas. MacGregor, who is an expert in radar measurements of ice, helped design the airborne survey.

"Previous radar measurements of Hiawatha Glacier were part of a long-term NASA effort to map Greenland’s changing ice cover," MacGregor said. "What we really needed to test our hypothesis was a dense and focused radar survey there. The survey exceeded all expectations and imaged the depression in stunning detail: a distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris — it’s all there."

The crater formed less than 3 million years ago, according to the study, when an iron meteorite more than half a mile wide smashed into northwest Greenland. The resulting depression was subsequently covered by ice.

"The crater is exceptionally well-preserved and that is surprising because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact," said Kurt Kjær, a professor at the Center for GeoGenetics at the Natural History Museum of Denmark and lead author of the study.

Kjær said that the crater’s condition indicates the impact might even have occurred toward the end of the last ice age, which would place the resulting crater among the youngest on the planet.

In the summers of 2016 and 2017, the research team returned to the Hiawatha Glacier to map tectonic structures in the rock near the foot of the glacier and collect samples of sediments washed out from the depression through a meltwater channel.

"Some of the quartz sand coming from the crater had planar deformation features indicative of a violent impact; this is conclusive evidence that the depression beneath the Hiawatha Glacier is a meteorite crater," said associate professor Nicolaj Larsen of Aarhus University in Denmark, one of the authors of the study..

Earlier studies have shown large impacts can profoundly affect Earth’s climate, with major consequences for life on Earth at the time. The researchers plan to continue their work in this area, addressing remaining questions on when and how the meteorite impact at Hiawatha Glacier affected the planet.

For more on NASA’s Earth science activities, visit:

https://www.nasa.gov/earth
Title: Astronomy Thread
Post by: Star One on 11/19/2018 04:34 pm
ESOcast 185 Light: Cosmic Serpent

https://www.youtube.com/watch?v=m9CW47B2pOE

Zooming in on Apep

https://youtu.be/CqTWI-qCP44
Title: Astronomy Thread
Post by: Star One on 11/21/2018 05:54 am
Newly Discovered Planet Could Have Habitable Atmosphere, Suggests New Study (https://www.inverse.com/article/51083-scientists-identify-trappist-1e-climate-as-habitable)

Quote
Research published this month in the Astrophysical Journal shows radiation and chemistry models detailing the different atmospheres of TRAPPIST-1’s seven Earth-sized planets, and one of them, TRAPPIST-1 e, is the planet that might be just right for humans one day, assuming they can safely make the 39-light-year journey to the star system.
Title: Re: Astronomy Thread
Post by: Star One on 11/21/2018 12:07 pm
 Beddgelert meteorite: big find in a small village (http://m.skyatnightmagazine.com/news/beddgelert-meteorite-big-find-small-village)

Quote
The residents of Beddgelert in North Wales were surprised when, one day in 1949, a meteorite crashed through the roof of a local hotel. The event has gone down in local history.

Katrin Raynor Evans, librarian at Cardiff Astronomical Society, reveals the story of the Beddgelert meteorite.



Title: Re: Astronomy Thread
Post by: Star One on 11/22/2018 08:34 pm
How Much SETI Has Been Done? Finding Needles in the n-Dimensional Cosmic Haystack (https://arxiv.org/abs/1809.07252)

Quote
Many articulations of the Fermi Paradox have as a premise, implicitly or explicitly, that humanity has searched for signs of extraterrestrial radio transmissions and concluded that there are few or no obvious ones to be found. Tarter et al. (2010) and others have argued strongly to the contrary: bright and obvious radio beacons might be quite common in the sky, but we would not know it yet because our search completeness to date is so low, akin to having searched a drinking glass's worth of seawater for evidence of fish in all of Earth's oceans. Here, we develop the metaphor of the multidimensional "Cosmic Haystack" through which SETI hunts for alien "needles" into a quantitative, eight-dimensional model and perform an analytic integral to compute the fraction of this haystack that several large radio SETI programs have collectively examined. Although this model haystack has many qualitative differences from the Tarter et al. (2010) haystack, we conclude that the fraction of it searched to date is also very small: similar to the ratio of the volume of a large hot tub or small swimming pool to that of the Earth's oceans. With this article we provide a Python script to calculate haystack volumes for future searches and for similar haystacks with different boundaries. We hope this formalism will aid in the development of a common parameter space for the computation of upper limits and completeness fractions of search programs for radio and other technosignatures.
Title: Re: Astronomy Thread
Post by: Star One on 11/25/2018 09:00 am
VVV-WIT-07: another Boyajian's star or a Mamajek's object?

Quote
We report the discovery of VVV-WIT-07, an unique and intriguing variable source presenting a sequence of recurrent dips with a likely deep eclipse in July 2012. The object was found serendipitously in the near-IR data obtained by the VISTA Variables in the Vía Láctea (VVV) ESO Public Survey. Our analysis is based on VVV variability, multicolor, and proper motion (PM) data. Complementary data from the VVV eXtended survey (VVVX) as well as archive data and spectroscopic follow-up observations aided in the analysis and interpretation of VVV-WIT-07. A search for periodicity in the VVV Ks-band light curve of VVV-WIT-07 results in two tentative periods at P~322 days and P~170 days. Colors and PM are consistent either with a reddened MS star or a pre-MS star in the foreground disk. The near-IR spectra of VVV-WIT-07 appear featureless, having no prominent lines in emission or absorption. Features found in the light curve of VVV-WIT-07 are similar to those seen in J1407 (Mamajek's object), a pre-MS K5 dwarf with a ring system eclipsing the star or, alternatively, to KIC 8462852 (Boyajian's star), an F3 IV/V star showing irregular and aperiodic dips in its light curve. Alternative scenarios, none of which is fully consistent with the available data, are also briefly discussed, including a young stellar object, a T Tauri star surrounded by clumpy dust structure, a main sequence star eclipsed by a nearby extended object, a self-eclipsing R CrB variable star, and even a long-period, high-inclination X-ray binary.

https://arxiv.org/abs/1811.02265
Title: Astronomy Thread
Post by: Star One on 11/29/2018 08:30 pm
Prehistoric cave art reveals ancient use of complex astronomy (https://eurekalert.org/pub_releases/2018-11/uoe-pca112718.php)

Quote
Some of the world's oldest cave paintings have revealed how ancient people had relatively advanced knowledge of astronomy.

The artworks, at sites across Europe, are not simply depictions of wild animals, as was previously thought. Instead, the animal symbols represent star constellations in the night sky, and are used to represent dates and mark events such as comet strikes, analysis suggests.

They reveal that, perhaps as far back as 40,000 years ago, humans kept track of time using knowledge of how the position of the stars slowly changes over thousands of years.

The findings suggest that ancient people understood an effect caused by the gradual shift of Earth's rotational axis. Discovery of this phenomenon, called precession of the equinoxes, was previously credited to the ancient Greeks.

Quote
Dr Martin Sweatman, of the University of Edinburgh's School of Engineering, who led the study, said: "Early cave art shows that people had advanced knowledge of the night sky within the last ice age. Intellectually, they were hardly any different to us today.

"These findings support a theory of multiple comet impacts over the course of human development, and will probably revolutionise how prehistoric populations are seen."

 What happens when materials take tiny hits (http://news.mit.edu/2018/microscopic-materials-take-tiny-hits-1129)

Quote
When tiny particles strike a metal surface at high speed — for example, as coatings being sprayed or as micrometeorites pummeling a space station — the moment of impact happens so fast that the details of process haven’t been clearly understood, until now.
A team of researchers at MIT has just accomplished the first detailed high-speed imaging and analysis of the microparticle impact process, and used that data to predict when the particles will bounce away, stick, or knock material off the surface and weaken it. The new findings are described in a paper appearing today in the journal Nature Communications.
Title: Re: Astronomy Thread
Post by: leovinus on 11/29/2018 08:47 pm
StarOne, just so you know, this thread and your efforts are very much appreciated! For Astronomy, I follow this daily, as well as Astro Blogs (http://www.astroblogs.nl).
Title: Re: Astronomy Thread
Post by: Star One on 11/29/2018 08:51 pm
StarOne, just so you know, this thread and your efforts are very much appreciated! For Astronomy, I follow this daily, as well as Astro Blogs (http://www.astroblogs.nl).

Thank you. I know that MIT press release above isn’t really astronomy but I couldn’t think where else to put it and it’s not worth its own thread.
Title: Re: Astronomy Thread
Post by: as58 on 11/29/2018 09:16 pm
Prehistoric cave art reveals ancient use of complex astronomy (https://eurekalert.org/pub_releases/2018-11/uoe-pca112718.php)

Quote
Some of the world's oldest cave paintings have revealed how ancient people had relatively advanced knowledge of astronomy.

The artworks, at sites across Europe, are not simply depictions of wild animals, as was previously thought. Instead, the animal symbols represent star constellations in the night sky, and are used to represent dates and mark events such as comet strikes, analysis suggests.

They reveal that, perhaps as far back as 40,000 years ago, humans kept track of time using knowledge of how the position of the stars slowly changes over thousands of years.

The findings suggest that ancient people understood an effect caused by the gradual shift of Earth's rotational axis. Discovery of this phenomenon, called precession of the equinoxes, was previously credited to the ancient Greeks.

Quote
Dr Martin Sweatman, of the University of Edinburgh's School of Engineering, who led the study, said: "Early cave art shows that people had advanced knowledge of the night sky within the last ice age. Intellectually, they were hardly any different to us today.

"These findings support a theory of multiple comet impacts over the course of human development, and will probably revolutionise how prehistoric populations are seen."

I haven't read the actual article, but the press release doesn't sound very credible.
Title: Astronomy Thread
Post by: Star One on 12/01/2018 08:40 am
 Astronomers Are Tracking Four Potential Interstellar Objects Now In Our Outer Solar System (https://www.forbes.com/sites/brucedorminey/2018/11/30/astronomers-are-tracking-4-potential-interstellar-objects-now-in-our-outer-solar-system/#180067d8b5c3)

Quote
Using detailed computer models of asteroidal-type objects between the Sun and Jupiter, two Harvard University researchers find that at least four known objects are likely to have origins from outside our solar system.
Title: Re: Astronomy Thread
Post by: Star One on 12/04/2018 07:46 am
 Combination of Space-based and Ground-based Telescopes Reveals more than 100 Exoplanets (https://www.nao.ac.jp/en/news/science/2018/20181203-abc.html)

Quote
An international research team involving researchers at the University of Tokyo and Astrobiology Center of the National Institutes of Natural Sciences investigated 227 K2 exoplanet candidates using other space telescopes and ground-based telescopes. They confirmed that 104 of them are really exoplanets. Seven of the confirmed exoplanets have ultra-short orbital periods less than 24 hours. The formation process of exoplanets with such short orbital periods is still unclear. Further study of these ultra-short period planets will help to advance research into the processes behind their formation. They also confirmed many low-mass rocky exoplanets with masses less than twice that of the Earth as well as some planetary systems with multiple exoplanets.
Title: Re: Astronomy Thread
Post by: Star One on 12/07/2018 06:51 am
Ganymede, Jupiter’s largest moon, shows signs of past tectonic activity (https://www.sciencefocus.com/news/ganymede-jupiters-largest-moon-shows-signs-of-past-tectonic-activity/)

Quote
Galileo spacecraft data suggests fault lines that shear against one another horizontally, like the San Andreas fault found in California.
Title: Re: Astronomy Thread
Post by: Star One on 12/08/2018 09:59 am
 Enormous ‘ghost’ galaxy spotted hiding next to the Milky Way (https://www.imperial.ac.uk/news/189023/enormous-ghost-galaxy-spotted-hiding-next/)

Quote
A galaxy a third the size of our own, but extremely faint, has been observed orbiting around the Milky Way.
Title: Re: Astronomy Thread
Post by: Star One on 12/11/2018 10:55 pm
http://news.ku.edu/2018/12/05/researchers-consider-whether-supernovae-killed-large-ocean-animals-dawn-pleistocene

Quote
About 2.6 million years ago, an oddly bright light arrived in the prehistoric sky and lingered there for weeks or months. It was a supernova some 150 light years away from Earth. Within a few hundred years, long after the strange light in the sky had dwindled, a tsunami of cosmic energy from that same shattering star explosion could have reached our planet and pummeled the atmosphere, touching off climate change and triggering mass extinctions of large ocean animals, including a shark species that was the size of a school bus.
Title: Re: Astronomy Thread
Post by: Star One on 12/12/2018 07:03 pm
A batch of new videos from ESO.

https://youtu.be/Op3Y2yHXHNU

https://youtu.be/v_-f3tMVNB8

https://youtu.be/PCsaD-cCcmo

https://youtu.be/pGKp4ccYa2k

https://youtu.be/9otaURdkMos

https://youtu.be/SU1z1VCH06E

https://youtu.be/vbz-0Y_wFFQ

https://youtu.be/B1UwlXyLTAw
Title: Re: Astronomy Thread
Post by: whitelancer64 on 12/12/2018 07:48 pm
Prehistoric cave art reveals ancient use of complex astronomy (https://eurekalert.org/pub_releases/2018-11/uoe-pca112718.php)

Quote
Some of the world's oldest cave paintings have revealed how ancient people had relatively advanced knowledge of astronomy.

The artworks, at sites across Europe, are not simply depictions of wild animals, as was previously thought. Instead, the animal symbols represent star constellations in the night sky, and are used to represent dates and mark events such as comet strikes, analysis suggests.

They reveal that, perhaps as far back as 40,000 years ago, humans kept track of time using knowledge of how the position of the stars slowly changes over thousands of years.

The findings suggest that ancient people understood an effect caused by the gradual shift of Earth's rotational axis. Discovery of this phenomenon, called precession of the equinoxes, was previously credited to the ancient Greeks.

Quote
Dr Martin Sweatman, of the University of Edinburgh's School of Engineering, who led the study, said: "Early cave art shows that people had advanced knowledge of the night sky within the last ice age. Intellectually, they were hardly any different to us today.

"These findings support a theory of multiple comet impacts over the course of human development, and will probably revolutionise how prehistoric populations are seen."

I haven't read the actual article, but the press release doesn't sound very credible.

There's an article with some more detail here:

https://www.universetoday.com/140705/prehistoric-cave-paintings-show-that-ancient-people-had-pretty-advanced-knowledge-of-astronomy/

Apparently, comparing cave paintings and other artwork at several sites indicates some correspond to the constellations as they appeared at the time. That could just be a coincidence, but the dates of the artwork also seem to correspond to known cometary impacts. They conclude the two may be linked, that the art is something like a memorial to major astronomical events.

The general concept that some cave paintings may represent constellations is not a new one.

http://journalofcosmology.com/Consciousness159.html

Some of the evidence is quite strong: one painting of a bull in Lascaux Cave has six dots over one shoulder, to represent the Pleiades, as well as two dots in its head, that may represent stars in the constellation Taurus.

The new paper seems to be presenting the idea that other constellations were also accurately represented and also that they may represent major astronomical events. Fair enough, may be, but I'm less convinced of their idea that this means the prehistoric peoples understood the precession of the equinoxes.
Title: Re: Astronomy Thread
Post by: as58 on 12/13/2018 10:04 am
Apparently, comparing cave paintings and other artwork at several sites indicates some correspond to the constellations as they appeared at the time. That could just be a coincidence, but the dates of the artwork also seem to correspond to known cometary impacts. They conclude the two may be linked, that the art is something
like a memorial to major astronomical events.

The existence of those relatively recent cometary impacts is very much in dispute in the first place. Also, the interpretation of cave paintings as asterisms (which somehow seem to follow closely the modern constellations) seems stretched; the figures in Appendix B aren't convincing.

Not that academic expertise necessarily means anything, but neither of the authors seems to be an astronomer or archaeologist.
Title: Re: Astronomy Thread
Post by: Star One on 12/14/2018 12:16 pm
Video from Cool Worlds about RNAAS banned on ArXiv

https://youtu.be/kj2M_VYWECY
Title: Re: Astronomy Thread
Post by: Star One on 12/16/2018 02:27 pm
 Fireball That Exploded Over Greenland Shook Earth, Triggering Seismic Sensors (https://www.livescience.com/64291-greenland-fireball-seismic-recordings.html)

Quote
When a blazing fireball from space exploded over Earth on July 25, scientists captured the first-ever seismic recordings of a meteor impact on ice in Greenland.

At approximately 8 p.m. local time on that day, residents of the town of Qaanaaq on Greenland's northwestern coast reported seeing a bright light in the sky and feeling the ground shake as a meteor combusted over the nearby Thule Air Base.

But the fleeting event was detected by more than just human observers, according to unpublished research presented Dec. 12 here at the annual conference of the American Geophysical Union (AGU).
Title: Re: Astronomy Thread
Post by: SciNews on 12/17/2018 05:23 pm
2018 VG18 “Farout” the most distant body observed in the Solar System
https://www.youtube.com/watch?v=br1oclqR4EY
Title: Re: Astronomy Thread
Post by: Star One on 12/17/2018 08:18 pm
Here’s the press release from the Carnegie.

 DISCOVERY OF THE MOST DISTANT SOLAR SYSTEM OBJECT EVER OBSERVED (https://sites.google.com/carnegiescience.edu/sheppard/farout)

Quote
A team of astronomers has discovered the most-distant body ever observed in our Solar System.  It is the first known Solar System object that has been detected at a distance that is more than 100 times farther than Earth is from the Sun.
 
The new object was announced on Monday, December 17, 2018 by the International Astronomical Union’s Minor Planet Center and has been given the provisional designation 2018 VG18. The discovery was made by Carnegie’s Scott S. Sheppard, the University of Hawaii’s David Tholen, and Northern Arizona University’s Chad Trujillo.
 
2018 VG18, nicknamed “Farout” by the discovery team for its extremely distant location, is at about 120 astronomical units (AU), where 1 AU is defined as the distance between the Earth and Sun.  The second-most-distant observed Solar System object is Eris, at about 96 AU.  Pluto is currently at about 34 AU, making 2018 VG18 more than three-and-a-half times more distant than the Solar System’s most-famous dwarf planet.
Title: Re: Astronomy Thread
Post by: Star One on 12/17/2018 09:08 pm
Alien Imposters: Planets with Oxygen Don’t Necessarily Have Life (https://releases.jhu.edu/2018/12/17/alien-imposters-planets-with-oxygen-dont-necessarily-have-life/)

In their search for life in solar systems near and far, researchers have often accepted the presence of oxygen in a planet’s atmosphere as the surest sign that life may be present there. A new Johns Hopkins study, however, recommends a reconsideration of that rule of thumb.
Simulating in the lab the atmospheres of planets beyond the solar system, researchers successfully created both organic compounds and oxygen, absent of life.
The findings, published on Dec. 11, 2018, in ACS Earth and Space Chemistry, serve as a cautionary tale for researchers who suggest the presence of oxygen and organics on distant worlds is evidence of life there.
Oxygen makes up 20 percent of Earth’s atmosphere and is considered one of the most robust biosignature gases in Earth’s atmosphere. In the search for life beyond Earth’s solar system, however, little is known about how different energy sources initiate chemical reactions and how those reactions can create biosignatures like oxygen. While other researchers have run photochemical models on computers to predict what exoplanet atmospheres might be able to create, no such simulations to He’s knowledge have before now been conducted in the lab.

Chao He explaining how the study’s PHAZER setup works.
Credit: Chanapa Tantibanchachai
The research team performed the simulation experiments in a specially designed Planetary HAZE (PHAZER) chamber in the lab of Sarah Hörst, assistant professor of Earth and planetary sciences and the paper’s co-author. The researchers tested nine different gas mixtures, consistent with predictions for super-Earth and mini-Neptune type exoplanet atmospheres; such exoplanets are the most abundant type of planet in our Milky Way galaxy. Each mixture had a specific composition of gases such as carbon dioxide, water, ammonia, and methane, and each was heated at temperatures ranging from about 80 to 700 degrees Fahrenheit.
He and the team allowed each gas mixture to flow into the PHAZER setup and then exposed the mixture to one of two types of energy, meant to mimic energy that triggers chemical reactions in planetary atmospheres: plasma from an alternating current glow discharge or light from an ultraviolet lamp. Plasma, an energy source stronger than UV light, can simulate electrical activities like lightning and/or energetic particles, and UV light is the main driver of chemical reactions in planetary atmospheres such as those on Earth, Saturn and Pluto.
After running the experiments continuously for three days, corresponding to the amount of time gas would be exposed to energy sources in space, the researchers measured and identified resulting gasses with a mass spectrometer, an instrument that sorts chemical substances by their mass to charge ratio.

A CO2-rich planetary atmosphere exposed to a plasma discharge in Sarah Hörst’s lab.
Credit: Chao He
The research team found multiple scenarios that produced both oxygen and organic molecules that could build sugars and amino acids—raw materials for which life could begin—such as formaldehyde and hydrogen cyanide.
“People used to suggest that oxygen and organics being present together indicates life, but we produced them abiotically in multiple simulations,” He says. “This suggests that even the co-presence of commonly accepted biosignatures could be a false positive for life.”
This study was funded by the NASA Exoplanets Research Program Grant NNX16AB45G. Chao He received funding from the Morton K. and Jane Blaustein Foundation.
###
Johns Hopkins University news releases are available online, as is information for reporters. To arrange a video or audio interview with a Johns Hopkins expert, contact a media representative listed above or visit our studio web page. Find more Johns Hopkins stories on the Hub.
Title: Astronomy Thread
Post by: Star One on 12/21/2018 08:52 pm
NASA and the Search for Technosignatures: A Report from the NASA Technosignatures Workshop

NASA Technosignatures Workshop Participants
(Submitted on 20 Dec 2018)
This report is the product of the NASA Technosignatures Workshop held at the Lunar and Planetary Institute in Houston, Texas, in September 2018. This workshop was convened by NASA for the organization to learn more about the current field and state of the art of searches for technosignatures, and what role NASA might play in these searches in the future. The report, written by the workshop participants, summarizes the material presented at the workshop and incorporates additional inputs from the participants. Section 1 explains the scope and purpose of the document, provides general background about the search for technosignatures, and gives context for the rest of the report. Section 2 discusses which experiments have occurred, along with current limits on technosignatures. Section 3 addresses the current state of the technosignature field as well as the state-of-the-art for technosignature detection. Section 4 addresses near-term searches for technosignatures, and Section 5 discusses emerging and future opportunities in technosignature detection.

https://arxiv.org/abs/1812.08681

Intermediate Mass Black Holes Discovered in Galactic Nuclei
Friday, December 21, 2018
Science Update - A look at CfA discoveries from recent journals
The existence of black holes is well established, and observations have found both stellar mass sized objects and giant ones millions to billions times more massive than the sun at the centers of galaxies. But the origin of these massive black holes is a mystery. Small black holes are the ashes of supernovae, but massive ones presumably must start small and grow over time. Such growth is highly constrained, however, because the vary act of accreting material generates radiation that inhibits further inflow, and billions of years are thought to be needed to make billion solar-mass black holes. The problem arises because astronomers have now detected quasars with supermassive black holes in the early universe - but there has not been enough time since the big bang for them to grow to supermassive sizes. Stellar mass black holes, furthermore, should have produced many intermediate mass black holes as they grew, yet only a few are candidates and their identification as IMBHs remains controversial. The firm identification of IMBHs could help clarify the issue. An alternative suggestion has been advanced to solve the problem. The direct collapse of a large gas cloud in the early universe could produce an intermediate-sized black hole (IMBH) with hundreds to hundreds of thousands of solar masses, leaving plenty of time for them all to grow by now into supermassive objects.

CfA astronomer Igor Chilingarian led a team that has for the first time identified a set of galaxies with active nuclei hosting intermediate mass black holes. They used optical and near-infrared galaxy surveys to identify candidate sources from the intensity and velocities of their atomic emission lines, selecting three hundred and five likely IMBH candidates. They then obtained X-ray measurements from the Chandra and/or XMM missions which confirmed that ten of these nuclei were IMBHs and were actively accreting. The least massive IMBH they discovered in their set of ten had thirty-six thousand solar-masses; the largest had about ten times more. Their discovery is remarkable not only because it marks the first conclusive detection of these elusive objects, but because it lends credence to the idea that stellar-mass black holes seeded the early universe, with many of them then growing into the supermassive monsters we see today.

Reference(s):
"A Population of Bona Fide Intermediate-mass Black Holes Identified as Low-luminosity Active Galactic Nuclei," Igor V. Chilingarian, Ivan Yu. Katkov, Ivan Yu. Zolotukhin, Kirill A. Grishin, Yuri Beletsky, Konstantina Boutsia, and David J. Osip, ApJ 863, 1 2018.
Title: Astronomy Thread
Post by: Star One on 12/22/2018 09:38 am
Stephen Hawking's Final Theory About Our Universe Will Melt Your Brain (https://www.sciencealert.com/stephen-hawking-s-final-theory-about-our-universe-will-melt-your-brain)

Quote
The paper, published in the Journal of High Energy Physics in May, puts forward that the Universe is far less complex than current multiverse theories suggest.

It's based around a concept called eternal inflation, first introduced in 1979 and published in 1981.
Title: Re: Astronomy Thread
Post by: Star One on 12/27/2018 10:51 pm
A big space crash likely made Uranus lopsided (https://phys.org/news/2018-12-big-space-uranus-lopsided.amp)

Quote
The computer simulations show that the collision and reshaping of Uranus—maybe enveloping some or all of the rock that hit it—happened in a matter of hours, Kegerreis said. He produced an animation showing the violent crash and its aftermath.

It's also possible that the big object that knocked over Uranus is still lurking in the solar system too far for us to see, said Green. It would explain some of the orbits of the planet and fit with a theory that a missing planet X is circling the sun well beyond Pluto, he said.
Title: Re: Astronomy Thread
Post by: Star One on 12/29/2018 07:28 pm
Scientists think they've found a super-Earth exoplanet dripping with sapphires and rubies (https://www.popsci.com/exoplanet-sapphires-rubies)

Quote
And it’s far from the only exoplanet of its kind. Descriptions of previously-discovered super-Earths like 55 Cancri e and WASP-47 e retain the same sort of lighter-than-expected densities that HD219134 b does. As a result of the new findings, the team hypothesizes that “a new class of rocky exoplanets exists made from large quantities of calcium and aluminum and their oxides, and these planets formed very close to their stars,” says Bonsor. 55 Cancri e, WASP-47 e, and HD219134 b are simply the first three candidates of this class.
Title: Re: Astronomy Thread
Post by: Star One on 01/03/2019 06:35 am
Early protostar already has a warped disk (http://www.riken.jp/en/pr/press/2019/20190101_1/)

Quote
Using observations from the ALMA radio observatory in Chile, researchers have observed, for the first time, a warped disk around an infant protostar that formed just several tens of thousands of years ago. This implies that the misalignment of planetary orbits in many planetary systems—including our own—may be caused by distortions in the planet-forming disk early in their existence.
Title: Re: Astronomy Thread
Post by: SciNews on 01/03/2019 07:11 pm
Comets observed in the last 3 days
Comet 64P/Swift-Gehrels https://www.virtualtelescope.eu/2019/01/03/comet-64p-swift-gehrels-an-image-3-jan-2019/
Comet 60P/Tsuchinshan https://www.virtualtelescope.eu/2019/01/02/comet-60p-tsuchinshan-an-image-2-jan-2019/
Comet 46P/Wirtanen https://www.virtualtelescope.eu/2019/01/02/comet-46p-wirtanen-a-new-image-2-jan-2019/
Comet 38P/Stephan-Oterma https://www.virtualtelescope.eu/2019/01/03/comet-38p-stephan-oterma-an-image-1-jan-2019/
Comet 123P/West-Hartley https://www.virtualtelescope.eu/2019/01/03/comet-123p-west-hartley-an-image-2-jan-2019/
Title: Re: Astronomy Thread
Post by: Star One on 01/04/2019 07:38 am
Some shocking reporting on this story I’ve seen, considering it’s not going to happen for another 2.5 billion years it is all a bit silly.

Nearby galaxy set to collide with Milky Way, say scientists (https://www.theguardian.com/science/2019/jan/04/nearby-galaxy-large-magellanic-cloud-set-to-collide-with-milky-way)

Quote
The unfortunate discovery was made after scientists ran computer simulations on the movement of the Large Magellanic Cloud (LMC), one of the many satellite galaxies that orbits the Milky Way. Rather than circling at a safe distance, or breaking free of the Milky Way’s gravitational pull, the researchers found the LMC is destined to clatter into the galaxy we call home.

At the moment, the LMC is estimated to be about 163,000 light years from the Milky Way and speeding away at 250 miles per second. But simulations by astrophysicists at Durham University show that the LMC will eventually slow down and turn back towards us, ultimately smashing into the Milky Way in about 2.5 billion years’ time.
Title: Astronomy Thread
Post by: Star One on 01/06/2019 11:35 am
Tiny satellites could be “guide stars” for huge next-generation telescopes (http://news.mit.edu/2019/tiny-satellites-guide-telescopes-0104)

Quote
Researchers design CubeSats with lasers to provide steady reference light for telescopes investigating distant planets.

Our universe: An expanding bubble in an extra dimension (https://www.eurekalert.org/pub_releases/2018-12/uu-oua122818.php)

Quote
Uppsala University researchers have devised a new model for the Universe - one that may solve the enigma of dark energy. Their new article, published in Physical Review Letters, proposes a new structural concept, including dark energy, for a universe that rides on an expanding bubble in an additional dimension.

SPACE AND TIME COULD BE A QUANTUM ERROR-CORRECTING CODE (https://www.wired.com/story/space-and-time-could-be-a-quantum-error-correcting-code/)
Title: Re: Astronomy Thread
Post by: SciNews on 01/06/2019 01:48 pm
Partial Solar Eclipse in China, 6 January 2019
https://www.youtube.com/watch?v=pCLvpZ71uFo
Title: Re: Astronomy Thread
Post by: Star One on 01/06/2019 07:14 pm
Our universe has antimatter partner on the other side of the Big Bang, say physicists (https://physicsworld.com/a/our-universe-has-antimatter-partner-on-the-other-side-of-the-big-bang-say-physicists/)

Quote
Our universe could be the mirror image of an antimatter universe extending backwards in time before the Big Bang. So claim physicists in Canada, who have devised a new cosmological model positing the existence of an “antiuniverse” which, paired to our own, preserves a fundamental rule of physics called CPT symmetry. The researchers still need to work out many details of their theory, but they say it naturally explains the existence of dark matter.

Title: Re: Astronomy Thread
Post by: Star One on 01/07/2019 07:31 pm
Discovery Announcement of Binary System 2016 AZ8 (http://www.naic.edu/~pradar/press/2016AZ8.php)

Quote
Discovery Announcement of Binary System Near-Earth Asteroid 2016 AZ8
A. K. Virkki, S. E. Marshall, F. C. F. Venditti, L. F. Zambrano Marin, Arecibo Observatory, University of Central Florida, and E. G. Rivera-Valentin, P. A. Taylor, Lunar and Planetary Institute, Universities Space Research Association, report that Arecibo (2380 MHz, 12.6 cm) range-Doppler radar images obtained on 2019 January 4.72 UT reveal near-Earth asteroid 2016 AZ8 is a binary system. Preliminary measurements of visible range extents in radar images with 7.5 m/pixel resolution suggest a rounded primary of diameter 420 ± 60 m and an elongated secondary 180 ± 30 m long. This implies a visual albedo of 4 ± 1% for an absolute magnitude of 21.0. The system was observed near maximum range separation along the line of sight at 420 ± 45 m, which is a lower bound on the mutual-orbit scale due to possible projection effects. Echo bandwidths place upper bounds on the rotation periods of the primary and secondary of 7 and 40 hours, also subject to projection effects. Further observations are encouraged; no more radar observations from Arecibo are possible this apparition. A projected separation comparable to the primary diameter and the slow projected rotation periods suggest the mutual-orbit plane of the system may have been inclined by tens of degrees relative to the line of sight during the observations. As such, observers should assume typical parameters for near-Earth binary systems of 2 to 4 hours for the primary rotation period and a mutual-orbit period between 12 and 24 hours.
Title: Re: Astronomy Thread
Post by: SciNews on 01/08/2019 05:41 pm
Bevy of mysterious fast radio bursts spotted by Canadian telescope
https://www.nature.com/articles/d41586-019-00049-5
Research papers will be available tomorrow.
Title: Re: Astronomy Thread
Post by: Star One on 01/08/2019 08:59 pm
Bevy of mysterious fast radio bursts spotted by Canadian telescope
https://www.nature.com/articles/d41586-019-00049-5
Research papers will be available tomorrow.

Carlo Rovelli in a recent New Scientist article proposed that FRBs could in fact be white holes.

https://www.newscientist.com/article/mg24032080-100-if-you-think-black-holes-are-strange-white-holes-will-blow-your-mind/
Title: Astronomy Thread
Post by: Star One on 01/09/2019 08:13 pm
Core crystallization and pile-up in the cooling sequence of evolving white dwarfs (https://www.nature.com/articles/s41586-018-0791-x)

White dwarfs are stellar embers depleted of nuclear energy sources that cool over billions of years1. These stars, which are supported by electron degeneracy pressure, reach densities of 107 grams per cubic centimetre in their cores2. It has been predicted that a first-order phase transition occurs during white-dwarf cooling, leading to the crystallization of the non-degenerate carbon and oxygen ions in the core, which releases a considerable amount of latent heat and delays the cooling process by about one billion years3. However, no direct observational evidence of this effect has been reported so far. Here we report the presence of a pile-up in the cooling sequence of evolving white dwarfs within 100 parsecs of the Sun, determined using photometry and parallax data from the Gaia satellite4. Using modelling, we infer that this pile-up arises from the release of latent heat as the cores of the white dwarfs crystallize. In addition to the release of latent heat, we find strong evidence that cooling is further slowed by the liberation of gravitational energy from element sedimentation in the crystallizing cores5,6,7. Our results describe the energy released by crystallization in strongly coupled Coulomb plasmas8,9, and the measured cooling delays could help to improve the accuracy of methods used to determine the age of stellar populations from white dwarfs10.

The corona contracts in a black-hole transient (https://www.nature.com/articles/s41586-018-0803-x)

The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months1,2,3. When a black hole emerges from quiescence (that is, it ‘turns on’ after accreting material from its companion) it has a very hard (high-energy) X-ray spectrum produced by a hot corona4,5 positioned above its accretion disk, and then transitions to a soft (lower-energy) spectrum dominated by emission from the geometrically thin accretion disk, which extends to the innermost stable circular orbit6,7. Much debate persists over how this transition occurs and whether it is driven largely by a reduction in the truncation radius of the disk8,9 or by a reduction in the spatial extent of the corona10,11. Observations of X-ray reverberation lags in supermassive black-hole systems12,13 suggest that the corona is compact and that the disk extends nearly to the central black hole14,15. Observations of stellar-mass black holes, however, reveal equivalent (mass-scaled) reverberation lags that are much larger16, leading to the suggestion that the accretion disk in the hard-X-ray state of stellar-mass black holes is truncated at a few hundreds of gravitational radii from the black hole17,18. Here we report X-ray observations of the black-hole transient MAXI J1820+07019,20. We find that the reverberation time lags between the continuum-emitting corona and the irradiated accretion disk are 6 to 20 times shorter than previously seen. The timescale of the reverberation lags shortens by an order of magnitude over a period of weeks, whereas the shape of the broadened iron K emission line remains remarkably constant. This suggests a reduction in the spatial extent of the corona, rather than a change in the inner edge of the accretion disk.
Title: Astronomy Thread
Post by: Star One on 01/09/2019 10:30 pm
Astronomers Uncover The Brightest Quasar In The Early Universe (http://keckobservatory.org/brightest_quasar)

https://youtu.be/ifOi4Uoa6JI
Title: Astronomy Thread
Post by: Star One on 01/10/2019 06:32 am
 'Screams' From a Black Hole's Edge Could Finally Let Us Measure Its Incredible Speed (https://www.sciencealert.com/brief-energy-blips-could-finally-unlock-the-secret-of-how-quickly-black-holes-spin)

Quote
Black holes are mysterious cosmic destroyers, but we just got one step closer to figuring out one of the key characteristics of how they work: how fast they're spinning.

Peering into the event horizon of a black hole, astronomers have detected brief X-ray pulses that indicate a rotation speed of a gob-smacking 50 percent of the speed of light.

What’s Better Than One Mysterious Cosmic Signal? (https://www.theatlantic.com/science/archive/2019/01/fast-radio-burst-repeating/579865/)

Quote
The two repeating signals have more in common than just their flashy nature. When FRBs arrive at Earth, many appear smeared across a range of frequencies, a sign of their long and bumpy journeys through cosmic material across the universe. This includes FRBs 121102 and 180814. But even though the bursts came from two very different locations, and carved out two very different paths to Earth, their radio waves showed similar distortion patterns.

This particular finding stunned astronomers at a recent conference, where the researchers teased their discovery with a little trick. “They put up images of these bursts, and everyone was like, ‘Okay, that looks familiar,’ and then the person showing it said, ‘Actually, you’ve never seen this before, because they’re from a new repeating FRB,’” said Shami Chatterjee, an astrophysicist at Cornell who studies FRBs and was not involved in the new research. “It looks shockingly similar.”

Title: Re: Astronomy Thread
Post by: SciNews on 01/10/2019 07:00 am
Press release: Canada’s CHIME telescope detects second repeating fast radio burst https://mcgill.ca/newsroom/channels/news/canadas-chime-telescope-detects-second-repeating-fast-radio-burst-292994
Research papers:
“Observations of fast radio bursts at frequencies down to 400 megahertz,” CHIME FRB Collaboration, Nature, published online Jan. 9, 2019. http://dx.doi.org/10.1038/s41586-018-0867-7
“The source of a second repeating fast radio burst,” CHIME FRB Collaboration, Nature, published online Jan. 9, 2019. http://dx.doi.org/10.1038/s41586-018-0864-x
Title: Re: Astronomy Thread
Post by: Star One on 01/10/2019 08:49 pm
Technosearch is a web-based tool that keeps track of SETI papers from 1960 until the present day and allows observers from all over the world to submit their own searches, keeping us current with the times.  Technosearch keeps track of the following: the title of the search paper (or the popular name of the search), the name of the observers, the date of the search, the objects observed, the facility at which the search took place, the size of the telescope used, the sensitivity of the instrument used, the resolving power of the instrument, the time that was spent observing each object, the reference where the search can be found in print, the link where the search can be found online, and comments that explain the search strategy and a place where the observer can make note of whatever else they would like to report.

https://technosearch.seti.org
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 01/15/2019 06:09 am
A circumbinary protoplanetary disk in a polar configuration (https://www.nature.com/articles/s41550-018-0667-x.epdf?author_access_token=bZKvvdOCZA-yoQOarTn4gNRgN0jAjWel9jnR3ZoTv0PcQUY0gj0KVPBjCZ3VxHV73kasQSCTnhMFzKLbVBNVTnRfvtNOUB9izTD8AaoKamvPvSk0YE5OmYdk_AjuavjrZ5YzANGmv-gSHQQiQHOgNg%3D%3D) (Nature astronomy, unapproved version)

Quote
(First paragraph)
Nearly all young stars are initially surrounded by ‘protoplanetary’ disks of gas and dust, and in the case of single stars at least 30% of these disks go on to form planets. The process of protoplanetary disk formation can result in initial misalignments, where the disk orbital plane is different from the stellar equator in single-star systems, or different from the binary orbital plane in systems with two stars. A quirk of the dynamics means that initially misaligned ‘circumbinary’ disks—those that surround two stars—are predicted to evolve to one of two possible stable configurations: one where the disk and binary orbital planes are coplanar and one where they are perpendicular (a ‘polar’ configuration). Previous work has found coplanar circumbinary disks, but no polar examples were known until now. Here, we report the first discovery of a protoplanetary circumbinary disk in the polar configuration, supporting the predictions that such disks should exist. The disk shows some characteristics that are similar to disks around single stars, and that are attributed to dust growth. Thus, the first stages of planet formation appear able to pro-ceed in polar circumbinary disks.

This Quadruple Star System Is Unlike Anything We’ve Ever Seen Before (https://gizmodo.com/this-quadruple-star-system-is-unlike-anything-we-ve-eve-1831747320?utm_medium=sharefromsite&utm_source=gizmodo_twitter&utm_campaign=top) (Gizmodo article on above paper)
Title: Re: Astronomy Thread
Post by: Star One on 01/16/2019 05:16 pm
10 Strange Aspects of Planet Venus

https://youtu.be/YtLFeye4-18
Title: Re: Astronomy Thread
Post by: SciNews on 01/16/2019 06:52 pm
10 Strange Aspects of Planet Venus
Recent research
Giant pattern discovered in the clouds of planet Venus http://www.kobe-u.ac.jp/research_at_kobe_en/NEWS/news/2019_01_09_01.html
Planetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer https://dx.doi.org/10.1038/s41467-018-07919-y
Title: Re: Astronomy Thread
Post by: Star One on 01/16/2019 07:22 pm
10 Strange Aspects of Planet Venus
Recent research
Giant pattern discovered in the clouds of planet Venus http://www.kobe-u.ac.jp/research_at_kobe_en/NEWS/news/2019_01_09_01.html
Planetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer https://dx.doi.org/10.1038/s41467-018-07919-y

Already posted here.

https://forum.nasaspaceflight.com/index.php?topic=18950.msg1900315#msg1900315
Title: Re: Astronomy Thread
Post by: Star One on 01/16/2019 08:01 pm
Bizarre Superfluid Could Explain the Existence of the Modern Universe (https://www.livescience.com/64511-helium-mimics-early-universe.html)

Quote
Scientists still aren't sure. But researchers have figured out a new way to model in a lab the sort of defect that could have caused the great unbalancing of the early universe. In a new paper, published today (Jan. 16) in the journal Nature Communications, scientists showed that they can use supercooled helium to model those first moments of existence — specifically, to re-create one possible set of conditions that may have existed just after the Big Bang.



Title: Re: Astronomy Thread
Post by: Star One on 01/17/2019 08:51 pm
Asteroid strikes 'increase threefold over last 300m years' (https://www.theguardian.com/science/2019/jan/17/asteroid-strikes-earth-moon-threefold-dinosaurs)

Quote
The rate at which asteroids are slamming into Earth has nearly tripled since the dinosaurs first roamed, according to a survey of the scars left behind.

Researchers worked out the rate of asteroid strikes on the moon and the Earth and found that in the past 290m years the number of collisions had increased dramatically.

Before that time, the planet suffered an asteroid strike about once every 3m years, but since then the rate has risen to once nearly every 1m years. The figures are based on collisions that left craters at least 10km (6.2 miles) wide.

Quote
The question now is whether the rate of asteroid strikes is still rising, or perhaps falling back to a lower level. Either way, Ghent believes there is no cause for alarm. “Because large impacts are very rare in the first place, even if you double or triple the probability they are still very rare,” she said.

Here’s the paper.

http://science.sciencemag.org/content/363/6424/253
Title: Astronomy Thread
Post by: Star One on 01/17/2019 08:56 pm
Scientists to Inaugurate Prototype Schwarzchild-Couder Telescope at Whipple Observatory in Preparation for First Light (https://www.cfa.harvard.edu/news/2019-02)

Amado, AZ &amp; Cambridge, MA -
Expected to see first light in early 2019, a prototype Schwarzschild-Couder Telescope (pSCT) for gamma-ray astronomy will be unveiled in a special inauguration event on January 17, 2019 at the Center for Astrophysics | Harvard &amp; Smithsonian, Fred Lawrence Whipple Observatory (FLWO) in Amado, Arizona.

Exploiting a novel optical design, the 9.7-m aperture pSCT is a pathfinder telescope for use in the next-generation very-high-energy gamma-ray observatory, the Cherenkov Telescope Array (CTA), for which construction will begin in 2019.

"The inauguration of the pSCT is an exciting moment for the institutions involved in its development and construction," said CTA-US Consortium Chair David Williams, a professor of physics at the University of California, Santa Cruz. "The first of its kind in the history of gamma-ray telescopes, the SCT design is expected to boost CTA performance towards the theoretical limit of the technology."

The SCT's complex dual-mirror optical system improves on the single-mirror designs traditionally used in gamma-ray telescopes by dramatically enhancing the optical quality of their focused light over a large region of the sky, and by enabling the use of compact, highly-efficient photo-sensors in the telescope camera.

"Ultimately, the SCT is designed to improve CTA's ability to detect very-high-energy gamma-ray sources, which may also be sources of neutrinos and gravitational waves," said Prof. Vladimir Vassiliev, Principal Investigator, pSCT. “Once the SCT technology is demonstrated at FLWO, it is hoped that SCTs will become a part of at least one of the two CTA arrays, located in each of the northern and southern hemispheres."

The CTA Observatory (CTAO) will consist of 118 telescopes of three different sizes, and is expected to detect sources of gamma rays in the energy range 20 GeV to 300 TeV with about ten times increased sensitivity compared to any current observatory. Notable for providing improved gamma-ray angular resolution and its very-high-resolution camera (&gt;11,000 pixels), the SCT is proposed for the medium-sized CTA telescopes, and will primarily contribute to the middle (80 GeV – 50 TeV) of CTA's energy range.

"The SCT and other telescopes at CTA will greatly improve upon current gamma-ray research being conducted at HAWC, HESS, MAGIC, and VERITAS, the last of which is located at the Fred Lawrence Whipple Observatory," said Dr. Wystan Benbow, Director, VERITAS. "Gamma-ray observatories like VERITAS have been operating for 12 to 16 years, and their many successes have brought very-high-energy gamma-ray astronomy into the mainstream, and have made many exciting discoveries. We hope CTA will supersede VERITAS around 2023, and it will be used to continue to build upon the 50 years of gamma-ray research at the Whipple Observatory and elsewhere."

About pSCT

The SCT optical design was first conceptualized by U.S. members of CTA in 2006, and the construction of the pSCT was funded in 2012. Preparation of the pSCT site at the base of Mt. Hopkins in Amado, AZ, began in late 2014, and the steel structure was assembled on site in 2016. The installation of pSCT’s 9.7-m primary mirror surface —consisting of 48 aspheric mirror panels—occurred in early 2018, and was followed by the camera installation in June 2018 and the 5.4-m secondary mirror surface installation—consisting of 24 aspheric mirror panels—in August 2018. Leading up to the inauguration and in preparation for first light, scientists opened the telescope’s optical surfaces in January 2019. The SCT is based on a 114 year-old dual-mirror optical system first proposed by Karl Schwarzschild in 1905, but only recently became possible to construct due to the critical research and development progress made at both the Brera Astronomical Observatory and Media Lario Technologies Incorporated in Italy. The pSCT was made possible by funding through the U.S. National Science Foundation Major Research Instrumentation program and by the contributions of thirty institutions and five critical industrial partners across the United States, Italy, Germany, Japan, and Mexico.

For more information visit https://www.cta-observatory.org/project/technology/sct/
Title: Re: Astronomy Thread
Post by: Star One on 01/18/2019 08:08 pm
From emergence to eruption: Comprehensive model captures life of a solar flare (https://www.sciencedaily.com/releases/2019/01/190116122654.htm)

Quote
A team of scientists has, for the first time, used a single, cohesive computer model to simulate the entire life cycle of a solar flare: from the buildup of energy thousands of kilometers below the solar surface, to the emergence of tangled magnetic field lines, to the explosive release of energy in a brilliant flash.
Title: Re: Astronomy Thread
Post by: Star One on 01/18/2019 08:30 pm
Making Stars When the Universe was Half Its Age
Friday, January 18, 2019
Science Update - A look at CfA discoveries from recent journals
The universe is about 13.8 billion years old, and its stars are arguably its most momentous handiwork. Astronomers studying the intricacies of star formation across cosmic time are trying to understand whether stars and the processes that produce them were the same when the universe was younger, about half its current age. They already know that from three to six billion years after the big bang stars were being made at a rate roughly ten times faster than they are today. How this happened, and why, are some of the key questions being posed for the next decade of research.

Star formation in a galaxy is thought to be triggered by the accretion of gas from the intergalactic medium (gas accretion via mergers between galaxies is thought to play a relatively minor role in the total numbers of stars produced). In galaxies that are actively making stars there is a tight relationship between their mass in stars and their rate of forming new stars, and this relationship approximately holds not only locally but even back when the universe was billions of years younger. In contrast, galaxies that are undergoing an active starburst - or the opposite, the quenching of star formation - fall above and below that relation respectively. The relationship supports the general picture of galaxy growth by gas accretion, except that for some reason smaller galaxies – those with fewer than about ten billion stars – seem to make slighter fewer stars than expected for their masses (the Milky Way is right at the turnover, with about ten billion stars and a rate of roughly one new star per year). A particularly significant consequence of this paucity, if real, is that simulations of galaxy growth do not show it, implying that the simulations are incorrect for smaller galaxies and that some physics is missing.

CfA astronomer Sandro Tacchella is a member of a team that used the Multi Unit Spectroscopic Explorer instrument on the VLT (Very Large Telescope) to obtain optical spectra of galaxies in the famous Hubble Deep Field South image of galaxies. They measured stellar emission lines in 179 distant galaxies in the field and used them to calculate the star formation behaviors after corrections for effects like dust extinction (which can make some of the optical lines appear weaker than they are). The find that the puzzle of depleted star formation in small galaxies is real at a level of roughly 5% even when accounting for noise and scatter in the data caused, for example, by galaxy evolution effects. The authors suggest that some kind of previously unaccounted for feedback may be responsible.

Reference(s):
"The MUSE Hubble Ultra Deep Field Survey XI. Constraining the low-mass end of the stellar mass – star formation rate relation at z &lt; 1," Leindert A. Boogaard, Jarle Brinchmann, Nicolas Bouché, Mieke Paalvast, Roland Bacon, Rychard J. Bouwens, Thierry, Madusha L. P. Gunawardhana, Hanae Inami, Rafaella A., Michael V. Maseda, Peter Mitchell, Themiya Nanayakkara, Johan Richard, Joop Schaye, Corentin Schreiber, Sandro Tacchella, Lutz Wisotzki, and Johannes Zabl, Astronomy &amp; Astrophysics 619, A27 2018.
Title: Re: Astronomy Thread
Post by: Blackstar on 01/18/2019 09:04 pm
https://www.nature.com/articles/d41586-019-00172-3?error=cookies_not_supported&code=0fbfd04c-3804-4bea-8f53-cd3c4a907749

NEWS 16 January 2019
US astronomers plot wish list for the next decade
Survey to set field’s priorities is haunted by ghosts of past efforts.


Title: Re: Astronomy Thread
Post by: SciNews on 01/22/2019 11:47 am
Impact on the Moon during the Jan.21 lunar eclipse
https://www.youtube.com/watch?v=FNvfBCu-jjI
https://twitter.com/jmmadiedo/status/1087639073899073536
Title: Re: Astronomy Thread
Post by: Star One on 01/22/2019 08:53 pm
Lifting the Veil on the Black Hole at the Heart of Our Galaxy (https://www.cfa.harvard.edu/news/2019-04)
Release No.:
2019-04
For Release:
Tuesday, January 22, 2019 - 12:00pm

Cambridge, MA -
A black hole four million times as massive as our Sun lurks at the center of the Milky Way. This black hole, called Sagittarius A* (Sgr A*), swallows nearby material that glows brightly as it approaches the event horizon. This galactic furnace is key to understanding black holes, but our view of it is obscured by lumpy clouds of electrons throughout the Galaxy. These clouds stretch, blur, and crinkle the image of Sgr A*, making it appear as though the black hole is blocked by an enormous sheet of frosted glass.

Now, a team of astronomers, led by Radboud University PhD student Sara Issaoun, have finally been able to see through these clouds and to study what makes the black hole glow. Issaoun completed this work while participating in the Predoctoral Program at the Smithsonian Astrophysical Observatory in Cambridge, MA.

"The source of the radiation from Sgr A* has been debated for decades," says Michael Johnson of the Center for Astrophysics | Harvard and Smithsonian (CfA). "Some models predict that the radiation comes from the disk of material being swallowed by the black hole, while others attribute it to a jet of material shooting away from the black hole. Without a sharper view of the black hole, we can’t exclude either possibility."

The team used the technique of Very Long Baseline Interferometry (VLBI), which combines many telescopes to form a virtual telescope the size of the Earth. The decisive advance was equipping the powerful ALMA array of telescopes in northern Chile with a new phasing system. This allowed it to join the GMVA, a global network of twelve other telescopes in North America and Europe.

"ALMA itself is a collection of more than 50 radio dishes. The magic of the new ALMA Phasing System is to allow all these dishes to function as a single telescope, which has the sensitivity of a single dish more than 75 meters across. That sensitivity, and its location high in the Andes mountains, makes it perfect for this Sgr A* study," says Shep Doeleman of the CfA, who was Principal Investigator of the ALMA Phasing Project.

"The breakthrough in image quality came from two factors," explains Lindy Blackburn, a radio astronomer at the CfA. "By observing at high frequencies, the image corruption from interstellar material was less significant, and by adding ALMA, we doubled the resolving power of our instrument."

The new images show that the radiation from Sgr A* has a symmetrical morphology and is smaller than expected – it spans a mere 300 millionth of a degree. "This may indicate that the radio emission is produced in a disk of infalling gas rather than by a radio jet," explains Issaoun, who tested computer simulations against the images. "However, that would make Sgr A* an exception compared to other radio-emitting black holes. The alternative could be that the radio jet is pointing almost directly at us."

Issaoun's supervisor Heino Falcke, Professor of Radio Astronomy at Radboud University, was surprised by this result. Last year, Falcke would have considered this new jet model implausible, but recently another set of researchers came to a similar conclusion using ESO's Very Large Telescope Interferometer of optical telescopes and an independent technique. "Maybe this is true after all," concludes Falcke, "and we are looking at this beast from a very special vantage point."

To learn more will require pushing these telescopes to even higher frequencies. "The first observations of Sgr A* at 86 GHz date from 26 years ago, with only a handful of telescopes. Over the years, the quality of the data has improved steadily as more telescopes join," says J. Anton Zensus, director of the Max Planck Institute for Radio Astronomy.

Michael Johnson is optimistic. "If ALMA has the same success in joining the Event Horizon Telescope at even higher frequencies, then these new results show that interstellar scattering will not stop us from peering all the way down to the event horizon of the black hole."

The results were published in The Astrophysical Journal.

This research was supported by grants from the European Research Council, the National Science Foundation, the Gordon and Betty Moore Foundation, and the John Templeton Foundation. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. This research made use of data obtained with the Global Millimeter VLBI Array (GMVA), consisting of telescopes operated by the Max-Planck-Institut für Radioastronomie (MPIfR), IRAM, Onsala, Metsahovi, Yebes, the Korean VLBI Network, the Green Bank Observatory and the Long Baseline Observatory (LBO). The GMVA is partially supported by the European Union's Horizon 2020 research and innovation program under grant agreement No 730562 (RadioNet). The VLBA is an instrument of the LBO, which is a facility of the National Science Foundation operated by Associated Universities, Inc. This work is partly based on observations with the 100-m telescope of the MPIfR at Effelsberg.

Headquartered in Cambridge, Mass., the Center for Astrophysics | Harvard &amp; Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
Title: Astronomy Thread
Post by: Star One on 01/22/2019 08:58 pm
 eso1902 — Photo Release
A Fleeting Moment in Time
European Southern Observatory’s Cosmic Gems Programme captures last breath of a dying star (https://www.eso.org/public/news/eso1902/)

How hot are atoms in the shock wave of an exploding star? (http://science.psu.edu/news-and-events/2019-news/Burrows1-2019)

Quote
New study of nearby supernova SN1987A answers longstanding debate
Title: Re: Astronomy Thread
Post by: Star One on 01/23/2019 08:22 pm
Physicists stimulate Hawking radiation from optical analogue of a black hole (https://physicsworld.com/a/physicists-stimulate-hawking-radiation-from-optical-analogue-of-a-black-hole/)

Quote
Stephen Hawking liked to claim that, if his most famous prediction had been verified experimentally, he would have won a Nobel prize. The prediction was that, as he once put it, “black holes ain’t so black”. These stars, which collapse to an infinitely dense singularity, can emit intense radiation from just outside their event horizon – the point of no return beyond which even light can’t escape from the intense gravity.
Title: Re: Astronomy Thread
Post by: Star One on 01/24/2019 08:36 pm
Scientists Explain Formation of Lunar Dust Clouds (https://iq.hse.ru/en/news/235207306.html)

Quote
Physicists from the Higher School of Economics and Space Research Institute have identified a mechanism explaining the appearance of two dusty plasma clouds resulting from a meteoroid that impacted the surface of the Moon. The study was published in JETP Letters.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 01/25/2019 03:01 am
Claim that two exoplanets are in the same orbit (trojans):

Co-orbital exoplanets from close period candidates: The TOI-178 case (https://arxiv.org/abs/1901.07250) (arXiv)

Quote
(Abstract)
Despite the existence of co-orbital bodies in the solar system, and the prediction of the formation of co-orbital planets by planetary system formation models, no co-orbital exoplanets (also called trojans) have been detected thus far. Here we study the signature of co-orbital exoplanets in transit surveys when two planet candidates in the system orbit the star with similar periods. Such pair of candidates could be discarded as false positives because they are not Hill-stable. However, horseshoe or long libration period tadpole co-orbital configurations can explain such period similarity. This degeneracy can be solved by considering the Transit Timing Variations (TTVs) of each planet. We then focus on the three planet candidates system TOI-178: the two outer candidates of that system have similar orbital period and had an angular separation near π/3 during the TESS observation of sector 2. Based on the announced orbits, the long-term stability of the system requires the two close-period planets to be co-orbitals. Our independent detrending and transit search recover and slightly favour the three orbits close to a 3:2:2 resonant chain found by the TESS pipeline, although we cannot exclude an alias that would put the system close to a 4:3:2 configuration. We then analyse in more detail the co-orbital scenario. We show that despite the influence of an inner planet just outside the 2:3 mean-motion resonance, this potential co-orbital system can be stable on the Giga-year time-scale for a variety of planetary masses, either on a trojan or a horseshoe orbit. We predict that large TTVs should arise in such configuration with a period of several hundred days. We then show how the mass of each planet can be retrieved from these TTVs.

The claimed co-orbital planets both appear to have radii greater than that of Earth. This has implications for the planet/dwarf planet distinction, so I've cross-posted this to the 'Pluto-Planet debate discussions' thread for those interested.
Title: Re: Astronomy Thread
Post by: jgoldader on 01/25/2019 02:50 pm
This is an interesting article about an analysis of a small rock returned by Apollo 14, that suggests the rock might actually have formed on Earth.  The idea is that the rock formed on Earth, then was blasted into space by one of the large impacts that were common during planetary formation, and ended up on the Moon.  I remember reading a journal article some years ago looking at the possibility that there are pieces of the early Earth and Mars on the lunar surface. 

https://phys.org/news/2019-01-moon-recovered-astronauts-earth.html?utm_source=menu&utm_medium=link&utm_campaign=item-menu

Because of tectonics and erosion, there's basically none of the Earth's primordial crust actually left on Earth, but perhaps we can find pieces on the Moon.
Title: Re: Astronomy Thread
Post by: Star One on 01/28/2019 07:27 am
The First-Ever Photo of a Black Hole Is Almost Ready. Here's What It Might Look Like (https://www.sciencealert.com/black-hole-event-horizon-accretion-disc-jean-pierre-luminet-event-horizon-telescope)

Quote
But long before the EHT, there was an astrophysicist named Jean-Pierre Luminet. All the way back in 1978, he already gave us what could be thought of as the very first image of a black hole's event horizon.

It's not, of course, an actual photo. Luminet, whose background was in mathematics, used his skillset to perform the first computer simulation of what a black hole might look like to an observer, using a 1960s punch card IBM 7040 computer.
Title: Astronomy Thread
Post by: Star One on 01/28/2019 05:57 pm
It seems the universe is expanding even faster than thought before as measured by quasars rather than supernovae.

Cosmological constraints from the Hubble diagram of quasars at high redshifts]https://www.nature.com/articles/s41550-018-0657-z]Cosmological constraints from the Hubble diagram of quasars at high redshifts (https://www.nature.com/articles/s41550-018-0657-z)

The concordance model (Λ cold dark matter (ΛCDM) model, where Λ is the cosmological constant) reproduces the main current cosmological observations1,2,3,4 assuming the validity of general relativity at all scales and epochs and the presence of CDM and of Λ, equivalent to dark energy with a constant density in space and time. However, the ΛCDM model is poorly tested in the redshift interval between the farthest observed type Ia supernovae5 and the cosmic microwave background. We present measurements of the expansion rate of the Universe based on a Hubble diagram of quasars. Quasars are the most luminous persistent sources in the Universe, observed up to redshifts of z ≈ 7.5 (refs. 6,7). We estimate their distances following a method developed by our group8,9,10, based on the X-ray and ultraviolet emission of the quasars. The distance modulus/redshift relation of quasars at z &lt; 1.4 is in agreement with that of supernovae and with the concordance model. However, a deviation from the ΛCDM model emerges at higher redshift, with a statistical significance of ~4σ. If an evolution of the dark energy equation of state is allowed, the data suggest dark energy density increasing with time.
Title: Re: Astronomy Thread
Post by: eeergo on 01/29/2019 12:56 am
How will the foreseeable gap between JWST/WFIRST and the next-generation space telescopes be spanned in the US? NSF funding for ground-based astronomy to the rescue: Giant Magellan Telescope (GMT) and Thirty-Meter Telescope (TMT).

https://spacenews.com/the-future-of-space-based-astronomy-may-depend-on-two-large-ground-based-telescopes/
Title: Re: Astronomy Thread
Post by: eeergo on 01/29/2019 06:09 am
A bit technical, but I found this critical look at what is in fact a 30-year-old field extremely interesting for those of us who weren't around (scientifically, at least) at the time:

A personal recollection of how we learned to stop worrying and love the Lambda

Quote
[...] we should remember that we once endowed SCDM with the same absolute certainty we now attribute to ΛCDM. I was there, 3,000 internet years ago, when SCDM failed. There is nothing so sacred in ΛCDM that it can’t suffer the same fate, as has every single cosmology ever devised by humanity.

https://tritonstation.wordpress.com/2019/01/28/a-personal-recollection-of-how-we-learned-to-stop-worrying-and-love-the-lambda/
Title: Astronomy Thread
Post by: Star One on 01/29/2019 08:09 pm
Shows you how much amateur equipment has advanced in recent times.

Astronomers Discover Rare Kilometer-Sized Object in Outer Solar System (https://motherboard.vice.com/en_us/article/59xbg8/astronomers-discover-rare-kilometer-sized-object-in-outer-solar-system)

Quote
Scientists have discovered a tiny object in the Kuiper belt beyond Neptune, a kilometer-scale world that could shed light on how planets formed in the early days of the solar system.

The find—which marks the first time that a world smaller than ten kilometers has been detected in this part of the solar system—seems like it would require high-resolution telescopes like the 10-meter Keck Observatory in Hawaii. However, it was actually spotted by two modest “amateur telescopes,” according to research published Monday in Nature Astronomy.
Title: Re: Astronomy Thread
Post by: whitelancer64 on 01/29/2019 08:45 pm
Shows you how much amateur equipment has advanced in recent times.

Astronomers Discover Rare Kilometer-Sized Object in Outer Solar System (https://motherboard.vice.com/en_us/article/59xbg8/astronomers-discover-rare-kilometer-sized-object-in-outer-solar-system)

Quote
Scientists have discovered a tiny object in the Kuiper belt beyond Neptune, a kilometer-scale world that could shed light on how planets formed in the early days of the solar system.

The find—which marks the first time that a world smaller than ten kilometers has been detected in this part of the solar system—seems like it would require high-resolution telescopes like the 10-meter Keck Observatory in Hawaii. However, it was actually spotted by two modest “amateur telescopes,” according to research published Monday in Nature Astronomy.

"The astronomers used 11-inch Celestron telescopes, which are worth about $3,000 each, as well as specialized cameras and astrographs. They placed the telescopes on a school roof on Miyako Island, Japan, located off the east coast of Taiwan."

I think it's worth noting that Miyako island is pretty small, just about 10 miles across, and it's in between Okinawa and Taiwan, roughly 100 miles away from either, near the south edge of the East China Sea. There must be some nice dark skies at that location.
Title: Re: Astronomy Thread
Post by: Star One on 01/29/2019 09:37 pm
Citizen Scientists Find New World with NASA Telescope (https://exoplanets.nasa.gov/news/1543/citizen-scientists-find-new-world-with-nasa-telescope/)

Quote
Using data from NASA's Kepler space telescope, citizen scientists have discovered a planet roughly twice the size of Earth located within its star's habitable zone, the range of orbital distances where liquid water may exist on the planet's surface. The new world, known as K2-288Bb, could be rocky or could be a gas-rich planet similar to Neptune. Its size is rare among exoplanets - planets beyond our solar system.
Title: Re: Astronomy Thread
Post by: Star One on 01/30/2019 03:11 pm
 Astronomers spot mysterious long 'trash bag' object floating above Earth (https://www.independent.co.uk/news/science/earth-satellite-trash-bag-object-mysterious-ufo-astronomers-a8754201.html)

Quote
A mysterious "empty trash bag" object has been spotted floating above Earth.

The satellite is thought to be several metres across but is extremely lightweight, the astronomers who spotted it say.

The object is probably a piece of light material, such as metallic foil, that has been left over from a rocket launch. But it is not clear what rocket launch the object known as A10bMLz could have been launched from.

Quote
Such "empty trash bag" objects have been spotted before. But this is the first one that has ever been seen drifting at such a distant orbit.

The object was first seen by Hawaii's Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope. Further analysis by the NBO confirmed that the object was very light but relatively wide, as well as its strange orbit.
Title: Astronomy Thread
Post by: Star One on 01/31/2019 08:52 pm
 HUBBLE FORTUITOUSLY DISCOVERS A NEW GALAXY IN THE COSMIC NEIGHBOURHOOD [HEIC1903] (http://sci.esa.int/hubble/61075-hubble-fortuitously-discovers-a-new-galaxy-in-the-cosmic-neighbourhood-heic1903/)

Quote
Astronomers using the NASA/ESA Hubble Space Telescope to study some of the oldest and faintest stars in the globular cluster NGC 6752 have made an unexpected finding. They discovered a dwarf galaxy in our cosmic backyard, only 30 million light-years away. The finding is reported in the journal Monthly Notices of the Royal Astronomical Society: Letters

Ancient asteroid impacts played a role in creation of Earth's future continents (https://www.eurekalert.org/pub_releases/2019-01/uotw-aai013119.php)

Quote
The heavy bombardment of terrestrial planets by asteroids from space has contributed to the formation of the early evolved crust on Earth that later gave rise to continents
Title: Astronomy Thread
Post by: Star One on 02/04/2019 07:41 pm
Goodbye to a beauty in the night sky (https://nouvelles.umontreal.ca/en/article/2019/01/29/goodbye-to-a-beauty-in-the-night-sky/)

Quote
The overshadowing of the Homunculus nebula of Eta Carinae isn't entirely a bad thing. Astronomers will soon be better able to see the star itself.

Colliding Exoplanets (https://www.cfa.harvard.edu/news/2019-05)

Quote
There are currently about 2000 confirmed exoplanets with radii less than about three Earth-radii, and measurements of their densities reveal an astonishing diversity. Some have densities lower than Neptune which is made mostly of volatiles (materials less dense than metal and rock, but Neptune has almost four times the Earth's radius), while others appear to have rock-like densities, as high as the Earth's or higher. Such a wide range of compositions may be the product of the different initial conditions in the planet-formation process, or it could be because something dramatic happens to the planet to alter its initial properties as it evolves.


Title: Re: Astronomy Thread
Post by: Star One on 02/05/2019 05:57 am
Magnetic north just changed. Here's what that means. (https://www.nationalgeographic.com/science/2019/02/magnetic-north-update-navigation-maps/)

Quote
Magnetic north has never sat still. In the last hundred years or so, the direction in which our compasses steadfastly point has lumbered ever northward, driven by Earth's churning liquid outer core some 1,800 miles beneath the surface. Yet in recent years, scientists noticed something unusual: Magnetic north's routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why.
Title: Astronomy Thread
Post by: Star One on 02/05/2019 08:14 pm
Breakthrough Listen generates huge amounts of data, particularly from the two main radio telescopes where we're doing routine observations, Green Bank and Parkes (and we'll be generating even more once we begin routine observations with MeerKAT. Part of our mission is to make as much of that data as possible publicly accessible, and to that end we have a substantial amount of data already in the Breakthrough Listen Open Data Archive, with much more to come in the near future. We've also made available some tutorials to accompany the data, including one that enables you to see the signal from the Voyager spacecraft in data taken with the Green Bank Telescope in amazing detail, given that it's 20 billion kilometers from Earth.

seti.berkeley.edu:8000/open-data/ (http://seti.berkeley.edu:8000/open-data/)
Title: Re: Astronomy Thread
Post by: Cinder on 02/05/2019 09:24 pm
Magnetic north just changed. Here's what that means. (https://www.nationalgeographic.com/science/2019/02/magnetic-north-update-navigation-maps/)

Quote
Magnetic north has never sat still. In the last hundred years or so, the direction in which our compasses steadfastly point has lumbered ever northward, driven by Earth's churning liquid outer core some 1,800 miles beneath the surface. Yet in recent years, scientists noticed something unusual: Magnetic north's routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why.
Also said was that the South Pole is basically unmoving and that there's no serious expectation that this is precursor to polarity switch.
Title: Re: Astronomy Thread
Post by: Star One on 02/06/2019 06:30 am
The Simple Case For Why Physics Needs A Particle Collider Beyond The LHC (https://medium.com/starts-with-a-bang/the-simple-case-for-why-physics-needs-a-particle-collider-beyond-the-lhc-62cab9621f77)

Quote
On the other hand, the Standard Model doesn’t explain everything that we know must exist. Dark matter, dark energy, the values of the fundamental constants, and the origin of why our Universe is made of matter and not antimatter are all outstanding, unsolved puzzles. When the Large Hadron Collider (LHC) turned on in 2008, it was designed to find the Standard Model’s last holdout: the Higgs boson. But no other mystery has yet been solved. Some contend this means another collider won’t be worth it. In reality, it means we need one now more than ever.
Title: Re: Astronomy Thread
Post by: eeergo on 02/07/2019 08:33 am
The Simple Case For Why Physics Needs A Particle Collider Beyond The LHC (https://medium.com/starts-with-a-bang/the-simple-case-for-why-physics-needs-a-particle-collider-beyond-the-lhc-62cab9621f77)

Quote
On the other hand, the Standard Model doesn’t explain everything that we know must exist. Dark matter, dark energy, the values of the fundamental constants, and the origin of why our Universe is made of matter and not antimatter are all outstanding, unsolved puzzles. When the Large Hadron Collider (LHC) turned on in 2008, it was designed to find the Standard Model’s last holdout: the Higgs boson. But no other mystery has yet been solved. Some contend this means another collider won’t be worth it. In reality, it means we need one now more than ever.

Quite a biased article (towards the dominant high energy collider physicist's view) IMHO.

What the author waves off as "exotic" paths in a couple of lines, saying that "finesse approach" will be "pursued regardless", is actually where the real, low-hanging mysteries lie right now, and many paths aren't just exotic curiosities. Neutrino oscillations are firmly and well-established, although still holding many secrets, and they are the only true departure from the SM ever observed. Just as higher-energy collider physics was the discipline where clearly something new was to be found (the SM's predictions at the GeV scale), now most reasonable supersymmetric zoos have been killed off, there isn't a firm motivation to keep on trudging along that path, when others offer much greater potential.

Sure, surprises can always happen, but money (and people) aren't infinite. It is questionable to strive for that cherrypicker when the appletree 10 meters out has ripe apples at ground level - especially when the ILC and the Chinese LHC are kind of in the lead to get that crane.

This links well with the space industry view of "make it and they will come": sometimes it is dicey to step away from some favored approach, even if perceived as not the optimal spending route, because maybe those funds won't be better spent and will just evaporate (see STS). But I don't think this is such a case.
Title: Re: Astronomy Thread
Post by: eeergo on 02/07/2019 12:47 pm
https://twitter.com/TioVitolan/status/1093351189826162688

Puebla's Large Millimeter Telescope (LMT) has shut down non-essential operations because of insecurity in the area.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 02/07/2019 07:21 pm
Magnetic north just changed. Here's what that means. (https://www.nationalgeographic.com/science/2019/02/magnetic-north-update-navigation-maps/)

Quote
Magnetic north has never sat still. In the last hundred years or so, the direction in which our compasses steadfastly point has lumbered ever northward, driven by Earth's churning liquid outer core some 1,800 miles beneath the surface. Yet in recent years, scientists noticed something unusual: Magnetic north's routine plod has shifted into high gear, sending it galloping across the Northern Hemisphere—and no one can entirely explain why.

Also said was that the South Pole is basically unmoving and that there's no serious expectation that this is precursor to polarity switch.

To be pedantic, magnetic north is the Earth's south pole (which is why the north pole of a magnet points towards it). What is unmoving is magnetic south, which is the Earth's north pole, and which is situated near Vostok base in Antarctica (hence the pub quiz question 'why can it be correct to say that Santa's workshop is in Antarctica?'). :)
Title: Astronomy Thread
Post by: Star One on 02/12/2019 07:56 pm
Liberal Sprinkling of Salt Discovered around a Young Star (https://public.nrao.edu/news/2019-alma-salt-star/)

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ALMA discovered ordinary table salt in a not-so-ordinary location: 1,500 light-years from Earth in the disk surrounding a massive young star.

Zwicky Transient Facility Spots a Bumper Crop of Supernovae, Black Holes and more (https://cmns.umd.edu/news-events/features/4333)

Quote
UMD astronomers contribute to a wealth of discoveries described in seven new publications

The Zwicky Transient Facility (ZTF), an automated sky survey project based at Caltech's Palomar Observatory near San Diego, California, has produced its first bounty of new results. Since officially beginning operations in March 2018, the new instrument has discovered 50 small near-Earth asteroids and more than 1,100 supernovae, while observing more than 1 billion stars in the Milky Way galaxy.
Title: Re: Astronomy Thread
Post by: Star One on 02/13/2019 08:18 pm
There’s Evidence that Mars is Still Volcanically Active (https://www.universetoday.com/141481/theres-evidence-that-mars-is-still-volcanically-active/#more-141481)

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A new study shows that Mars may very well be volcanically active. Nobody’s seen direct evidence of volcanism; no eruptions or magma or anything like that. Rather, the proof is in the water.

In the past, Mars was a much warmer and wetter place. Now, Mars is still home to lots of water, mostly as vapor and ice. But in August 2018, a study published in Science showed a 20-km-wide lake of liquid water underneath solid ice at the Martian South Pole. The authors of that study suggested that the water was probably kept in liquid state by the pressure from above, and by dissolved salt content.

But this new research shows that pressure and salt couldn’t have prevented that water from freezing. Only volcanic activity could have kept it warm enough. Specifically, a magma chamber formed in the last few hundred years is the only way that that water could’ve been prevented from freezing.
Title: Re: Astronomy Thread
Post by: Star One on 02/17/2019 08:11 pm
Not surprised that the study came to this conclusion.

Study blames YouTube for rise in number of Flat Earthers (https://www.theguardian.com/science/2019/feb/17/study-blames-youtube-for-rise-in-number-of-flat-earthers)

Quote
Of the 30, all but one said they had not considered the Earth to be flat two years ago but changed their minds after watching videos promoting conspiracy theories on YouTube. “The only person who didn’t say this was there with his daughter and his son-in-law and they had seen it on YouTube and told him about it,” said Asheley Landrum, who led the research at Texas Tech University.

The interviews revealed that most had been watching videos about other conspiracies, with alternative takes on 9/11, the Sandy Hook school shooting and whether Nasa really went to the moon, when YouTube offered up Flat Earth videos for them to watch next.

Some said they watched the videos only in order to debunk them but soon found themselves won over by the material.

Title: Astronomy Thread
Post by: Star One on 02/18/2019 08:36 pm
 First Evidence Discovered of a Gigantic Remnant Around an Exploding Star (http://newscenter.sdsu.edu/sdsu_newscenter/news_story.aspx?sid=77527)

Quote
A San Diego State University astrophysicist has helped discover evidence of a gigantic remnant surrounding an exploding star—a shell of material so huge, it must have been erupting on a regular basis for millions of years.

A 5km asteroid may briefly occult the brightest star in the night sky
Unfortunately, the path for this event will occur mostly (https://arstechnica.com/science/2019/02/a-small-asteroid-may-briefly-blot-out-sirius-monday-night/)

Quote
Sirius, a binary system, is the brightest star in the night sky. The larger of the two stars, Sirius A, is about 25 times more luminous than the Sun, and Sirius is relatively nearby, at less than 9 light years from our Solar System.

On Monday night, for a few areas of South and Central America, as well as the Caribbean, Sirius will probably briefly disappear. This will occur as a small asteroid passes in front of the star, occulting it for up to 1.6 seconds, according to the International Occultation Timing Association. (Yes, the acronym is IOTA).

In this case, the asteroid 4388 Jürgenstock will have an apparent diameter just an iota bigger than Sirius. The angular diameter of the asteroid is about 0.007 arcseconds (an arcsecond is 1/3,600th of a degree of the night sky), whereas the angular diameter of Sirius is 0.006 arcseconds. Thus, as the asteroid passes in front of Sirius, the star will briefly dim, perhaps completely, before quickly brightening again. Sirius may appear to blink once, slowly.
Title: Astronomy Thread
Post by: Star One on 02/19/2019 06:36 am
Unfortunately most of this is behind a paywall but this is the only article I can find for this so far.

 Signal of first known exomoon may actually be from Jupiter-like planet (https://www.newscientist.com/article/2194289-signal-of-first-known-exomoon-may-actually-be-from-jupiter-like-planet/)
Title: Astronomy Thread
Post by: Star One on 02/19/2019 07:35 pm
Seismologists Discover Mountain Ranges 410 Miles Below Earth’s Surface (https://www.popularmechanics.com/science/environment/a26409144/underground-mountain-ranges/)

Quote
Understanding more about the remnants of such ancient tectonic plates and how they have impacted the chemical composition of the mantle will help seismologists understand how Earth formed, how it changes over time, and how these changes impact our planet’s integrity and longevity. It’s like the real-world geophysicists’ redux on Jules Verne’s Journey to the Center of the Earth, 155 years later. Just enough time for science-fiction to become science.

Citizen Scientist Finds Ancient White Dwarf Star Encircled by Puzzling Rings (https://www.nasa.gov/feature/goddard/2019/citizen-scientist-finds-ancient-white-dwarf-star-encircled-by-puzzling-rings)

Quote
A volunteer working with the NASA-led Backyard Worlds: Planet 9 project has found the oldest and coldest known white dwarf — an Earth-sized remnant of a Sun-like star that has died — ringed by dust and debris. Astronomers suspect this could be the first known white dwarf with multiple dust rings.

The star, LSPM J0207+3331 or J0207 for short, is forcing researchers to reconsider models of planetary systems and could help us learn about the distant future of our solar system.

“This white dwarf is so old that whatever process is feeding material into its rings must operate on billion-year timescales,” said John Debes, an astronomer at the Space Telescope Science Institute in Baltimore. “Most of the models scientists have created to explain rings around white dwarfs only work well up to around 100 million years, so this star is really challenging our assumptions of how planetary systems evolve.”

A paper detailing the findings, led by Debes, was published in the Feb. 19 issue of The Astrophysical Journal Letters and is now available online.
Title: Re: Astronomy Thread
Post by: Star One on 02/20/2019 10:03 pm
Tiny Neptune Moon May Have Broken from Larger Moon (https://solarsystem.nasa.gov/news/854/tiny-neptune-moon-may-have-broken-from-larger-moon/)

Quote
Astronomers call it "the moon that shouldn't be there."

After several years of analysis, a team of planetary scientists using NASA's Hubble Space Telescope has at last come up with an explanation for a mysterious moon around Neptune that they discovered with Hubble in 2013.

The tiny moon, named Hippocamp, is unusually close to a much larger Neptunian moon called Proteus. Normally, a moon like Proteus should have gravitationally swept aside or swallowed the smaller moon while clearing out its orbital path.

So why does the tiny moon exist? Hippocamp is likely a chipped-off piece of the larger moon that resulted from a collision with a comet billions of years ago. The diminutive moon, only 20 miles (about 34 kilometers) across, is 1/1000th the mass of Proteus (which is 260 miles [about 418 kilometers] across).
Title: Re: Astronomy Thread
Post by: Star One on 02/22/2019 07:55 pm
Where are all the aliens? Struggling and hustling, just like us (https://www.popsci.com/where-are-aliens-new-model?src=SOC&amp;dom=tw)

Quote
We must be the only fledgling fliers in the cosmic neighborhood, as various astrophysicists have suggested for decades. But a new analysis from a team led by University of Rochester astrophysicist Adam Frank suggests a more nuanced resolution to the old paradox. Sweeping across the Milky Way and establishing a unified galactic empire might be inevitable for a monolithic super-civilization, but most cultures are neither monolithic nor super—at least if our experience is any guide. Spaceships break down. Overactive stars roast otherwise desirable targets. Economic crises and government shutdowns kill nascent starships before they get off the ground.
Title: Astronomy Thread
Post by: Star One on 03/04/2019 07:58 pm
Intermediate mass black hole found near galactic centre (https://astronomynow.com/2019/02/28/intermediate-mass-black-hole-found-near-galactic-centre/)

Quote
Intrigued by a swirling cloud of gas near the heart of the Milky Way, a team of astronomers led by Shunya Takekawa at the National Astronomical Observatory of Japan used the Atacama Large Millimetre/submillimetre Array to measure its motion and concluded the only explanation was a previously unknown intermediate-mass black hole.

 M33 Data Collection Complete!]M33 Data Collection Complete! (https://clustersearch.wordpress.com/2019/02/28/m33-data-collection-complete/)

Quote
It has only been two months since we first launched the Local Group Cluster Search, but I’m pleased to announce that we’ve completed our first galaxy target: the Triangulum galaxy, M33!  All 4,428 Hubble Space Telescope search images have been retired after each was classified by 60 people.  More than 1500 volunteers have pitched in on the effort — we can’t thank you enough for all your hard work!
Title: Astronomy Thread
Post by: Star One on 03/05/2019 08:43 pm
The case of the over-tilting exoplanets (https://news.yale.edu/2019/03/04/case-over-tilting-exoplanets)

Quote
For almost a decade, astronomers have tried to explain why so many pairs of planets outside our solar system have an odd configuration — their orbits seem to have been pushed apart by a powerful unknown mechanism. Yale researchers say they’ve found a possible answer, and it implies that the planets’ poles are majorly tilted.

The finding could have a big impact on how researchers estimate the structure, climate, and habitability of exoplanets as they try to identify planets that are similar to Earth. The research appears in the March 4 online edition of the journal Nature Astronomy.

Astronomers are Using NASA’s Deep Space Network to Hunt for Magnetars (https://www.universetoday.com/141652/astronomers-are-using-nasas-deep-space-network-to-hunt-for-magnetars/)

Quote
Right, magnetars. Perhaps one of the most ferocious beasts to inhabit the cosmos. Loud, unruly, and temperamental, they blast their host galaxies with wave after wave of electromagnetic radiation, running the gamut from soft radio waves to hard X-rays. They are rare and poorly understood.

Some of these magnetars spit out a lot of radio waves, and frequently. The perfect way to observe them would be to have a network of high-quality radio dishes across the world, all continuously observing to capture every bleep and bloop. Some sort of network of deep-space dishes.

Title: Re: Astronomy Thread
Post by: Star One on 03/07/2019 04:46 pm
 What if It's Not Dark Matter Making The Universe's Extra 'Gravity', But Light? (https://www.sciencealert.com/what-if-it-s-not-dark-matter-making-the-universe-s-extra-gravity-but-light)

Quote
In a new paper, they lay out an argument that light particles (photons) are at least partially the source of the phenomenon - causing an effect that isn't gravity, but behaves a heck of a lot like it.

"The hypothetical effect we are investigating is not the result of increased gravity," Budker said.

"By assuming a certain photon mass, much smaller than the current upper limit, we can show that this mass would be sufficient to generate additional forces in a galaxy and that these forces would be roughly large enough to explain the rotation curves. This conclusion is extremely exciting."
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/07/2019 07:43 pm
What if It's Not Dark Matter Making The Universe's Extra 'Gravity', But Light? (https://www.sciencealert.com/what-if-it-s-not-dark-matter-making-the-universe-s-extra-gravity-but-light)

Quote
In a new paper, they lay out an argument that light particles (photons) are at least partially the source of the phenomenon - causing an effect that isn't gravity, but behaves a heck of a lot like it.

"The hypothetical effect we are investigating is not the result of increased gravity," Budker said.

"By assuming a certain photon mass, much smaller than the current upper limit, we can show that this mass would be sufficient to generate additional forces in a galaxy and that these forces would be roughly large enough to explain the rotation curves. This conclusion is extremely exciting."

But does this proposed mechanism also explain the other observations to which dark matter is put forward as an explanation - galaxy clusters, gravitational lensing, cosmic microwave background etc? If not, this proposal, far from providing an alternative to dark energy, may instead serve to provide a much tighter upper bound on the photon mass!
Title: Re: Astronomy Thread
Post by: Star One on 03/07/2019 08:11 pm
What if It's Not Dark Matter Making The Universe's Extra 'Gravity', But Light? (https://www.sciencealert.com/what-if-it-s-not-dark-matter-making-the-universe-s-extra-gravity-but-light)

Quote
In a new paper, they lay out an argument that light particles (photons) are at least partially the source of the phenomenon - causing an effect that isn't gravity, but behaves a heck of a lot like it.

"The hypothetical effect we are investigating is not the result of increased gravity," Budker said.

"By assuming a certain photon mass, much smaller than the current upper limit, we can show that this mass would be sufficient to generate additional forces in a galaxy and that these forces would be roughly large enough to explain the rotation curves. This conclusion is extremely exciting."

But does this proposed mechanism also explain the other observations to which dark matter is put forward as an explanation - galaxy clusters, gravitational lensing, cosmic microwave background etc? If not, this proposal, far from providing an alternative to dark energy, may instead serve to provide a much tighter upper bound on the photon mass!

It was my interpretation that they were claiming that this part of the explanation not all of it. Also that their theory needed further work.
Title: Astronomy Thread
Post by: Star One on 03/11/2019 07:58 pm
A Sparse Population of Small Kuiper Belt Objects? (https://www.centauri-dreams.org/2019/03/11/a-sparse-population-of-small-kuiper-belt-objects/)

Quote
Thus a measure of how much in the dark we are about the nature of KBOs. Even Pluto, with resurfacing at work through geological processes, should show more signs of small craters of 13 kilometers or less in diameter. Their lack seems to make small KBOs — 1 to 2 kilometers in diameter — very sparse. The work, which appears in Science, implies that there are major differences between the Kuiper Belt and the closest analogue in our system, the main asteroid belt. Says Singer:

Radioactive particles from huge solar storm found in Greenland (https://www.theguardian.com/science/2019/mar/11/radioactive-particles-from-huge-solar-storm-found-in-greenland)

Quote
Traces of an enormous solar storm that battered the atmosphere and showered Earth in radioactive particles more than 2,500 years ago have been discovered under the Greenland ice sheet.

Scientists studying ice nearly half a kilometre beneath the surface found a band of radioactive elements unleashed by a storm that struck the planet in 660BC.

It was at least 10 times more powerful than any recorded by instruments set up to detect such events in the past 70 years, and as strong as the most intense known solar storm, which hit Earth in AD775.

Our Galaxy Could Have 50 Billion Rogue Planets (https://www.popularmechanics.com/space/deep-space/a26788244/milky-way-rogue-planets/)

Quote
Our galaxy has planets aplenty. Our Sun possesses at least eight of them, and in recent years we’ve learned that most other stars have some, too.

But according to a new simulation of star behavior, a staggering number of planets aren’t orbiting any star at all. Instead, there could be 50 billion rogue planets are adrift in the Milky Way.

Title: Re: Astronomy Thread
Post by: Star One on 03/13/2019 07:13 am
 UK Put a Black Hole on a 50p Coin to Honour Stephen Hawking, And It Looks Stunning (https://www.sciencealert.com/the-royal-mint-has-put-a-black-hole-onto-a-50p-coin-to-honour-stephen-hawking)

Quote
If you've ever been concerned that British currency doesn't feature enough astrophysical equations, we have good news. Although the collector's item, sold on the Royal Mint website, won't be released into circulation, the stunning coin displays the formula describing a black hole's entropy.

Rather than featuring a portrait of the scientist himself, the designer went for something far more abstract, and yet something Stephen Hawking, who had a great sense of humour, would hopefully have approved of.
Title: Re: Astronomy Thread
Post by: Star One on 03/15/2019 07:56 pm
This is way too technical for me to express an opinion.

Venus is not Earth’s closest neighbor (https://physicstoday.scitation.org/do/10.1063/PT.6.3.20190312a/full/)

Quote
Calculations and simulations confirm that on average, Mercury is the nearest planet to Earth—and to every other planet in the solar system.
Title: Re: Astronomy Thread
Post by: Nomadd on 03/15/2019 09:15 pm
This is way too technical for me to express an opinion.

Venus is not Earth’s closest neighbor (https://physicstoday.scitation.org/do/10.1063/PT.6.3.20190312a/full/)

Quote
Calculations and simulations confirm that on average, Mercury is the nearest planet to Earth—and to every other planet in the solar system.
It's just a bunch of nonsense by people acting like they've come up with something by playing word games.
Title: Re: Astronomy Thread
Post by: Star One on 03/15/2019 10:52 pm
This is way too technical for me to express an opinion.

Venus is not Earth’s closest neighbor (https://physicstoday.scitation.org/do/10.1063/PT.6.3.20190312a/full/)

Quote
Calculations and simulations confirm that on average, Mercury is the nearest planet to Earth—and to every other planet in the solar system.
It's just a bunch of nonsense by people acting like they've come up with something by playing word games.

As Spock would say even what I could follow seemed illogical.
Title: Astronomy Thread
Post by: Star One on 03/16/2019 10:11 am
Will post a non-paywalled link for this story once I find a decent one. As at the moment this appears to be the only article on this.

 Huge meteor explosion over Earth last year went unnoticed until now (https://www.newscientist.com/article/2196702-huge-meteor-explosion-over-earth-last-year-went-unnoticed-until-now/)

Quote
A meteor caused a massive explosion over Earth last year, but nobody noticed until now. It is the second-largest recorded impact in the past century, after the meteor that exploded over the Russian region of Chelyabinsk in 2013.

The giant fireball hit at 2350 GMT on 18 December over the Bering Sea, a part of the Pacific Ocean between Russia and Alaska.

Cooking up Alien Atmospheres on Earth (https://www.jpl.nasa.gov/news/news.php?feature=7350)

Quote
Researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, are cooking up an alien atmosphere right here on Earth. In a new study, JPL scientists used a high-temperature "oven" to heat a mixture of hydrogen and carbon monoxide to more than 2,000 degrees Fahrenheit (1,100 Celsius), about the temperature of molten lava. The aim was to simulate conditions that might be found in the atmospheres of a special class of exoplanets (planets outside our solar system) called "hot Jupiters."
Title: Re: Astronomy Thread
Post by: faramund on 03/16/2019 08:53 pm
This is way too technical for me to express an opinion.

Venus is not Earth’s closest neighbor (https://physicstoday.scitation.org/do/10.1063/PT.6.3.20190312a/full/)

Quote
Calculations and simulations confirm that on average, Mercury is the nearest planet to Earth—and to every other planet in the solar system.
It's just a bunch of nonsense by people acting like they've come up with something by playing word games.

As Spock would say even what I could follow seemed illogical.

I don't think this can really just be dismissed as out of hand. Its very similar to.. Is the Sun closer to us, on average, than Venus. On average the Sun is 1AU away. The distance to Venus is much smaller to that when its close, but when its on the far side. Its over 1AU away. To believe that averages either less than, equal to, or over 1AU. I can't really say.

The paper that's linked to ran simulations of the orbits of the planets, and recorded the average distances every 24 hours - and that's where they derived their results. In the lack of any counter argument, I tend to think their findings are reasonable.

Of course, the average distance doesn't really matter that much. The closest distance is what is often biased towards, i.e. better resolution of ground- (or orbit)- based telescopes, preferred trajectories, etc.
Title: Re: Astronomy Thread
Post by: eeergo on 03/16/2019 10:38 pm
I don't think this can really just be dismissed as out of hand. Its very similar to.. Is the Sun closer to us, on average, than Venus. On average the Sun is 1AU away. The distance to Venus is much smaller to that when its close, but when its on the far side. Its over 1AU away. To believe that averages either less than, equal to, or over 1AU. I can't really say.

The paper that's linked to ran simulations of the orbits of the planets, and recorded the average distances every 24 hours - and that's where they derived their results. In the lack of any counter argument, I tend to think their findings are reasonable.

Of course, the average distance doesn't really matter that much. The closest distance is what is often biased towards, i.e. better resolution of ground- (or orbit)- based telescopes, preferred trajectories, etc.

It's a matter of definition and akin to asking if the Sun is rotating around the Earth or viceversa. You can perfectly describe it as the former, but it will give you insanely complicated solutions while the latter is a much more reasonable way to formalize it - while also giving you more insight.

You don't need simulations to record that distance, it can be done analytically, since the orbits and the equation of distance between two points are too - they just found it easier to do it that way, although it's an needlessly rough approximation, with only 365 points. And of course, this "average distance throughout the year" was probably already calculated much earlier, perhaps even in the XVIII century.

Furthermore, the argument they make is void since it just takes into account *linear* Euclidean distance. Apart from philosophical arguments, this bit of trivia (I refuse to call it "finding", at least the result they got) is not applicable to anything: doesn't describe trajectories, or observation opportunities, or even occultations.

We could also calculate which NEA is closest on average to, say, Tasmania - but is it worth your time, or to write an article about it?
Title: Re: Astronomy Thread
Post by: faramund on 03/17/2019 02:56 am
I don't think this can really just be dismissed as out of hand. Its very similar to.. Is the Sun closer to us, on average, than Venus. On average the Sun is 1AU away. The distance to Venus is much smaller to that when its close, but when its on the far side. Its over 1AU away. To believe that averages either less than, equal to, or over 1AU. I can't really say.

The paper that's linked to ran simulations of the orbits of the planets, and recorded the average distances every 24 hours - and that's where they derived their results. In the lack of any counter argument, I tend to think their findings are reasonable.

Of course, the average distance doesn't really matter that much. The closest distance is what is often biased towards, i.e. better resolution of ground- (or orbit)- based telescopes, preferred trajectories, etc.

It's a matter of definition and akin to asking if the Sun is rotating around the Earth or viceversa. You can perfectly describe it as the former, but it will give you insanely complicated solutions while the latter is a much more reasonable way to formalize it - while also giving you more insight.

You don't need simulations to record that distance, it can be done analytically, since the orbits and the equation of distance between two points are too - they just found it easier to do it that way, although it's an needlessly rough approximation, with only 365 points. And of course, this "average distance throughout the year" was probably already calculated much earlier, perhaps even in the XVIII century.

Furthermore, the argument they make is void since it just takes into account *linear* Euclidean distance. Apart from philosophical arguments, this bit of trivia (I refuse to call it "finding", at least the result they got) is not applicable to anything: doesn't describe trajectories, or observation opportunities, or even occultations.

We could also calculate which NEA is closest on average to, say, Tasmania - but is it worth your time, or to write an article about it?
1) They do the simulations for 10 000 years
2) They also solve the system analytically - the simulation results are there, I assume, as a cross-check/validation of their analytical result.
3) I agree this has low real-world applicability.
Title: Re: Astronomy Thread
Post by: eeergo on 03/17/2019 03:45 am

1) They do the simulations for 10 000 years
2) They also solve the system analytically - the simulation results are there, I assume, as a cross-check/validation of their analytical result.
3) I agree this has low real-world applicability.


Admittedly, I had just skimmed through the article, so mea culpa on not catching the details (although I would like you to make me unsee their "whirly-dirly corollary" expression).


Their analytical solution is however, needlessly, an approximation. An exact analytical formula can be "trivially" (meaning it will be complicated) determined by finding the vector that joins whichever planets together, by subtracting each planet's orbital trajectory with respect to the Sun at a given time.


As for the 10k years... it doesn't really matter for the cases under discussion, as a much smaller number of years would do (that is, the planet's zodiac (https://www.eso.org/public/outreach/eduoff/vt-2004/Education/edu1app5.html), who would ever think astrology would be more useful than "scientific studies"!), and actually seems another blind brute-force approach to a problem that is actually well-defined. I guess it's easier to just have a computer do the thinking for you these days.


Their rediscovery of the proverbial "dodecahedral wheel" and their wild unsupported claim that "nobody ever came up with anything like this" is what makes this sophism so unsightly. More so when it always gives the same result, even for Pluto (!!) The icing on the cake is their accusation other educational sites do it all wrong because they consider the difference between circular orbits and not their useless time average, while going as far as plotting "error" percentage comparisons...
Title: Re: Astronomy Thread
Post by: faramund on 03/17/2019 06:01 am

1) They do the simulations for 10 000 years
2) They also solve the system analytically - the simulation results are there, I assume, as a cross-check/validation of their analytical result.
3) I agree this has low real-world applicability.


Admittedly, I had just skimmed through the article, so mea culpa on not catching the details (although I would like you to make me unsee their "whirly-dirly corollary" expression).


Their analytical solution is however, needlessly, an approximation. An exact analytical formula can be "trivially" (meaning it will be complicated) determined by finding the vector that joins whichever planets together, by subtracting each planet's orbital trajectory with respect to the Sun at a given time.


As for the 10k years... it doesn't really matter for the cases under discussion, as a much smaller number of years would do (that is, the planet's zodiac (https://www.eso.org/public/outreach/eduoff/vt-2004/Education/edu1app5.html), who would ever think astrology would be more useful than "scientific studies"!), and actually seems another blind brute-force approach to a problem that is actually well-defined. I guess it's easier to just have a computer do the thinking for you these days.


Their rediscovery of the proverbial "dodecahedral wheel" and their wild unsupported claim that "nobody ever came up with anything like this" is what makes this sophism so unsightly. More so when it always gives the same result, even for Pluto (!!) The icing on the cake is their accusation other educational sites do it all wrong because they consider the difference between circular orbits and not their useless time average, while going as far as plotting "error" percentage comparisons...

I don't have strong objections to anything here. I can't judge your 2nd paragraph comments, although the joy of science is you could always implement that approach, and compare with this and publish it.

The third paragraph is a bit harsh, they did develop a theoretical model - which is the brain work, and then did the simulation to verify it. Which leads to the 4th paragraph, the "error" comparisons show their honesty - it looks like their theory isn't complete (which is fine - lots of theories aren't), and the errors show how much more could be done (maybe with your 2nd para approach).
Title: Re: Astronomy Thread
Post by: eeergo on 03/17/2019 07:09 am
I don't have strong objections to anything here. I can't judge your 2nd paragraph comments, although the joy of science is you could always implement that approach, and compare with this and publish it.

The third paragraph is a bit harsh, they did develop a theoretical model - which is the brain work, and then did the simulation to verify it. Which leads to the 4th paragraph, the "error" comparisons show their honesty - it looks like their theory isn't complete (which is fine - lots of theories aren't), and the errors show how much more could be done (maybe with your 2nd para approach).

That's the thing, you see: I don't need to because it's already done :) Possibly even published (as a student exercise, because this approach brings little insight). And it will be more precise, by definition, because it's an analytical solution which doesn't discretize continuous phenomena.

I don't need to develop a model calculating the coordinates of the North Pole relative to asteroid Itokawa during a million years to know that model doesn't describe anything generally useful. By this metric, anyone could publish their grad school (or undergrad!) projects and say "to our knowledge nobody has done this quite as us".

The "theoretical model" they developed is middle school geometry, they then applied it to a trivial problem (long studied for centuries) and went on to blindly fire up some pre-existing code, not showing much insight into *how* to run it, to verify their approach is approximate, while claiming foul on others when they are talking about a different concept that is clear to anyone over 5 years old. Your equidistance baffles me, I'm not sure if you're just playing devil's advocate - you seem to be saying an "incomplete" theory such as, say, geocentrism, is fine because other theories are too, like you know, the Standard Model lacks a formulation for gravity.
Title: Re: Astronomy Thread
Post by: faramund on 03/17/2019 09:00 am


That's the thing, you see: I don't need to because it's already done :) Possibly even published (as a student exercise, because this approach brings little insight). And it will be more precise, by definition, because it's an analytical solution which doesn't discretize continuous phenomena.

I don't need to develop a model calculating the coordinates of the North Pole relative to asteroid Itokawa during a million years to know that model doesn't describe anything generally useful. By this metric, anyone could publish their grad school (or undergrad!) projects and say "to our knowledge nobody has done this quite as us".

The "theoretical model" they developed is middle school geometry, they then applied it to a trivial problem (long studied for centuries) and went on to blindly fire up some pre-existing code, not showing much insight into *how* to run it, to verify their approach is approximate, while claiming foul on others when they are talking about a different concept that is clear to anyone over 5 years old. Your equidistance baffles me, I'm not sure if you're just playing devil's advocate - you seem to be saying an "incomplete" theory such as, say, geocentrism, is fine because other theories are too, like you know, the Standard Model lacks a formulation for gravity.

In my mind, this is just how science goes. Someone brings out a theory or approach that tries to explain something. Usually its not perfect, it'll have some good bits and some bad bits. Later on, someone else will try to refine the theory, or propose a better new one, and so it goes.

This is a bit why I might seem equidistant about your opinion of how simple/naive their approach is. It seems entirely possible that a better approach is possible, but that's not the point, whenever a scientific paper comes out, there's often (in my field (AI) almost always) an assumption that it can be done better.

As to how simple/naive it is. I can't judge that, but presumably Physics Today put it through a review process, and ended up accepting it for publication.

So this paper, just seems like a typical early PhD paper, in some ways a learning process. They've developed a theory (possibly an overly simple one), done some work to verify it (the simulations), and reported their errors. In some ways, this is a standard paper format. I do think they oversold the value of their work, but doing so is moderately common, and to some degree necessary when trying to get a paper published.
Title: Re: Astronomy Thread
Post by: RotoSequence on 03/17/2019 09:28 am
It would probably make a good gotcha-question for Quite Interesting, if nothing else.  :P
Title: Re: Astronomy Thread
Post by: eeergo on 03/18/2019 01:48 am
In my mind, this is just how science goes. Someone brings out a theory or approach that tries to explain something. Usually its not perfect, it'll have some good bits and some bad bits. Later on, someone else will try to refine the theory, or propose a better new one, and so it goes.

This is a bit why I might seem equidistant about your opinion of how simple/naive their approach is. It seems entirely possible that a better approach is possible, but that's not the point, whenever a scientific paper comes out, there's often (in my field (AI) almost always) an assumption that it can be done better.

As to how simple/naive it is. I can't judge that, but presumably Physics Today put it through a review process, and ended up accepting it for publication.

So this paper, just seems like a typical early PhD paper, in some ways a learning process. They've developed a theory (possibly an overly simple one), done some work to verify it (the simulations), and reported their errors. In some ways, this is a standard paper format. I do think they oversold the value of their work, but doing so is moderately common, and to some degree necessary when trying to get a paper published.

Yes, it's common, doesn't mean it's good practice - especially when the simplifications are so blatant and there're HUGE precedents on how it can be done not only better, but the best way possible.

Still, as I said before, what makes this article so unsightly is their willful, cheery ignorance of prior literature (which is a fundamental cornerstone in any serious publication, not just a nice add-on) and, most of all, their accusation of mispractice by others, who aren't studying the same concept, by using a completely tergiversated error chart.

Physics Today may or may not have peer-reviewed it - being such a short article perhaps they just checked it adhered to publication guidelines without really challenging the content. Even if indeed it was reviewed, lots can be said about the shortcomings of peer review these days, and this could be an example.

IMO we have grossly overdiscussed this inconsequential work long enough, so I'm gonna leave it at that :)
Title: Re: Astronomy Thread
Post by: eeergo on 03/18/2019 01:54 am
It would probably make a good gotcha-question for Quite Interesting, if nothing else.  :P

Same level of gotcha than telling a mailman who works on an neighborhood circuit that the person he routinely is closest to is the waitress of a McDonalds lying close to the center of that circuit, rather than his wife at home.
Title: Re: Astronomy Thread
Post by: RotoSequence on 03/18/2019 01:59 am
It would probably make a good gotcha-question for Quite Interesting, if nothing else.  :P

Same level of gotcha than telling a mailman who works on an neighborhood circuit that the person he routinely is closest to is the waitress of a McDonalds lying close to the center of that circuit, rather than his wife at home.

QI thrives on technically accurate trivia that holds no wider meaning.
Title: Re: Astronomy Thread
Post by: Star One on 03/18/2019 06:51 am
US detects huge meteor explosion (http://www.bbc.co.uk/news/amp/science-environment-47607696)

Quote
A huge fireball exploded in the Earth's atmosphere in December, according to Nasa.

The blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago.

But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula.

The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb.

Lindley Johnson, planetary defence officer at Nasa, told BBC News a fireball this big is only expected about two or three times every 100 years.

Title: Re: Astronomy Thread
Post by: bkellysky on 03/18/2019 04:26 pm
This is way too technical for me to express an opinion.

Venus is not Earth’s closest neighbor (https://physicstoday.scitation.org/do/10.1063/PT.6.3.20190312a/full/)

Quote
Calculations and simulations confirm that on average, Mercury is the nearest planet to Earth—and to every other planet in the solar system.

I was surprised to learn in Sky and Telescope a few years ago that Mercury was most often the closest planet to Earth.  There is so much fuss about Martian close approaches and I knew Venus comes the closest of all the planets to Earth.  Because Mercury does not get too far from Earth, it is most frequently the closest planet to Earth.

I plotted a graph of distance from Earth to Mercury, Venus and Mars for two years centered on this month, attached here and at my blog at https://bkellysky.wordpress.com/2019/03/18/which-planet-is-closest-to-earth-most-often/
Title: Re: Astronomy Thread
Post by: eeergo on 03/18/2019 11:46 pm
I was surprised to learn in Sky and Telescope a few years ago that Mercury was most often the closest planet to Earth.  There is so much fuss about Martian close approaches and I knew Venus comes the closest of all the planets to Earth.  Because Mercury does not get too far from Earth, it is most frequently the closest planet to Earth.

I plotted a graph of distance from Earth to Mercury, Venus and Mars for two years centered on this month, attached here and at my blog at https://bkellysky.wordpress.com/2019/03/18/which-planet-is-closest-to-earth-most-often/

But that's the thing, it's a trivial result that for any given planet, any circularly-orbiting object arbitrarily close to its star (with the limit being the star around which the planet under consideration orbits) will be closest to it on average.

You can even see it intuitively: as you plotted, the sinusoidals will start getting flatter and flatter until you reach a flat constant line (the system's star), while any other circularly-orbiting object farther from the star will be closer at some point of its orbit, but also diametrically-opposite the star at some other moment, increasing the average distance for at least half of its orbit. Unless you're considering something in the planet-star Lagrange points, this is the case for a suitably long time period (to account for close-coorbiting bodies) for any planet, star and distance considered, provided it's a circular orbit as the article considers.

The farther the considered planet orbits, the clearer this effect gets - hence why Mercury is the closest planet, on average, to *any* of the Solar System's planets, and even to Pluto whose results gets a bit more complicated due to eccentricity and plane inclination issues.
Title: Re: Astronomy Thread
Post by: ugordan on 03/19/2019 03:20 pm
US detects huge meteor explosion (http://www.bbc.co.uk/news/amp/science-environment-47607696)

Scott Manley has a Himawari image sequence in his new video: https://www.youtube.com/watch?v=fpaxvjFh-qA
Title: Astronomy Thread
Post by: Star One on 03/19/2019 07:06 pm
Talking longer term I think there is a possibility that the Earth will see an uptick in impacts over the next million years as I was reading an article in Astronomy Now January 2019 issue that there is a theory that Gaia data will show that Scholz’s Star went further into the Oort Cloud 70,000 years ago than initial calculations showed. That the information to prove or disprove this theory will be in the next Gaia data release.
Title: Re: Astronomy Thread
Post by: Rondaz on 03/20/2019 08:19 pm
Dancing the Lunar Transit

By Sarah Frazier NASA’s Goddard Space Flight Center
March 20, 2019

On March 6, 2019, our Solar Dynamics Observatory, or SDO, witnessed a lunar transit — where both the Sun and Moon displayed a little odd behavior.

First, there was the transit itself. A lunar transit occurs when the Moon passes between SDO and the Sun, blocking the satellite’s view. But instead of appearing on one side of the frame and disappearing on the other, the Moon seemed to pause and double back partway through crossing the Sun. No, the Moon didn’t suddenly change directions in space: This is an optical illusion, a trick of perspective.

Here’s how it happened: SDO is in orbit around Earth. When the transit started, the satellite was moving crosswise between the Sun and Earth, nearly perpendicular to the line between them, faster than the Moon. But during the transit, SDO started the dusk phase of its orbit — when it’s traveling around towards the night side of Earth, moving almost directly away from the Sun — but no longer making any progress horizontally to the Sun. The Moon, however, continued to move perpendicular to the Sun and thus could “overtake” SDO. From SDO’s perspective, the Moon appeared to move in the opposite direction.

The second, subtler part of this celestial dance seemed to come from the Sun itself. If you look closely, you may notice the Sun seems to wiggle a bit, side-to-side and up and down, during the transit. That’s another result of SDO’s perspective, though in a different way.

SDO relies on solar limb sensors to keep its view steady and focused on the Sun. These limb sensors consist of four light sensors arranged in a square. To keep the Sun exactly centered in its telescopes, SDO is trained to move as needed to keep all four sensors measuring the same amount of light.

But when the Moon covers part of the Sun, the amount of light measured by some of the sensors drops. This makes SDO think it’s not pointed directly at the Sun, which would cause SDO to repoint — unless that function gets overridden.

Since SDO’s fine guidance system wouldn’t be much use during a lunar transit regardless, the mission team commands the spacecraft to disregard limb sensor data at the beginning of such transits. This loss of fine guidance accounts for some of the Sun’s apparent movement: SDO is now pointing at a general Sun-ward spot in space, instead of keeping its view steady using the much more accurate limb sensors.

The other factor behind the apparently wiggly Sun is temperature. SDO’s instruments are designed to work in the full glare of the Sun’s light and heat. When the Moon’s shadow passes over the spacecraft, the instruments quickly cool in the vacuum of space and start to bend and flex. The flexing of the front part of the telescope can make it look like the image is moving around in the frame.

SDO’s operators use strategically-placed heaters onboard the spacecraft to minimize this flexing as much as possible and to get back to providing science-quality data — images that are focused, centered and steady — as quickly as possible.

https://blogs.nasa.gov/sunspot/2019/03/20/dancing-the-lunar-transit/
Title: Re: Astronomy Thread
Post by: Star One on 03/22/2019 06:44 am
Astronomers find 83 quasars already shining in early universe (https://astronomynow.com/2019/03/18/astronomers-find-83-quasars-already-shining-in-early-universe/)

Quote
Astronomers studying some of the most ancient light in the cosmos have found 83 ancient quasars in a field where only 17 were previously known, an indication that supermassive black holes must have been relatively common in the extremely early universe. The discovery, using the Hyper Suprime-Cam wide field camera mounted on the Subaru Telescope, required 300 nights of observation time over five years.
Title: Astronomy Thread
Post by: Star One on 03/22/2019 04:30 pm
Best-Yet Measurements Deepen Cosmological Crisis (https://www.scientificamerican.com/article/best-yet-measurements-deepen-cosmological-crisis/)

Quote
A long-running dispute about how fast our universe is expanding just became even more entrenched. New and more precise measurements of stars in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, have only strengthened the differences between two independent methods of calculating the expansion rate.
This impasse may soon force cosmologists to reexamine the “standard model” of cosmology, which tells us about the composition of the universe (radiation, normal matter, dark matter and dark energy) and how it has evolved over time.

Referring to the above article something is clearly wrong and it looks to be the standard model.

Quote
Scientists have announced the observation of “CP violation in a D0 meson” at CERN, a discovery that will appear in physics textbooks for years to come. You’re probably wondering what exactly it means.

The Universe is full of regular matter. There’s also antimatter, which exists even here on Earth, but there’s much less of it. This new observation is important on its own, but it also takes physicists another step closer to explaining where all the antimatter has disappeared to.

https://gizmodo.com/why-an-incredible-new-cern-observation-has-physicists-p-1833466787
Title: Re: Astronomy Thread
Post by: Star One on 03/22/2019 08:15 pm
NASA Instruments Image Fireball over Bering Sea (https://www.jpl.nasa.gov/news/news.php?feature=7355)

On Dec. 18, 2018, a large "fireball" - the term used for exceptionally bright meteors that are visible over a wide area - exploded about 16 miles (26 kilometers) above the Bering Sea. The explosion unleashed an estimated 173 kilotons of energy, or more than 10 times the energy of the atomic bomb blast over Hiroshima during World War II.

Two NASA instruments aboard the Terra satellite captured images of the remnants of the large meteor. The image sequence shows views from five of nine cameras on the Multi-angle Imaging SpectroRadiometer (MISR) instrument taken at 23:55 Coordinated Universal Time (UTC), a few minutes after the event. The shadow of the meteor's trail through Earth's atmosphere, cast on the cloud tops and elongated by the low sun angle, is to the northwest. The orange-tinted cloud that the fireball left behind by super-heating the air it passed through can be seen below and to the right of the GIF's center.

The still image, captured by the Moderate Resolution Imaging SpectroRadiometer (MODIS) instrument, is a true-color image showing the remnants of the meteor's passage, seen as a dark shadow cast on thick, white clouds. MODIS captured the image at 23:50 UTC.

The Dec. 18 fireball was the most powerful meteor to be observed since 2013; however, given its altitude and the remote area over which it occurred, the object posed no threat to anyone on the ground. Fireball events are actually fairly common and are recorded in the NASA Center for Near Earth Object Studies database.

The Terra spacecraft was launched in 1999 and is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. The MISR instrument was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for NASA's Science Mission Directorate in Washington. JPL is a division of Caltech. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, Virginia. The MODIS instrument is managed by NASA's Goddard Space Flight Center.

More information about MISR and MODIS is available at the following site(s):

https://www-misr.jpl.nasa.gov/

https://terra.nasa.gov/about/terra-instruments/modis

Title: Re: Astronomy Thread
Post by: edzieba on 03/25/2019 04:19 pm
I don't need to develop a model calculating the coordinates of the North Pole relative to asteroid Itokawa during a million years to know that model doesn't describe anything generally useful.
Replace 'North Pole' with 'Nagano Prefecture', you have a useful tool for signal strength between Usuda ground station and Hayabusa. Plenty of "that's dumb / it's so obvious / everyone knows that / why would anyone ever bother to calculate that?!" research turns out to be useful.
For Mercury being the average closest planetary body to all other planetary bodies (and most minor planets sharing the same plane) it may mean that designs for a system-side data relay network may have a reason to place a node in Mercury orbit (or somewhere nice and shielded like a shadow-skirting Lissajous around Mercury-Sun L2).
Title: Re: Astronomy Thread
Post by: eeergo on 03/25/2019 06:18 pm
I don't need to develop a model calculating the coordinates of the North Pole relative to asteroid Itokawa during a million years to know that model doesn't describe anything generally useful.
Replace 'North Pole' with 'Nagano Prefecture', you have a useful tool for signal strength between Usuda ground station and Hayabusa. Plenty of "that's dumb / it's so obvious / everyone knows that / why would anyone ever bother to calculate that?!" research turns out to be useful.

No, because the analytical "method" they used only works for circular orbits (Itokawa's e=0.3) and considers point-like objects.

My comment was a hyperbole, and furthermore you decontextualized it from the intended meaning, i.e. I don't need to create another unuseful model to understand theirs is.

There still are analytical exact formulas, not too complicated to derive even if cumbersome, to get that distance. Discovered hundreds of years ago. Using standard trigonometry. Could even add a phase for Earth's rotation and account for day/night cutouts.

Quote
For Mercury being the average closest planetary body to all other planetary bodies (and most minor planets sharing the same plane) it may mean that designs for a system-side data relay network may have a reason to place a node in Mercury orbit (or somewhere nice and shielded like a shadow-skirting Lissajous around Mercury-Sun L2).

Mercury would only make the slightest bit of sense if used as a shade as you mention - otherwise you can just use any orbit close to the Sun for minimizing average distance to other circularly-orbiting bodies.

Although I would argue you'd be more interested in minimizing the r^2 losses for smaller periods (or just using several relays) rather than having huge losses all the time which, funny fact, turn out to be smaller on a "yearly" average, when that "year" might last hundreds of Earth years. The Sun would still be in the middle for a significant portion of the orbit.
Title: Re: Astronomy Thread
Post by: Star One on 03/25/2019 08:35 pm
Jupiter's unknown journey through the early solar system revealed (https://m.phys.org/news/2019-03-jupiter-unknown-journey-early-solar.html)

Quote
The results show that Jupiter was formed four times further from the sun than its current position would indicate. "This is the first time we have proof that Jupiter was formed a long way from the sun and then migrated to its current orbit. We found evidence of the migration in the Trojan asteroids orbiting close to Jupiter," explains Simona Pirani, doctoral student in astronomy at Lund University, and the lead author of the study.

Quote
The authors of the study also suggest that the gas giant Saturn and the ice giants Uranus and Neptune could have migrated in a similar way.
Title: Astronomy Thread
Post by: Star One on 03/25/2019 08:51 pm
And this week’s way out physics theory is there is no reality only information. I looked up his new book and that sounds like some light bedtime reading...

Physics Is Pointing Inexorably to Mind (https://blogs.scientificamerican.com/observations/physics-is-pointing-inexorably-to-mind/)

Quote
In his 2014 book, Our Mathematical Universe, physicist Max Tegmark boldly claims that “protons, atoms, molecules, cells and stars” are all redundant “baggage.” Only the mathematical apparatus used to describe the behavior of matter is supposedly real, not matter itself. For Tegmark, the universe is a “set of abstract entities with relations between them,” which “can be described in a baggage-independent way”—i.e., without matter. He attributes existence solely to descriptions, while incongruously denying the very thing that is described in the first place. Matter is done away with and only information itself is taken to be ultimately real.
This abstract notion, called information realism is philosophical in character, but it has been associated with physics from its very inception. Most famously, information realism is a popular philosophical underpinning for digital physics. The motivation for this association is not hard to fathom.
Title: Re: Astronomy Thread
Post by: CuddlyRocket on 03/26/2019 05:19 pm
And this week’s way out physics theory is there is no reality only information.

It would be more accurate to describe the theory as saying that the only reality is information.
Title: Re: Astronomy Thread
Post by: Star One on 03/26/2019 09:19 pm
And this week’s way out physics theory is there is no reality only information.

It would be more accurate to describe the theory as saying that the only reality is information.

You are quite correct that’s a more accurate description than mine.
Title: Re: Astronomy Thread
Post by: Star One on 03/28/2019 07:33 pm
NASA's Hubble nabs spectacular image of asteroid coming apart (https://www.cnet.com/news/nasas-hubble-nabs-spectacular-image-of-asteroid-coming-apart/)

Quote
Because of constant pressure from the sun, a space rock beyond Mars is spinning so much that it's literally cracking up.
Title: Re: Astronomy Thread
Post by: Star One on 03/28/2019 08:02 pm
Persistence of intense, climate-driven runoff late in Mars history (http://advances.sciencemag.org/content/5/3/eaav7710)

Quote
Mars is dry today, but numerous precipitation-fed paleo-rivers are found across the planet’s surface. These rivers’ existence is a challenge to models of planetary climate evolution. We report results indicating that, for a given catchment area, rivers on Mars were wider than rivers on Earth today. We use the scale (width and wavelength) of Mars paleo-rivers as a proxy for past runoff production. Using multiple methods, we infer that intense runoff production of &gt;(3–20) kg/m2 per day persisted until &lt;3 billion years (Ga) ago and probably &lt;1 Ga ago, and was globally distributed. Therefore, the intense runoff production inferred from the results of the Mars Science Laboratory rover was not a short-lived or local anomaly. Rather, precipitation-fed runoff production was globally distributed, was intense, and persisted intermittently over &gt;1 Ga. Our improved history of Mars’ river runoff places new constraints on the unknown mechanism that caused wet climates on Mars.
Title: Re: Astronomy Thread
Post by: Star One on 03/29/2019 12:40 pm
Debunking this nonsense story.

Here's The Truth About That Photo of 'Mushrooms' Growing on Mars (https://www.sciencealert.com/here-s-the-truth-about-that-photo-of-mushrooms-growing-on-mars)

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A peculiar new paper, published in a little-known scientific journal, has the tabloids stirred up about the possibility of life on Mars.

According to this paper, an international team of scientists are now claiming to have found evidence of 'mushrooms' growing on the surface of the Red Planet.

The 'evidence' is primarily based on images, taken by NASA's Curiosity and Opportunity rovers, which capture a birds-eye-view of what look like, well, mushrooms.
Title: Astronomy Thread
Post by: Star One on 03/29/2019 08:31 pm
Astronomers discover mysterious star displaying never-seen-before behaviour (https://www.eso.org/public/usa/blog/what-is-this/)

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Many, if not most, stars vary in brightness, typically by just a little and very predictably. These changes occur on timescales from minutes to years, and can tell us about the internal structure of stars in a way that no other observations can. But recently, a team of astronomers used ESO facilities to discover an extreme variable star named VVV-WIT-07, with WIT being short for “What is this?”. Seen from Earth, this strange star suddenly and irregularly reduces in brightness by 30–40%. In one extraordinary case it even dimmed by about 80%. But “normal” stars just don’t do that. The research was led by Roberto Saito from the Universidade Federal de Santa Catarina. ESO astronomer Valentin Ivanov was involved in the research and tells us more.

Interesting title on the paper.

https://arxiv.org/pdf/1811.02265.pdf
Title: Astronomy Thread
Post by: Star One on 03/30/2019 09:59 am
GRAVITY instrument breaks new ground in exoplanet imaging (https://www.eso.org/public/usa/news/eso1905/)

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The GRAVITY instrument on ESO’s Very Large Telescope Interferometer (VLTI) has made the first direct observation of an exoplanet using optical interferometry. This method revealed a complex exoplanetary atmosphere with clouds of iron and silicates swirling in a planet-wide storm. The technique presents unique possibilities for characterising many of the exoplanets known today.

New evidence of deep groundwater on Mars (https://www.eurekalert.org/pub_releases/2019-03/uosc-neo032719.php)

Quote
In mid-2018, researchers supported by the Italian Space Agency detected the presence of a deep-water lake on Mars under its south polar ice caps. Now, researchers at the USC Arid Climate and Water Research Center (AWARE) have published a study that suggests deep groundwater could still be active on Mars and could originate surface streams in some near-equatorial areas on Mars.

The researchers at USC have determined that groundwater likely exists in a broader geographical area than just the poles of Mars and that there is an active system, as deep as 750 meters, from which groundwater comes to the surface through cracks in the specific craters they analyzed.
Title: Re: Astronomy Thread
Post by: Star One on 04/04/2019 08:17 pm
 Newfound tiny planet may be a glimpse of Earth's ultimate fate (https://www.nationalgeographic.com/science/2019/04/planet-found-orbiting-white-dwarf-may-be-a-glimpse-of-earths-fate/)

Quote
A ball of rock discovered orbiting a white dwarf star hints at what our solar system might look like in about five billion years.
Title: Re: Astronomy Thread
Post by: Star One on 04/09/2019 05:58 am
 Jupiter's Atmosphere Heats up under Solar Wind (https://www.jpl.nasa.gov/news/news.php?release=2019-059&amp;rn=news.xml&amp;rst=7369)

New Earth-based telescope observations show that auroras at Jupiter's poles are heating the planet's atmosphere to a greater depth than previously thought - and that it is a rapid response to the solar wind.

"The solar wind impact at Jupiter is an extreme example of space weather," said James Sinclair of NASA's Jet Propulsion Laboratory in Pasadena, California, who led new research published April 8 in Nature Astronomy. "We're seeing the solar wind having an effect deeper than is normally seen."

Auroras at Earth's poles (known as the aurora borealis at the North Pole and aurora australis at the South Pole) occur when the energetic particles blown out from the Sun (the solar wind) interact with and heat up the gases in the upper atmosphere. The same thing happens at Jupiter, but the new observations show the heating goes two or three times deeper down into its atmosphere than on Earth, into the lower level of Jupiter's upper atmosphere, or stratosphere.

Understanding how the Sun's constant outpouring of solar wind interacts with planetary environments is key to better understanding the very nature of how planets and their atmospheres evolve.

"What is startling about the results is that we were able to associate for the first time the variations in solar wind and the response in the stratosphere - and that the response to these variations is so quick for such a large area," said JPL's Glenn Orton, co-author and part of the observing team.

Within a day of the solar wind hitting Jupiter, the chemistry in its atmosphere changed and its temperature rose, the team found. An infrared image captured during their observing campaign in January, February and May of 2017 clearly shows hot spots near the poles, where Jupiter's auroras are. The scientists based their findings on observations by the Subaru Telescope, atop the summit of Mauna Kea in Hawaii, which is operated by the National Astronomical Observatory of Japan.

The telescope's Cooled Mid-Infrared Camera and Spectograph (COMICS) recorded thermal images - which capture areas of higher or lower temperatures - of Jupiter's stratosphere.

"Such heating and chemical reactions may tell us something about other planets with harsh environments, and even early Earth," said Yasumasa Kasaba of Tohoku University, who also worked on the observing team.

Title: Re: Astronomy Thread
Post by: Star One on 04/09/2019 11:16 am
An Ice Giant and Warped Disk? Weird Star's Mysteries Just Get Weirder (https://www.space.com/weird-star-mysteries-ice-giant-warped-disk.html)

Quote
For over a decade, a warped disk around a young star puzzled astronomers — but new research now suggests explanations for two of the star's perplexing mysteries.

A newly spotted second ring in the star system suggests that far away from the parent star, an ice giant is lurking beyond the realm of current detection technology. Researchers also discovered that only the smallest particles of the disk are warped, with larger material more evenly spread around the star.
Title: Re: Astronomy Thread
Post by: Star One on 04/17/2019 04:52 pm
Possible evidence of an extrasolar object striking the Earth in 2014 (https://m.phys.org/news/2019-04-evidence-extrasolar-earth.html)

Quote
A pair of researchers has found possible evidence of an extrasolar object striking the Earth back in 2014. In their paper uploaded to the arXiv preprint server, Amir Siraj and Abraham Loeb describe their study of data in the Center for Near-Earth Object studies database and what they found.

Quote
Loeb and Siraj had reasoned that space objects traveling faster than normal might be evidence enough of an extrasolar visitor. That led to them to perform searches in the Center for Near-Earth Object studies database for objects that traveled faster than normal. They report that they found three hits, two of which they dismissed because of incomplete data. The third described a meteor that was believed to be slightly less than a meter wide that had been observed disintegrating in the atmosphere on January 8th, 2014, at a height of 18.7 kilometers near Papua New Guinea. Its speed had been measured by a government sensor at 216,000 km/h. By looking at its trajectory and tracing backward, the researchers report that it likely came from somewhere outside of our solar system. If the evidence pans out, the sighting would be the first known instance of an extrasolar object striking the Earth.
Title: Re: Astronomy Thread
Post by: Star One on 04/17/2019 08:42 pm
 Explosion on Jupiter-sized star 10 times more powerful than ever seen on our Sun (https://www.eurekalert.org/pub_releases/2019-04/uow-eoj041719.php)

Quote
A stellar flare ten times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter.

The star is the coolest and smallest to give off a rare white-light superflare, and by some definitions could be too small be considered a star.

Title: Re: Astronomy Thread
Post by: Star One on 04/17/2019 09:04 pm
A New Signal for a Neutron Star Collision Discovered
For Release: April 16, 2019

NASA/CXC

A bright burst of X-rays has been discovered by NASA's Chandra X-ray Observatory in a galaxy 6.6 billion light years from Earth. This event likely signaled the merger of two neutron stars and could give astronomers fresh insight into how neutron stars — dense stellar objects packed mainly with neutrons — are built.

When two neutron stars merge they produce jets of high energy particles and radiation fired in opposite directions. If the jet is pointed along the line of sight to the Earth, a flash, or burst, of gamma rays can be detected. If the jet is not pointed in our direction, a different signal is needed to identify the merger.

The detection of gravitational waves — ripples in spacetime — is one such signal. Now, with the observation of a bright flare of X-rays, astronomers have found another signal, and discovered that two neutron stars likely merged to form a new, heavier and fast-spinning neutron star with an extraordinarily strong magnetic field.

"We've found a completely new way to spot a neutron star merger," said Yongquan Xue of the University of Science and Technology of China and lead author of a paper appearing in Nature. "The behavior of this X-ray source matches what one of our team members predicted for these events."

Chandra observed the source, dubbed XT2, as it suddenly appeared and then faded away after about seven hours.The source is located in the Chandra Deep Field-South, the deepest X-ray image ever taken that contains almost 12 weeks of Chandra observing time, taken at various intervals over several years. The source appeared on March 22nd, 2015 and was discovered later in analysis of archival data.

"The serendipitous discovery of XT2 makes another strong case that nature's fecundity repeatedly transcends human imagination,"said co-author Niel Brandt of the PennsylvaniaState University and principal investigator of the relevant Chandra Deep Field-South.

The researchers identified the likely origin of XT2 by studying how its X-ray light varied with time, and comparing this behavior with predictions made in 2013 by Bing Zhang from the University of Nevada in Las Vegas, one of the corresponding authors of the paper. The X-rays showed a characteristic signature that matched those predicted for a newly-formed magnetar — a neutron star spinning around hundreds of times per second and possessing a tremendously strong magnetic field about a quadrillion times that of Earth's.

The team think that the magnetar lost energy in the form of an X-ray-emitting wind, slowing down its rate of spin as the source faded. The amount of X-ray emission stayed roughly constant in X-ray brightness for about 30 minutes, then decreased in brightness by more than a factor of 300 over 6.5 hours before becoming undetectable. This showed that the neutron star merger produced a new, larger neutron star and not a black hole.

This result is important because it gives astronomers a chance to learn about the interior of neutron stars, objects that are so dense that their properties could never be replicated on Earth.

"We can't throw neutron stars together in a lab to see what happens, so we have to wait until the Universe does it for us," said Zhang. "If two neutron stars can collide and a heavy neutron star survives, then this tells us that their structure is relatively stiff and resilient."

Neutron star mergers have been prominent in the news since the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from one in 2017. That source, known as GW170817, produced a burst of gamma rays and an afterglow in light detected by many other telescopes, including Chandra. Xue's team think that XT2 would also have been a source of gravitational waves, however it occurred before Advanced LIGO started its first observing run, and it was too distant to have been detected in any case.

Xue's team also considered whether the collapse of a massive star could have caused XT2, rather than a neutron star merger. The source is in the outskirts of its host galaxy, which aligns with the idea that supernova explosions that left behind the neutron stars kicked them out of the center a few billion years earlier. The galaxy itself also has certain properties — including a low rate of star formation compared to other galaxies of a similar mass — that are much more consistent with the type of galaxy where the merger of two neutron stars is expected to occur.Massive stars are young and are associated with high rates of star formation.

"The host-galaxy properties of XT2 indeed boost our confidence in explaining its origin,"said co-author Ye Li from Peking University.

The team estimated the rate at which events like XT2 should occur, and found that it agrees with the rate deduced from the detection of GW170817. However, both estimates are highly uncertain because they depend on the detection of just one object each, so more examples are needed.

"We've started looking at other Chandra data to see if similar sources are present", said co-author Xuechen Cheng, also of the University of Science and Technology of China. "Just as with this source, the data sitting in archives might contain some unexpected treasures."

A paper describing these results appeared in the April 11thissue of Nature. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.


Other materials about the findings are available at:
http://chandra.si.edu

For more Chandra images, multimedia and related materials, visit:
http://www.nasa.gov/chandra
Title: Re: Astronomy Thread
Post by: Star One on 04/22/2019 08:09 am
The Weird Detector - Cool Worlds

Detecting the unusual in large datasets using algorithms.

[media=youtube]https://youtu.be/ZtrBi4QiFW0[/media]
Title: Re: Astronomy Thread
Post by: Star One on 04/24/2019 08:28 pm
 Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System (https://arxiv.org/abs/1904.07255)

Of the nine confirmed transiting circumbinary planet systems, only Kepler-47 is known to contain more than one planet. Kepler-47 b (the "inner planet") has an orbital period of 49.5 days and a radius of about 3R⊕. Kepler-47 c (the "outer planet") has an orbital period of 303.2 days and a radius of about 4.7R⊕. Here we report the discovery of a third planet, Kepler-47 d (the "middle planet"), which has an orbital period of 187.4 days and a radius of about 7R⊕. The presence of the middle planet allows us to place much better constraints on the masses of all three planets, where the 1σ ranges are less than 26M⊕, between 7−43M⊕, and between 2−5M⊕ for the inner, middle, and outer planets, respectively. The middle and outer planets have low bulk densities, with ρmiddle&lt;0.68 g cm−3 and ρouter&lt;0.26 g cm−3 at the 1σ level. The two outer planets are "tightly packed," assuming the nominal masses, meaning no other planet could stably orbit between them. All of the orbits have low eccentricities and are nearly coplanar, disfavoring violent scattering scenarios and suggesting gentle migration in the protoplanetary disk.
Title: Re: Astronomy Thread
Post by: Star One on 04/25/2019 08:55 pm
Rapid destruction of Earth-like atmospheres by young stars (https://www.sciencedaily.com/releases/2019/04/190424102244.htm)

Quote
The discoveries of thousands of planets orbiting stars outside our solar system has made questions about the potential for life to form on these planets. Fundamentally important for the habitability of a planet is whether or not it can hold onto an atmosphere. A new study by has shown that young stars can rapidly destroy the atmospheres of Earth-like planets, which is a significant additional difficulty for the formation of life outside our solar system.
Title: Re: Astronomy Thread
Post by: Star One on 04/26/2019 06:38 am
Not a detection of dark matter but more a validation of such detectors abilities to detect rare events.

Observation of two-neutrino double electron capture in 124Xe with XENON1T (https://www.nature.com/articles/s41586-019-1124-4)

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Two-neutrino double electron capture (2νECEC) is a second-order weak-interaction process with a predicted half-life that surpasses the age of the Universe by many orders of magnitude1. Until now, indications of 2νECEC decays have only been seen for two isotopes2,3,4,5, 78Kr and 130Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance6,7. The 2νECEC half-life is an important observable for nuclear structure models8,9,10,11,12,13,14 and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass15,16,17. Here we report the direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector. The significance of the signal is 4.4 standard deviations and the corresponding half-life of 1.8 × 1022 years (statistical uncertainty, 0.5 × 1022 years; systematic uncertainty, 0.1 × 1022 years) is the longest measured directly so far. This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments18,19,20.
Title: Re: Astronomy Thread
Post by: RotoSequence on 04/26/2019 06:50 am
https://arxiv.org/abs/1903.07603

Quote
Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM

Adam G. Riess, Stefano Casertano, Wenlong Yuan, Lucas M. Macri, Dan Scolnic

We present an improved determination of the Hubble constant (H0) from Hubble Space Telescope (HST) observations of 70 long-period Cepheids in the Large Magellanic Cloud. These were obtained with the same WFC3 photometric system used to measure Cepheids in the hosts of Type Ia supernovae. Gyroscopic control of HST was employed to reduce overheads while collecting a large sample of widely-separated Cepheids. The Cepheid Period-Luminosity relation provides a zeropoint-free link with 0.4% precision between the new 1.2% geometric distance to the LMC from Detached Eclipsing Binaries (DEBs) measured by Pietrzynski et al (2019) and the luminosity of SNe Ia. Measurements and analysis of the LMC Cepheids were completed prior to knowledge of the new LMC distance. Combined with a refined calibration of the count-rate linearity of WFC3-IR with 0.1% precision (Riess et al 2019), these three improved elements together reduce the full uncertainty in the LMC geometric calibration of the Cepheid distance ladder from 2.5% to 1.3%. Using only the LMC DEBs to calibrate the ladder we find H0=74.22 +/- 1.82 km/s/Mpc including systematic uncertainties, 3% higher than before for this particular anchor. Combining the LMC DEBs, masers in NGC 4258 and Milky Way parallaxes yields our best estimate: H0 = 74.03 +/- 1.42 km/s/Mpc, including systematics, an uncertainty of 1.91%---15% lower than our best previous result. Removing any one of these anchors changes H0 by < 0.7%. The difference between H0 measured locally and the value inferred from Planck CMB+LCDM is 6.6+/-1.5 km/s/Mpc or 4.4 sigma (P=99.999% for Gaussian errors) in significance, raising the discrepancy beyond a plausible level of chance. We summarize independent tests which show this discrepancy is not readily attributable to an error in any one source or measurement, increasing the odds that it results from a cosmological feature beyond LambdaCDM.
Title: Re: Astronomy Thread
Post by: Star One on 04/30/2019 11:09 am
Scientists Planning Now for Asteroid Flyby a Decade Away (https://www.jpl.nasa.gov/news/news.php?feature=7390)

On April 13, 2029, a speck of light will streak across the sky, getting brighter and faster. At one point it will travel more than the width of the full Moon within a minute and it will get as bright as the stars in the Little Dipper. But it won't be a satellite or an airplane - it will be a 1,100-foot-wide (340-meter-wide) near-Earth asteroid called 99942 Apophis that will cruise harmlessly by Earth, about 19,000 miles (31,000 kilometers) above the surface. That's within the distance that some of our spacecraft that orbit Earth.

The international asteroid research community couldn't be more excited.

This week at the 2019 Planetary Defense Conference in College Park, Maryland, scientists are gathering to discuss observation plans and science opportunities for the celestial event still a decade away. During a session on April 30, scientists will discuss everything from how to observe the event to hypothetical missions we could send out to the asteroid.

"The Apophis close approach in 2029 will be an incredible opportunity for science," said Marina Brozovi?, a radar scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, who works on radar observations of near-Earth objects (NEOs). "We'll observe the asteroid with both optical and radar telescopes. With radar observations, we might be able to see surface details that are only a few meters in size."

It's rare for an asteroid of this size to pass by Earth so close. Although scientists have spotted small asteroids, on the order of 5-10 meters, flying by Earth at a similar distance, asteroids the size of Apophis are far fewer in number and so do not pass this close to Earth as often.

The asteroid, looking like a moving star-like point of light, will first become visible to the naked eye in the night sky over the Southern Hemisphere, flying above Earth from the east coast to the west coast of Australia. It will be mid-morning on the East Coast of the United States when Apophis is above Australia. It will then cross the Indian Ocean, and by the afternoon in the eastern U.S. it will have crossed the equator, still moving west, above Africa. At closest approach, just before 6 p.m. EDT, Apophis will be over the Atlantic Ocean - and it will move so fast that it will cross the Atlantic in just an hour. By 7 p.m. EDT, the asteroid will have crossed over the United States.

A team of astronomers at the Kitt Peak National Observatory discovered Apophis in June 2004. The astronomers were only able to detect the asteroid for two days before technical and weather issues prevented further observations. Luckily, another team rediscovered the asteroid at the Siding Spring Survey in Australia later that year. The observations caused quite a stir - initial orbital calculations revealed that the asteroid had a 2.7% chance of impacting Earth in 2029. Fortunately, additional observations completely ruled out that possibility.

Since its discovery, optical and radar telescopes have tracked Apophis as it continues on its orbit around the Sun, so we know its future trajectory quite well. Current calculations show that Apophis still has a small chance of impacting Earth, less than 1 in 100,000 many decades from now, but future measurements of its position can be expected to rule out any possible impacts.

The most important observations of Apophis will occur in 2029, when asteroid scientists around the world will have an opportunity to conduct a close-up study of the Apophis' size, shape, composition and possibly even its interior.

At the conference, scientists will discuss questions like "How will Earth's gravity affect the asteroid as it passes by?," "Can we use Apophis' flyby to learn about an asteroid's interior?" and "Should we send a spacecraft mission to Apophis?"

"We already know that the close encounter with Earth will change Apophis' orbit, but our models also show the close approach could change the way this asteroid spins, and it is possible that there will be some surface changes, like small avalanches," said Davide Farnocchia, an astronomer at JPL's Center for Near Earth Objects Studies (CNEOS), who is co-chairing the April 30 session on Apophis with Brozovi?.

"Apophis is a representative of about 2,000 currently known Potentially Hazardous Asteroids (PHAs)," said Paul Chodas, director of CNEOS. "By observing Apophis during its 2029 flyby, we will gain important scientific knowledge that could one day be used for planetary defense."
Title: Re: Astronomy Thread
Post by: Star One on 05/01/2019 08:02 am
One-Third of Exoplanets Could Be Water Worlds With Oceans Hundreds of Miles Deep (https://www.smithsonianmag.com/smart-news/exoplanets-could-be-ocean-covered-water-worlds-180972068/)

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Rovers on Mars are looking for present-day water or ice as well as signs of ancient rivers and oceans. They’ve scoured the moon looking for signs of ice deep in its craters and even sent a probe to look for ice on a comet. But new research suggests finding cosmic H2O may not be all that difficult outside our own solar system. Simulations based on exoplanet data suggest water worlds covered with deep oceans may actually be rather common throughout our galaxy, according to a new study published this week in PNAS.
Title: Re: Astronomy Thread
Post by: Star One on 05/03/2019 10:36 am
I’ve posted this here as I can’t find an update thread for the mission.

ASU researchers find water in samples from asteroid Itokawa (https://asunow.asu.edu/20190501-discoveries-asu-researchers-find-water-in-asteroid-itokawa-samples)

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Two cosmochemists at Arizona State University have made the first-ever measurements of water contained in samples from the surface of an asteroid. The samples came from asteroid Itokawa and were collected by the Japanese space probe Hayabusa.

The team's findings suggest that impacts early in Earth's history by similar asteroids could have delivered as much as half of our planet's ocean water.

"We found the samples we examined were enriched in water compared to the average for inner solar system objects," Ziliang Jin said. A postdoctoral scholar in ASU's School of Earth and Space Exploration, Jin is the lead author on the paper published May 1 in Science Advances reporting the results. His co-author is Maitrayee Bose, assistant professor in the school.

Title: Re: Astronomy Thread
Post by: Star One on 05/03/2019 12:42 pm
An Exomoon Eludes Astronomers—for Now (https://www.scientificamerican.com/article/an-exomoon-eludes-astronomers-for-now/)

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Reports of an exomoon’s death may have been greatly exaggerated. In late April, a trio of astronomers suggested that the best-yet candidate for an exomoon—a moon orbiting a world in another planetary system—does not actually exist, being instead a statistical mirage. The candidate’s original discoverers disagree, saying the case is anything but closed. For now, alas, the debate is at an impasse: One way or the other, definitive proof for or against this exomoon may be years away.

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Now a new twist has emerged, via another independent analysis by Laura Kreidberg from the Harvard-Smithsonian Center for Astrophysics in Massachusetts and colleagues. In a paper posted on the pre-print server arXiv, they re-examine the Hubble data used by Teachey and Kipping, finding no evidence for a second dip in the star’s light at all. “I’m not convinced that this particular exomoon is real,” says Kreidberg. She thinks Teachey and Kipping were mistaken in their original analysis, and that efforts would be better placed looking for exomoon candidates around other stars. The discrepancy arises from the fact that Hubble observations struggle to reach the necessary levels of precision required to distinguish between random fluctuations (in starlight or in instrumental performance) and the faint-but-genuine signal that would be associated with even the largest conceivable exomoons. Discerning the difference is a matter of guesswork using sophisticated, computationally intensive numerical models.

I am guessing papers like the above played a part in the denial of more observing time on Hubble.

Quote
Unfortunately, attempts to use Hubble again to observe this system have been in vain; Teachey and Kipping’s request for further time on the telescope to study the next predicted transit of Kepler-1625b and its potential exomoon in May 2019 was recently denied. “There’s always stiff competition for observing time on Hubble,” says Neill Reid, the associate director for science at the Baltimore-based Space Telescope Science Institute, the organization responsible for allocating time on Hubble. “There’s always twice as many proposals that [we] would like to see get observations than we have orbits to support.” The failure to secure additional Hubble time is problematic, Kipping notes, because subsequent transits of the potential exomoon become much more difficult to predict the further off they occur in the future.
Title: Re: Astronomy Thread
Post by: Star One on 05/04/2019 02:11 pm
A rapidly changing jet orientation in the stellar-mass black-hole system V404 Cygni (https://www.nature.com/articles/s41586-019-1152-0)

Powerful relativistic jets are one of the main ways in which accreting black holes provide kinetic feedback to their surroundings. Jets launched from or redirected by the accretion flow that powers them are expected to be affected by the dynamics of the flow, which for accreting stellar-mass black holes has shown evidence for precession1 due to frame-dragging effects that occur when the black-hole spin axis is misaligned with the orbital plane of its companion star2. Recently, theoretical simulations have suggested that the jets can exert an additional torque on the accretion flow3, although the interplay between the dynamics of the accretion flow and the launching of the jets is not yet understood. Here we report a rapidly changing jet orientation—on a time scale of minutes to hours—in the black-hole X-ray binary V404 Cygni, detected with very-long-baseline interferometry during the peak of its 2015 outburst. We show that this changing jet orientation can be modelled as the Lense–Thirring precession of a vertically extended slim disk that arises from the super-Eddington accretion rate4. Our findings suggest that the dynamics of the precessing inner accretion disk could play a role in either directly launching or redirecting the jets within the inner few hundred gravitational radii. Similar dynamics should be expected in any strongly accreting black hole whose spin is misaligned with the inflowing gas, both affecting the observational characteristics of the jets and distributing the black-hole feedback more uniformly over the surrounding environment5,6.
Title: Astronomy Thread
Post by: Star One on 05/06/2019 04:17 pm
 'Oumuamua's Cousin? (https://blogs.scientificamerican.com/observations/oumuamuas-cousin/)

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The trajectory of the fastest object ended up being bound to the sun since it involved a head-on collision with the moving Earth. The second fastest was definitely unbound to the sun. The third fastest was possibly bound within uncertainties. The surprising result about the second fastest meteor in the catalog was conveyed through a surprising e-mail from Amir saying: “We might have discovered the first meteor which originated outside the solar system!” A few days later, we posted   our paper on the arXiv (https://www.cfa.harvard.edu/~loeb/1904.07224.pdf) and simultaneously submitted it for publication in Astrophysical Journal Letters.
There is an important moral to this story. Media appearances are not a waste of time. They can raise questions that inspire scientific breakthroughs.

SCHRÖDINGER'S GAS: MARS BOTH HAS AND DOES NOT HAVE METHANE IN ITS ATMOSPHERE (https://www.syfy.com/syfywire/schrodingers-gas-mars-both-has-and-does-not-have-methane-in-its-atmosphere)

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Does the atmosphere of Mars have methane in it or not?

This is a question that planetary scientists have been asking for years, and the answer, maddeningly is: Yes. No. Maybe. Well…

A tectonic plate may have peeled apart—and that could shrink the Atlantic Ocean (https://www.nationalgeographic.com/science/2019/05/tectonic-plate-peeled-apart-could-shrink-atlantic-ocean-geology/)

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For years, João Duarte has puzzled over a seemingly boring underwater expanse off the coast of Portugal. In 1969, this site spawned a massive earthquake that rattled the shore and sparked a tsunami. But you would never know why just from looking at the broad, featureless surface of the seabed. Duarte, a marine geologist from the Instituto Dom Luiz at the University of Lisbon, wanted to find out what was going on.

Now, 50 years after the event, he may finally have an answer: The bottom of the tectonic plate off Portugal's coast seems to be peeling away from its top. This action may be providing the necessary spark for one plate to start grinding beneath another in what's known as a subduction zone, according to computer simulations Duarte presented in April at the European Geosciences Union meeting.
Title: Re: Astronomy Thread
Post by: Star One on 05/07/2019 08:16 pm
Blue supergiant stars open doors to concert in space (https://www.sciencedaily.com/releases/2019/05/190506124121.htm)

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Blue supergiants are rock-and-roll: they live fast and die young. This makes them rare and difficult to study. Before space telescopes were invented, few blue supergiants had been observed, so our knowledge of these stars was limited. Astronomers have now studied the sounds originating inside these stars and discovered that almost all blue supergiants shimmer in brightness because of waves on their surface.
Title: Re: Astronomy Thread
Post by: eeergo on 05/08/2019 10:09 am
First phase of ground telescope for high-energy cosmic gamma rays (LHASSO) has been inaugurated in the Tibetan plateau:

https://www.nature.com/articles/d41586-019-01467-1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/08/2019 02:04 pm
YELLOWSTONE SUPERVOLCANO HAD ERUPTIVE EPISODES WITH 'HIGHLY CLUSTERED' LAVA FLOWS (https://www.newsweek.com/yellowstone-eruption-history-clustered-1418952)

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The Yellowstone supervolcano produced a huge eruption around 613,000 years ago, where it ejected 240 cubic miles of material. That’s over double the volume of Lake Erie, and 2,500 times bigger than the 1980 eruption of Mt. St. Helens.

However, since then the volcano has produced many more smaller eruptions of rhyolite (igneous, volcanic rock) lava flows.

Scientists with the U.S. Geological Survey’s volcano observatories are now working to better understand these smaller events in order to understand the hazards posed by the magmatic system at Yellowstone.

Yellowstone has produced at least 28 rhyolite eruptions over the last 610,000 years, a statement from California Volcano Observatory said. These were not small eruptions, producing lava flows ranging from 0.1 to 17 cubic miles—in comparison, Mt. St. Helen’s produced 0.06 cubic miles of material.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/08/2019 02:06 pm
Change in thread title to better reflect the contents of the thread, and also include Earth sciences under the planetary definition.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/08/2019 07:53 pm
Bizarre form of hot ice seen on Earth (https://www.nationalgeographic.com/science/2019/05/bizarre-hot-ice-xviii-seen-on-earth-superionic-uranus-neptune/)

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Now, researchers have snapped x-ray images of what might be the newest entrant to ice’s diversity: a highly electrically conductive material known as superionic ice. As the team reports today in the journal Nature, this ice exists at pressures between one and four million times that at sea level and temperatures half as hot as the surface of the sun.

“Yes, we’re talking about ice,” says study leader Marius Millot, a physicist at Lawrence Livermore National Laboratory in California. “But the sample is at several thousand degrees.”

While normally unachievable on Earth, such conditions should be present deep inside the watery giants Uranus and Neptune, potentially helping to explain how these distant planets work, including the origins of their unusual magnetic fields.

Quote
Neptune’s magnetic field, by contrast, seems to come from an internal bar magnet that has drifted down to one side, with its ends emerging from spots halfway to the equator. Uranus’ is even more outlandish, like a bar magnet that has flipped upside-down, meaning its magnetic south juts out from the planet’s northern hemisphere. Both ice giants’ magnetic fields are suspected of being unstable.

Millot has suggested that there could be a liquid layer at the top edge of Uranus and Neptune’s superionic ice layer, but that it is also a highly electrically conductive phase of water. The planets’ magnetic fields might originate here, far closer to the surface than the magnetic fields of other worlds, potentially explaining their wonky characteristics. And since astronomers have discovered many Neptune and Uranus-sized exoplanets, the findings could be applicable to far-flung parts of the cosmos.

A nearby neutron-star merger explains the actinide abundances in the early Solar System (https://www.nature.com/articles/s41586-019-1113-7)

A growing body of evidence indicates that binary neutron-star mergers are the primary origin of heavy elements produced exclusively through rapid neutron capture1,2,3,4 (the ‘r-process’). As neutron-star mergers occur infrequently, their deposition of radioactive isotopes into the pre-solar nebula could have been dominated by a few nearby events. Although short-lived r-process isotopes—with half-lives shorter than 100 million years—are no longer present in the Solar System, their abundances in the early Solar System are known because their daughter products were preserved in high-temperature condensates found in meteorites5. Here we report that abundances of short-lived r-process isotopes in the early Solar System point to their origin in neutron-star mergers, and indicate substantial deposition by a single nearby merger event. By comparing numerical simulations with the early Solar System abundance ratios of actinides produced exclusively through the r-process, we constrain the rate of occurrence of their Galactic production sites to within about 1−100 per million years. This is consistent with observational estimates of neutron-star merger rates6,7,8, but rules out supernovae and stellar sources. We further find that there was probably a single nearby merger that produced much of the curium and a substantial fraction of the plutonium present in the early Solar System. Such an event may have occurred about 300 parsecs away from the pre-solar nebula, approximately 80 million years before the formation of the Solar System.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/11/2019 08:16 am
A Star in the Big Dipper Is an Alien Invader (https://www.livescience.com/65452-weirdo-star-from-another-galaxy.html)

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A star in the Big Dipper is an intergalactic alien, according to clues in its chemical fingerprints.

The star's unusual chemistry is unlike that of all known stars in the Milky Way and instead has more in common with stars in nearby dwarf galaxies, new research reveals.

Researchers suspected that the stellar oddball, named J1124+4535, originated in a dwarf galaxy that collided with the Milky Way long ago. According to that theory, when the dwarf galaxy fell apart, it stranded this star in our cosmic neighborhood.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/11/2019 08:06 pm
 Why This Martian Full Moon Looks Like Candy (https://www.jpl.nasa.gov/news/news.php?feature=7398)

For the first time, NASA's Mars Odyssey orbiter has caught the Martian moon Phobos during a full moon phase. Each color in this new image represents a temperature range detected by Odyssey's infrared camera, which has been studying the Martian moon since September of 2017. Looking like a rainbow-colored jawbreaker, these latest observations could help scientists understand what materials make up Phobos, the larger of Mars' two moons.

Odyssey is NASA's longest-lived Mars mission. Its heat-vision camera, the Thermal Emission Imaging System (THEMIS), can detect changes in surface temperature as Phobos circles Mars every seven hours. Different textures and minerals determine how much heat THEMIS detects.

"This new image is a kind of temperature bullseye - warmest in the middle and gradually cooler moving out," said Jeffrey Plaut, Odyssey project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, which leads the mission. "Each Phobos observation is done from a slightly different angle or time of day, providing a new kind of data."

On April 24, 2019, THEMIS looked at Phobos dead-on, with the Sun behind the spacecraft. This full moon view is better for studying material composition, whereas half-moon views are better for looking at surface textures.

"With the half-moon views, we could see how rough or smooth the surface is and how it's layered," said Joshua Bandfield, a THEMIS co-investigator and senior research scientist at the Space Sciences Institute in Boulder, Colorado. "Now we're gathering data on what minerals are in it, including metals."

Iron and nickel are two such metals. Depending on how abundant the metals are, and how they're mixed with other minerals, these data could help determine whether Phobos is a captured asteroid or a pile of Mars fragments, blasted into space by a giant impact long ago.

These recent observations won't definitively explain Phobos' origin, Bandfield added. But Odyssey is collecting vital data on a moon scientists still know little about - one that future missions might want to visit. Human exploration of Phobos has been discussed in the space community as a distant, future possibility, and a Japanese sample-return mission to the moon is scheduled for launch in the 2020s.

"By studying the surface features, we're learning where the rockiest spots on Phobos are and where the fine, fluffy dust is," Bandfield said. "Identifying landing hazards and understanding the space environment could help future missions to land on the surface."

Odyssey has been orbiting Mars since 2001. It takes thousands of images of the Martian surface each month, many of which help scientists select landing sites for future missions. The spacecraft also serves an important role relaying data for Mars' newest inhabitant, NASA's InSight lander. But studying Phobos is a new chapter for the orbiter.

"I think it's a great example of taking a spacecraft that's been around a very long time and finding new things you can do with it," Bandfield said. "It's great that you can still use this tool to collect groundbreaking science."

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Science Mission Directorate in Washington. THEMIS was developed by Arizona State University in Tempe in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Philip Christensen at Arizona State University. The prime contractor for the Odyssey project, Lockheed Martin Space in Denver, developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of Caltech in Pasadena.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/15/2019 04:27 pm
 A BLACK HOLE IN A DISTANT GALAXY HAS BEEN EATING A STAR… FOR MORE THAN A *DECADE* (https://www.syfy.com/syfywire/a-black-hole-in-a-distant-galaxy-has-been-eating-a-star-for-more-than-a-decade)

Quote
In a distant galaxy, a staggering 1.8 billion light years from Earth, a black hole is eating a star.

This is a colossal, titanic event; the gravity from the black hole literally rips the star apart and consumes the entrails, generating soul-vaporizing amounts of energy in the process. We’ve seen this sort of thing before, many times in fact… but this one is special. This black hole has been savoring its meal, munching away at the star for well over a decade.

The galaxy is prosaically called 3XMM J150052.0+015452 (let’s call it J150052 for short). It’s a dwarf galaxy, much smaller than the Milky Way, with a total mass of about 6 billion times the Sun’s (the Milky Way’s mass is over 100 times larger). It’s a starburst galaxy, meaning it’s not only actively making stars, but doing so quite vigorously.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/15/2019 10:22 pm
Something Strange Punched a Hole in the Milky Way. But What Exactly Is It? (https://www.livescience.com/65483-dark-impactor-could-be-dark-matter.html)

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There's a "dark impactor" blasting holes in our galaxy. We can't see it. It might not be made of normal matter. Our telescopes haven't directly detected it. But it sure seems like it's out there.

"It's a dense bullet of something," said Ana Bonaca, a researcher at the Harvard-Smithsonian Center for Astrophysics, who discovered evidence for the impactor.

Bonaca's evidence for the dark impactor, which she presented April 15 at the conference of the American Physical Society in Denver, is a series of holes in our galaxy's longest stellar stream, GD-1. Stellar streams are lines of stars moving together across galaxies, often originating in smaller blobs of stars that collided with the galaxy in question. The stars in GD-1, remnants of a "globular cluster" that plunged into the Milky Way a long time ago, are stretched out in a long line across our sky.

TESS Spots a Compact System of Super-Earths around the Naked-Eye Star HR 858 (https://arxiv.org/abs/1905.05193)

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Transiting Exoplanet Survey Satellite (TESS) observations have revealed a compact multi-planet system around the sixth-magnitude star HR 858 (TIC 178155732), located 32 parsecs away. Three planets, each about twice the size of Earth, transit this slightly-evolved, late F-type star, which is also a member of a visual binary. Two of the planets may be in mean motion resonance. We analyze the TESS observations, using novel methods to model and remove instrumental systematic errors, and combine these data with follow-up observations taken from a suite of ground-based telescopes to characterize the planetary system. The HR 858 planets are enticing targets for precise radial velocity observations, secondary eclipse spectroscopy, and measurements of the Rossiter-McLaughlin effect.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/17/2019 04:19 pm
'Groundbreaking' Sharp Images of Distant Planetary System Show 3 Planets Are Missing (https://www.sciencealert.com/groundbreaking-sharp-images-of-a-protoplanetary-system-find-no-planets)

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Using the combined might of two of Hawaii's powerful telescopes, astronomers have captured what they are describing as "groundbreaking" sharp new images of a planetary system still in the process of being born.

They also found no evidence of three previously detected planets. The star is LkCa 15, a young, Sun-like T Tauri star 473 light-years away, and the missing planets are not a bad thing. Nor do they mean that no planets are forming.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/18/2019 07:36 am
The moon may be tectonically active, and geologists are shaken (https://www.nationalgeographic.com/science/2019/05/moon-may-be-tectonically-active-geologists-shaken-apollo-moonquakes/)

Quote
In a study out today in Nature Geoscience, researchers may have finally pinpointed the epicenters of mysterious moonquakes recorded by Apollo-era seismometers, and the tremors seem to originate from cliff-like features called fault scarps.

“The whole idea that a 4.6-billion-year-old rocky body like the moon has managed to stay hot enough in the interior and produce this network of faults just flies in the face of conventional wisdom,” says study coauthor Thomas Watters of the Smithsonian Institution in Washington, D.C.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/22/2019 09:21 am
A massive white-dwarf merger product before final collapse (https://www.nature.com/articles/s41586-019-1216-1)

Gravitational-wave emission can lead to the coalescence of close pairs of compact objects orbiting each other1,2. In the case of neutron stars, such mergers may yield masses above the Tolman–Oppenheimer–Volkoff limit (2 to 2.7 solar masses)3, leading to the formation of black holes4. For white dwarfs, the mass of the merger product may exceed the Chandrasekhar limit, leading either to a thermonuclear explosion as a type Ia supernova5,6 or to a collapse forming a neutron star7,8. The latter case is expected to result in a hydrogen- and helium-free circumstellar nebula and a hot, luminous, rapidly rotating and highly magnetized central star with a lifetime of about 10,000 years9,10. Here we report observations of a hot star with a spectrum dominated by emission lines, which is located at the centre of a circular mid-infrared nebula. The widths of the emission lines imply that wind material leaves the star with an outflow velocity of 16,000 kilometres per second and that rapid stellar rotation and a strong magnetic field aid the wind acceleration. Given that hydrogen and helium are probably absent from the star and nebula, we conclude that both objects formed recently from the merger of two massive white dwarfs. Our stellar-atmosphere and wind models indicate a stellar surface temperature of about 200,000 kelvin and a luminosity of about 104.6 solar luminosities. The properties of the star and nebula agree with models of the post-merger evolution of super-Chandrasekhar-mass white dwarfs9, which predict a bright optical and high-energy transient upon collapse of the star11 within the next few thousand years. Our observations indicate that super-Chandrasekhar-mass white-dwarf mergers can avoid thermonuclear explosion as type Ia supernovae, and provide evidence of the generation of magnetic fields in stellar mergers.

Here’s the related press release.

 Stellar waltz with dramatic ending (https://www.uni-bonn.de/news/119-2019)

Astronomers at the University of Bonn and their colleagues from Moscow have identified an unusual celestial object. It is most likely the product of the fusion of two stars that died a long time ago. After billions of years circling around each other these so-called white dwarfs merged and rose from the dead. In the near future, their lives could finally end - with a huge bang. The researchers are now presenting their findings in the journal Nature.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2019 06:22 am
New research at Bangor University helps shed light on the possibility of past life on Venus (https://www.bangor.ac.uk/news/latest/new-research-at-bangor-university-helps-shed-light-on-the-possibility-of-past-life-on-venus-40747)

Quote
Tides act to brake a planets rotation rate because of friction between the tidal currents and the sea floor. On Earth today, this braking changes the length of a day by about 20 seconds per million years. A new study by Mattias Green at Bangor University’s School of Ocean Sciences and colleagues at NASA and University of Washington have quantified this braking effect on ancient Venus. They show that the tides in a Venusian ocean would have been large enough to slow the rotation rate of Venus by tens of Earth days per million years if Venus was spinning more like Earth does today. This suggests that the tidal brake could have slowed down Venus to its current rotation state in 10-50 million years, and therefore taking it away from being habitable in a short time frame.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/28/2019 05:19 pm
 Exploding stars led to humans walking on two legs, radical study suggests (https://www.theguardian.com/science/2019/may/28/exploding-stars-led-humans-walking-on-two-legs-study)

Quote
According to the researchers, a series of stars in our corner of the Milky Way exploded in a cosmic riot that began about 7m years ago and continued for millions of years more. The supernovae blasted powerful cosmic rays in all directions. On Earth, the radiation arriving from the cataclysmic explosions peaked about 2.6m years ago.

The surge of radiation triggered a chain of events, the scientists argue. As cosmic rays battered the planet, they ionised the atmosphere and made it more conductive. This could have ramped up the frequency of lightning strikes, sending wildfires raging through African forests, and making way for grasslands, they write in the Journal of Geology. With fewer trees at hand in the aftermath, our ancient ancestors adapted, and those who walked upright thrived.

Quote
The researchers concede that more research is needed to understand if cosmic rays really do drive lightning. “If the lightning–cosmic ray connection turns out to be incorrect, this whole thing falls apart,” said Melott.
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 05/29/2019 03:41 am
Quote
The surge of radiation triggered a chain of events, the scientists argue. As cosmic rays battered the planet, they ionised the atmosphere and made it more conductive. This could have ramped up the frequency of lightning strikes, sending wildfires raging through African forests, and making way for grasslands, they write in the Journal of Geology. With fewer trees at hand in the aftermath, our ancient ancestors adapted, and those who walked upright thrived.

Obviously not as simple as that, as baboons - a species about as old as humans and which thrive in that kind of habitat - do not walk upright.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/29/2019 06:28 am
Quote
The surge of radiation triggered a chain of events, the scientists argue. As cosmic rays battered the planet, they ionised the atmosphere and made it more conductive. This could have ramped up the frequency of lightning strikes, sending wildfires raging through African forests, and making way for grasslands, they write in the Journal of Geology. With fewer trees at hand in the aftermath, our ancient ancestors adapted, and those who walked upright thrived.

Obviously not as simple as that, as baboons - a species about as old as humans and which thrive in that kind of habitat - do not walk upright.

Maybe I am being unfair here, but the whole theory does look a bit like they are really over-reaching on the causality of the whole thing.
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 05/29/2019 05:31 pm
Maybe I am being unfair here, but the whole theory does look a bit like they are really over-reaching on the causality of the whole thing.

The arxiv version of the paper is https://arxiv.org/abs/1903.01501

The link to human evolution (which I agree is very speculative) is discussed in only three sentences in the 20 page paper, but somehow the press has chosen that as the main point of the story.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/29/2019 06:02 pm
Astronomers find 'Forbidden' planet in 'Neptunian Desert' around its star (https://www.sciencedaily.com/releases/2019/05/190528193034.htm)

Quote
An exoplanet smaller than Neptune with its own atmosphere has been discovered in a region close to its star where no Neptune-sized planets would normally be found.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/29/2019 06:02 pm
Maybe I am being unfair here, but the whole theory does look a bit like they are really over-reaching on the causality of the whole thing.

The arxiv version of the paper is https://arxiv.org/abs/1903.01501

The link to human evolution (which I agree is very speculative) is discussed in only three sentences in the 20 page paper, but somehow the press has chosen that as the main point of the story.

Thanks for the clarification.
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 05/30/2019 12:55 am
The arxiv version of the paper is https://arxiv.org/abs/1903.01501

The link to human evolution (which I agree is very speculative) is discussed in only three sentences in the 20 page paper, but somehow the press has chosen that as the main point of the story.

Probably because it was mentioned in the five-sentence abstract! :)
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 05/30/2019 05:22 am
The arxiv version of the paper is https://arxiv.org/abs/1903.01501

The link to human evolution (which I agree is very speculative) is discussed in only three sentences in the 20 page paper, but somehow the press has chosen that as the main point of the story.

Probably because it was mentioned in the five-sentence abstract! :)

And it is the focus of the press release from lead author's university: https://news.ku.edu/2019/03/12/supernovae-zapped-earth-26-million-years-ago-researchers-wonder-if-they-prompted-human

So yeah, I was wrong to blame the press for hyping the theory, the authors seem to have done it themselves.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/30/2019 06:44 am
A Second Pleiades in the Sky (https://sites.psu.edu/astrowright/2019/05/29/a-second-pleiades-in-the-sky/)

Quote
So if these are so obvious, how could there be another one?  Answer: if they’re so spread out across the sky that no one noticed they were related!  Back in February Meingast et al. announced that they had spotted a group of hundreds of stars all moving in the same direction—but they were spread all out against the sky.  If you plot most of the sky out flat, here’s what they look like (in red):
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/30/2019 06:45 am
The arxiv version of the paper is https://arxiv.org/abs/1903.01501

The link to human evolution (which I agree is very speculative) is discussed in only three sentences in the 20 page paper, but somehow the press has chosen that as the main point of the story.

Probably because it was mentioned in the five-sentence abstract! :)

And it is the focus of the press release from lead author's university: https://news.ku.edu/2019/03/12/supernovae-zapped-earth-26-million-years-ago-researchers-wonder-if-they-prompted-human

So yeah, I was wrong to blame the press for hyping the theory, the authors seem to have done it themselves.

Drawing attention to their paper?
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/30/2019 03:04 pm
Observation of thermal Hawking radiation and its temperature in an analogue black hole (https://www.nature.com/articles/s41586-019-1241-0)

The entropy of a black hole1 and Hawking radiation2 should have the same temperature given by the surface gravity, within a numerical factor of the order of unity. In addition, Hawking radiation should have a thermal spectrum, which creates an information paradox3,4. However, the thermality should be limited by greybody factors5, at the very least6. It has been proposed that the physics of Hawking radiation could be verified in an analogue system7, an idea that has been carefully studied and developed theoretically8,9,10,11,12,13,14,15,16,17,18. Classical white-hole analogues have been investigated experimentally19,20,21, and other analogue systems have been presented22,23. The theoretical works and our long-term study of this subject15,24,25,26,27 enabled us to observe spontaneous Hawking radiation in an analogue black hole28. The observed correlation spectrum showed thermality at the lowest and highest energies, but the overall spectrum was not of the thermal form, and no temperature could be ascribed to it. Theoretical studies of our observation made predictions about the thermality and Hawking temperature29,30,31,32,33. Here we construct an analogue black hole with improvements compared with our previous setup, such as reduced magnetic field noise, enhanced mechanical and thermal stability and redesigned optics. We find that the correlation spectrum of Hawking radiation agrees well with a thermal spectrum, and its temperature is given by the surface gravity, confirming the predictions of Hawking’s theory. The Hawking radiation observed is in the regime of linear dispersion, in analogy with a real black hole, and the radiation inside the black hole is composed of negative-energy partner modes only, as predicted.

Associated article.

https://gizmodo.com/laboratory-black-hole-shows-stephen-hawking-was-right-1835097982
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/31/2019 06:33 am
https://www.cnet.com/news/see-the-restored-film-of-a-solar-eclipse-from-1900/

[MEDIA=youtube]q4jfPfMKBgU[/MEDIA]
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/31/2019 08:09 pm
Subaru Telescope captures 1800 exploding stars (https://www.eurekalert.org/pub_releases/2019-05/kift-stc053019.php)

By combining one of the world's most powerful digital cameras and a telescope capable of capturing a wider shot of the night sky compared to other big telescopes, a team of researchers from Japan have been able to identify about 1800 new supernovae, including 58 Type Ia supernovae 8 billion light years away, reports a new study released online on 30 May.

A supernova is the name given to an exploding star that has reached the end of its life. The star often becomes as bright as its host galaxy, shining one billion times brighter than the Sun for anytime between a month to six months before dimming down. Supernova classed as Type Ia are useful because their constant maximum brightness allows researchers to calculate how far the star is from Earth. This is particularly useful for researchers who want to measure the expansion of the Universe.

In recent years, researchers began reporting a new type of supernovae five to ten times brighter than Type Ia supernovae. Named Super Luminous Supernovae, many have been trying to learn more about these stars. Their unusual brightness enables researchers to spot stars in the farthest parts of the Universe usually too faint to observe. Since distant Universe means the early Universe, studying this kind of star could reveal characteristics about the first, massive stars created after the Big Bang.

But supernovae are rare events, and there are only a handful of telescopes in the world capable of capturing sharp images of distant stars. In order to maximize the chances of observing a supernova, a team led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Professor Naoki Yasuda, and researchers from Tohoku University, Konan University, the National Astronomical Observatory of Japan, School of Science, the University of Tokyo, and Kyoto University, used the Subaru Telescope.

This telescope is capable of generating shape stellar images, and the Hyper Suprime-Cam, an 870 mega-pixel digital camera attached at its top, captures a very wide area of the night sky in one shot.

By taking repeated images of the same area of night sky over a six month period, the researchers could identify new supernovae by looking for stars that suddenly appeared brighter before gradually fading out.

As a result, the team identified 5 super luminous supernovae, and about 400 Type Ia supernovae. Fifty-eight of these Type Ia supernovae were located more than 8 billion light years away from Earth. In comparison, it took researchers using the Hubble Space Telescope about 10 years to discover a total of 50 supernovae located more than 8 billion light years away from Earth.

"The Subaru Telescope and Hyper Suprime-Cam have already helped researchers create a 3D map of dark matter, and observation of primordial black holes, but now this result proves that this instrument has a very high capability finding supernovae very, very far away from Earth. I want to thank all of my collaborators for their time and effort, and look forward to analyzing our data to see what kind of picture of the Universe it holds," said Yasuda.

The next step will be to use the data to calculate a more accurate expansion of the Universe, and to study how dark energy has changed over time.

Details of the study were published by the Publications of the Astronomical Society of Japan.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/03/2019 01:33 pm
AN AMATEUR ASTRONOMER HAS DISCOVERED A NEARBY GALAXY! (https://www.syfy.com/syfywire/an-amateur-astronomer-has-discovered-a-nearby-galaxy)

Quote
Donatiello I is just such a beast, so faint that it would be incredibly easy to overlook even in deep images taken by meter-class telescopes. And that's why this story is so cool. Donatiello I is named for Giuseppe Donatiello, the amateur astronomer who discovered it.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/03/2019 09:25 pm
Giant stellar eruption detected for the first time (https://m.phys.org/news/2019-06-giant-stellar-eruption.html)

Quote
A group of researchers has identified and characterized for the first time in a complete way a powerful eruption in the atmosphere of the active star HR 9024, marked by an intense flash of X-rays followed by the emission of a giant bubble of plasma, ie hot gas containing charged particles. This is the first time a coronal mass ejection, or CME, has been seen in a star other than our Sun. The corona is the outer atmosphere of a star.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/04/2019 06:50 am
Direct Images Show Baby Exoplanets Stealing Gas From Their Parent Star (http://blogs.discovermagazine.com/d-brief/2019/06/03/direct-images-show-baby-exoplanets-stealing-gas-from-their-parent-star/)

Quote
While discoveries of exoplanets are commonplace these days, the most obvious detection method – directly taking a picture of a planet – remains one of the most challenging. And such images almost always reveal a single, giant planet orbiting far from its host star.

So researchers were pleasantly surprised to turn up a second planet orbiting around PDS 70, a young star system about 370 light-years away from Earth. It’s only the second multi-planet system observed by direct imaging, and the image shows the star system still in formation, providing valuable evidence about how planetary systems form and evolve.

Flashes on the Moon (https://www.uni-wuerzburg.de/en/news-and-events/news/detail/news/flashes-on-the-moon/)

Quote
On the moon flashes and other enigmatic light phenomena can be observed again and again. With a new telescope, a professor at the University of Würzburg wants to get to the bottom of these phenomena.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/04/2019 04:59 pm
NASA'S HUBBLE CAPTURES BIZARRE GALAXY HURTLING TOWARDS THE MILKY WAY (https://www.newsweek.com/nasas-hubble-captures-bizarre-galaxy-hurtling-towards-milky-way-1442009)

Quote
NASA and the European Space Agency (ESA) have released a spectacular image of Messier 90 in the constellation Virgo—a beautiful spiral galaxy located around 60 million light-years from our own Milky Way.

This galaxy is particularly interesting to astronomers because it is one of the few that have been observed traveling towards the Milky Way, not away from it.
Scientists know this because the light shining from the galaxy is "blueshifted."

Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 06/05/2019 12:34 am
Astronomy group calls for urgent action on SpaceX Starlink satellites (https://www.newscientist.com/article/2205172-astronomy-group-calls-for-urgent-action-on-spacex-starlink-satellites/)
Quote
We are entering the age of satellite constellations, and astronomers are worried. On 23 May, SpaceX launched 60 communications satellites, the first in a planned fleet of 12,000.

In the following days, the Starlink satellites moved in a bright line through the sky. Many astronomers on social media expressed concerns about how these shining projectiles would affect observations of the night sky, hurtling through images of the stars and creating streaks that are difficult or impossible to remove.

Now things have stepped up a notch. The International Astronomical Union, a key ruling body when it comes to the night sky, has released a statement echoing those concerns and calling for regulation of these sorts of satellite constellations.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2019 06:52 am
Heart of Lonesome Galaxy Is Brimming with Dark Matter (https://www.nasa.gov/mission_pages/chandra/images/heart-of-lonesome-galaxy-is-brimming-with-dark-matter.html)

Quote
Isolated for billions of years, a galaxy with more dark matter packed into its core than expected has been identified by astronomers using data from NASA’s Chandra X-ray Observatory.

The galaxy, known as Markarian 1216 (abbreviated as Mrk 1216), contains stars that are within 10% the age of the universe – that is, almost as old as the universe itself. Scientists have found that it has gone through a different evolution than typical galaxies, both in terms of its stars and the invisible dark matter that, through gravity, holds the galaxy together. Dark matter accounts for about 85% of the matter in the universe, although it has only been detected indirectly.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2019 06:53 am
Astronomy group calls for urgent action on SpaceX Starlink satellites (https://www.newscientist.com/article/2205172-astronomy-group-calls-for-urgent-action-on-spacex-starlink-satellites/)
Quote
We are entering the age of satellite constellations, and astronomers are worried. On 23 May, SpaceX launched 60 communications satellites, the first in a planned fleet of 12,000.

In the following days, the Starlink satellites moved in a bright line through the sky. Many astronomers on social media expressed concerns about how these shining projectiles would affect observations of the night sky, hurtling through images of the stars and creating streaks that are difficult or impossible to remove.

Now things have stepped up a notch. The International Astronomical Union, a key ruling body when it comes to the night sky, has released a statement echoing those concerns and calling for regulation of these sorts of satellite constellations.

I posted the related IAU press release in the Starlink discussion thread yesterday, UK time.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/06/2019 06:53 am
Quote
An asteroid up to double the width of the bolide that exploded in the atmosphere over Russia in 2013 is making a close approach of our planet this September, and there's a teeny tiny chance it could make an even bigger impact.

But it almost certainly won't. Asteroid 2006 QV89 currently has a one in 7,000 chance of hitting Earth on the morning of Sept. 9, according to the European Space Agency, which lists the space rock as the fourth most concerning object on its top 10 list of cosmic items with a non-zero chance of hitting us.

Current modeling of the asteroid's orbit shows it more likely passing by Earth at a distance of over 4.2 million miles (6.8 million km) this September, but ESA says there's a roughly one hundredth of 1% chance the model is way off and it hits our planet instead.

https://www.cnet.com/news/an-asteroid-has-a-very-tiny-chance-of-hitting-earth-this-year/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/06/2019 08:27 am
Bardeen–Petterson alignment, jets, and magnetic truncation in GRMHD simulations of tilted thin accretion discs (https://academic.oup.com/mnras/article/487/1/550/5420428)

ABSTRACT
Prevalent around luminous accreting black holes, thin discs are challenging to resolve in numerical simulations. When the disc and black hole angular momentum vectors are misaligned, the challenge becomes extreme, requiring adaptive meshes to follow the disc proper as it moves through the computational grid. With our new high-performance general relativistic magnetohydrodynamic (GRMHD) code H-AMR, we have simulated the thinnest accretion disc to date, of aspect ratio H/R ≈ 0.03 ≈ 1.7°, around a rapidly spinning (a ≈ 0.9) black hole, using a cooling function. Initially tilted at 10°, the disc warps inside ∼5 rg into alignment with the black hole, where rg is the gravitational radius. This is the first demonstration of Bardeen–Petterson alignment in MHD with viscosity self-consistently generated by magnetized turbulence. The disc develops a low-density high-viscosity (αeff ∼ 1.0) magnetic-pressure–dominated inner region at r  25rg that rapidly empties itself into the black hole. This inner region may, in reality, due to thermal decoupling of ions and electrons, evaporate into a radiatively inefficient accretion flow if, as we propose, the cooling time exceeds the accretion time set by the order unity effective viscosity. We furthermore find the unexpected result that even our very thin disc can sustain large-scale vertical magnetic flux on the black hole, which launches powerful relativistic jets that carry 20−50 per cent
 of the accretion power along the angular momentum vector of the outer tilted disc, providing a potential explanation for the origin of jets in radio-loud quasars.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/06/2019 09:18 am
eso1910 — Organisation Release
ESO contributes to protecting Earth from dangerous asteroids (https://www.eso.org/public/news/eso1910/)

The unique capabilities of the SPHERE instrument on ESO’s Very Large Telescope have enabled it to obtain the sharpest images of a double asteroid as it flew by Earth on 25 May. While this double asteroid was not itself a threatening object, scientists used the opportunity to rehearse the response to a hazardous Near-Earth Object (NEO), proving that ESO’s front-line technology could be critical in planetary defence.

The International Asteroid Warning Network (IAWN) coordinated a cross-organisational observing campaign of the asteroid 1999 KW4 as it flew by Earth, reaching a minimum distance of 5.2 million km [1] on 25 May 2019. 1999 KW4 is about 1.3 km wide, and does not pose any risk to Earth. Since its orbit is well known, scientists were able to predict this fly-by and prepare the observing campaign.

ESO joined the campaign with its flagship facility, the Very Large Telescope (VLT). The VLT is equipped with SPHERE — one of the very few instruments in the world capable of obtaining images sharp enough to distinguish the two components of the asteroid, which are separated by around 2.6 km.

SPHERE was designed to observe exoplanets; its state-of-the-art adaptive optics (AO) system corrects for the turbulence of the atmosphere, delivering images as sharp as if the telescope were in space. It is also equipped with coronagraphs to dim the glare of bright stars, exposing faint orbiting exoplanets.

Taking a break from its usual night job hunting exoplanets, SPHERE data helped astronomers characterise the double asteroid. In particular, it is now possible to measure whether the smaller satellite has the same composition as the larger object. 

“These data, combined with all those that are obtained on other telescopes through the IAWN campaign, will be essential for evaluating effective deflection strategies in the event that an asteroid was found to be on a collision course with Earth,” explained ESO astronomer Olivier Hainaut. “In the worst possible case, this knowledge is also essential to predict how an asteroid could interact with the atmosphere and Earth’s surface, allowing us to mitigate damage in the event of a collision.”

“The double asteroid was hurtling by the Earth at more than 70 000 km/h, making observing it with the VLT challenging,” said Diego Parraguez, who was piloting the telescope. He had to use all his expertise to lock on to the fast asteroid and capture it with SPHERE.

Bin Yang, VLT astronomer, declared “When we saw the satellite in the AO-corrected images, we were extremely thrilled. At that moment, we felt that all the pain, all the efforts were worth it.” Mathias Jones, another VLT astronomer involved in these observations, elaborated on the difficulties. “During the observations the atmospheric conditions were a bit unstable. In addition, the asteroid was relatively faint and moving very fast in the sky, making these observations particularly challenging, and causing the AO system to crash several times. It was great to see our hard work pay off despite the difficulties!”

While 1999 KW4 is not an impact threat, it bears a striking resemblance to another binary asteroid system called Didymos which could pose a threat to Earth sometime in the distant future.

Didymos and its companion called “Didymoon” are the target of a future pioneering planetary defence experiment. NASA’s DART spacecraft will impact Didymoon in an attempt to change its orbit around its larger twin, in a test of the feasibility of deflecting asteroids. After the impact, ESA’s Hera mission will survey the Didymos asteroids in 2026 to gather key information, including Didymoon’s mass, its surface properties and the shape of the DART crater.

The success of such missions depends on collaborations between organisations, and tracking Near-Earth Objects is a major focus for the collaboration between ESO and ESA. This cooperative effort has been ongoing since their first successful tracking of a potentially hazardous NEO in early 2014.

“We are delighted to be playing a role in keeping Earth safe from asteroids,” said Xavier Barcons, ESO’s Director General. “As well as employing the sophisticated capabilities of the VLT, we are working with ESA to create prototypes for a large network to take asteroid detection, tracking and characterization to the next level.”

This recent close encounter with 1999 KW4 comes just a month before Asteroid Day, an official United Nations day of education and awareness about asteroids, to be celebrated on 30 June. Events will be held on five continents, and ESO will be among the major astronomical organisations taking part. The ESO Supernova Planetarium &amp; Visitor Centre will host a range of activities on the theme of asteroids on the day, and members of the public are invited to join in the celebrations.

Notes
[1] This distance is about 14 times the distance to the Moon — close enough to study, but not close enough to be threatening! Many small asteroids fly past the Earth much closer than 1999 KW4, occasionally closer than the Moon. Earth’s most recent encounter with an asteroid took place on 15 February 2013, when a previously unknown asteroid 18 metres across exploded as it entered Earth's atmosphere over the Russian city of Chelyabinsk. The damage produced by the subsequent shockwave caused injuries to about 1,500 people.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/07/2019 06:47 am
A cool accretion disk around the Galactic Centre black hole (https://www.nature.com/articles/s41586-019-1242-z)

There is a supermassive black hole of mass 4 × 106 solar masses at the centre of the Milky Way1,2. A large reservoir of hot (107 kelvin) and cooler (102 to 104 kelvin) gas surrounds it within a few parsecs3. Although constraints on the amount of hot gas in the accretion zone of the black hole—that is, within 105 Schwarzschild radii (0.04 parsecs)—have been provided by X-ray observations4,5,6, the mass in cooler gas has been unconstrained. One possible way this cooler gas could be detected is by its emission in hydrogen recombination spectral lines7,8. Here we report imaging of a 104-kelvin ionized gas disk within 2 × 104 Schwarzschild radii, using the 1.3-millimetre recombination line H30α. This emission line is double-peaked, with full velocity linewidth of about 2,200 kilometres per second. The emission is centred on the radio source Sagittarius A*, but the redshifted side is displaced 0.11 arcsec (0.004 parsecs at a distance of 8 kiloparsecs) to the northeast and the blueshifted side is displaced a similar distance to the southwest. We interpret these observations in terms of a rotating disk of mass 10−5 to 10−4 solar masses and mean hydrogen density of about 105 to 106 per cubic centimetre, with the values being sensitive to the assumed geometry. The emission is stronger than expected, given the upper limit on the strength of the Brγ spectral line of hydrogen. We suggest that the H30α transition is enhanced by maser emission.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/10/2019 06:36 pm
Cool, nebulous ring around Milky Way's supermassive black hole (https://www.eurekalert.org/pub_releases/2019-06/nrao-cnr060519.php)

New ALMA observations reveal a never-before-seen disk of cool, interstellar gas wrapped around the supermassive black hole at the center of the Milky Way. This nebulous disk gives astronomers new insights into the workings of accretion: the siphoning of material onto the surface of a black hole. The results are published in the journal Nature.

Through decades of study, astronomers have developed a clearer picture of the chaotic and crowded neighborhood surrounding the supermassive black hole at the center of the Milky Way. Our galactic center is approximately 26,000 light-years from Earth and the supermassive black hole there, known as Sagittarius A* (A "star"), is 4 million times the mass of our Sun.

We now know that this region is brimming with roving stars, interstellar dust clouds, and a large reservoir of both phenomenally hot and comparatively colder gases. These gases are expected to orbit the black hole in a vast accretion disk that extends a few tenths of a light-year from the black hole's event horizon.

Until now, however, astronomers have been able to image only the tenuous, hot portion of this flow of accreting gas, which forms a roughly spherical flow and showed no obvious rotation. Its temperature is estimated to be a blistering 10 million degrees Celsius (18 million degrees Fahrenheit), or about two-thirds the temperature found at the core of our Sun. At this temperature, the gas glows fiercely in X-ray light, allowing it to be studied by space-based X-ray telescopes, down to scale of about a tenth of a light-year from the black hole.

In addition to this hot, glowing gas, previous observations with millimeter-wavelength telescopes have detected a vast store of comparatively cooler hydrogen gas (about 10 thousand degrees Celsius, or 18,000 degrees Fahrenheit) within a few light-years of the black hole. The contribution of this cooler gas to the accretion flow onto the black hole was previously unknown.

Although our galactic center black hole is relatively quiet, the radiation around it is strong enough to cause hydrogen atoms to continually lose and recombine with their electrons. This recombination produces a distinctive millimeter-wavelength signal, which is capable of reaching Earth with very little losses along the way.

With its remarkable sensitivity and powerful ability to see fine details, the Atacama Large Millimeter/submillimeter Array (ALMA) was able to detect this faint radio signal and produce the first-ever image of the cooler gas disk at only about a hundredth of a light-year away (or about 1000 times the distance from the Earth to the Sun) from the supermassive black hole. These observations enabled the astronomers both to map the location and trace the motion of this gas. The researchers estimate that the amount of hydrogen in this cool disk is about one tenth the mass of Jupiter, or one ten-thousandth of the mass of the Sun.

By mapping the shifts in wavelengths of this radio light due to the Doppler effect (light from objects moving toward the Earth is slightly shifted to the "bluer" portion of the spectrum while light from objects moving away is slightly shifted to the "redder" portion), the astronomers could clearly see that the gas is rotating around the black hole. This information will provide new insights into the ways that black holes devour matter and the complex interplay between a black hole and its galactic neighborhood.

"We were the first to image this elusive disk and study its rotation," said Elena Murchikova, a member in astrophysics at the Institute for Advanced Study in Princeton, New Jersey, and lead author on the paper. "We are also probing accretion onto the black hole. This is important because this is our closest supermassive black hole. Even so, we still have no good understanding of how its accretion works. We hope these new ALMA observations will help the black hole give up some of its secrets."
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/11/2019 07:43 am
 eso1911 — Organisation Release
Breakthrough Watch and the European Southern Observatory achieve “first light” on upgraded planet-finding instrument to search for Earth-like planets in nearest star system (https://www.eso.org/public/news/eso1911/)

Newly-built planet-finding instrument installed on Very Large Telescope, Chile, begins 100-hour observation of nearby stars Alpha Centauri A and B, aiming to be first to directly image a habitable exoplanet

Breakthrough Watch, the global astronomical program looking for Earth-like planets around nearby stars, and the European Southern Observatory (ESO), Europe’s foremost intergovernmental astronomical organisation, today announced “first light” on a newly-built planet-finding instrument at ESO’s Very Large Telescope in the Atacama Desert, Chile.

The instrument, called NEAR (Near Earths in the AlphaCen Region), is designed to hunt for exoplanets in our neighbouring star system, Alpha Centauri, within the “habitable zones” of its two Sun-like stars, where water could potentially exist in liquid form. It has been developed over the last three years and was built in collaboration with the University of Uppsala in Sweden, the University of Liège in Belgium, the California Institute of Technology in the US, and Kampf Telescope Optics in Munich, Germany.

Since 23 May ESO’s astronomers at ESO’s Very Large Telescope (VLT) have been conducting  a ten-day observing run to establish the presence or absence of one or more planets in the star system. Observations will conclude tomorrow, 11 June. Planets in the system (twice the size of Earth or bigger), would be detectable with the upgraded instrumentation. The near- to thermal-infrared range is significant as it corresponds to the heat emitted by a candidate planet, and so enables astronomers to determine whether the planet’s temperature allows liquid water.

Alpha Centauri is the closest star system to our Solar System, at 4.37 light-years (about 25 trillion miles) away. It consists of two Sun-like stars, Alpha Centauri A and B, plus the red dwarf star, Proxima Centauri. Current knowledge of Alpha Centauri’s planetary systems is sparse. In 2016, a team using ESO instruments discovered one Earth-like planet orbiting Proxima Centauri. But Alpha Centauri A and B remain unknown quantities; it is not clear how stable such binary star systems are for Earth-like planets, and the most promising way to establish whether they exist around these nearby stars is to attempt to observe them.

Imaging such planets, however, is a major technical challenge, since the starlight that reflects off them is generally billions of times dimmer than the light coming to us directly from their host stars; resolving a small planet close to its star at a distance of several light-years has been compared to spotting a moth circling a street lamp dozens of miles away. To solve this problem, in 2016 Breakthrough Watch and ESO launched a collaboration to build a special instrument called a thermal infrared coronagraph, designed to block out most of the light coming from the star and optimised to capture the infrared light emitted by the warm surface of an orbiting planet, rather than the small amount of starlight it reflects. Just as objects near to the Sun (normally hidden by its glare) can be seen during a total eclipse, so the coronagraph creates a kind of artificial eclipse of its target star, blocking its light and allowing much dimmer objects in its vicinity to be detected. This marks a significant advance in observational capabilities.

The coronagraph has been installed on one of the VLT’s four 8-metre-aperture telescopes, upgrading and modifying an existing instrument, called VISIR, to optimise its sensitivity to infrared wavelengths associated with potentially habitable exoplanets. It will therefore be able to search for heat signatures similar to that of the Earth, which absorbs energy from the Sun and emits it in the thermal infrared wavelength range. NEAR modifies the existing VISIR instrument in three ways, combining several cutting-edge astronomical engineering achievements. First, it adapts the instrument for coronagraphy, enabling it to drastically reduce the light of the target star and thereby reveal the signatures of potential terrestrial planets. Second, it uses a technique called adaptive optics to strategically deform the telescope’s secondary mirror, compensating for the blur produced by the Earth’s atmosphere. Third, it employs novel chopping strategies that also reduce noise, as well as potentially allowing the instrument to switch rapidly between target stars -— as fast as every 100 milliseconds — maximising the available telescope time.

Pete Worden, Executive Director of the Breakthrough Initiatives, said: “We’re delighted to collaborate with the ESO in designing, building, installing and now using this innovative new instrument. If there are Earth-like planets around Alpha Centauri A and B, that’s huge news for everyone on our planet.”

“ESO is glad to bring its expertise, existing infrastructure, and observing time on the Very Large Telescope to the NEAR project,” commented ESO project manager Robin Arsenault.

“This is a valuable opportunity, as — in addition to its own science goals — the NEAR experiment is also a pathfinder for future planet-hunting instruments for the upcoming Extremely Large Telescope,” says Markus Kasper, ESO’s lead scientist for NEAR.

“NEAR is the first and (currently) only project that could directly image a habitable exoplanet. It marks an important milestone. Fingers crossed — we are hoping a large habitable planet is orbiting Alpha Cen A or B” commented Olivier Guyon, lead scientist for Breakthrough Watch.

“Human beings are natural explorers,” said Yuri Milner, founder of the Breakthrough Initiatives, “It is time we found out what lies beyond the next valley. This telescope will let us gaze across.”
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/11/2019 09:57 am
Mass anomaly detected under the moon's largest crater (https://m.phys.org/news/2019-06-mass-anomaly-moon-largest-crater.html)

Quote
A mysterious large mass of material has been discovered beneath the largest crater in our solar system—the Moon's South Pole-Aitken basin—and may contain metal from the asteroid that crashed into the Moon and formed the crater, according to a Baylor University study.

"Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That's roughly how much unexpected mass we detected," said lead author Peter B. James,
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 06/11/2019 02:40 pm
eso1911 — Organisation Release
Breakthrough Watch and the European Southern Observatory achieve “first light” on upgraded planet-finding instrument to search for Earth-like planets in nearest star system (https://www.eso.org/public/news/eso1911/)

Newly-built planet-finding instrument installed on Very Large Telescope, Chile, begins 100-hour observation of nearby stars Alpha Centauri A and B, aiming to be first to directly image a habitable exoplanet


I'm especially excited about this one!  It is supposed to be wrapping up that 100-hours as of today (June 11).  Thus far it is known there aren't any giant planets around A,B, or Proxima, but there's still the possibility of subjovians or terrestials.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/11/2019 04:54 pm
eso1911 — Organisation Release
Breakthrough Watch and the European Southern Observatory achieve “first light” on upgraded planet-finding instrument to search for Earth-like planets in nearest star system (https://www.eso.org/public/news/eso1911/)

Newly-built planet-finding instrument installed on Very Large Telescope, Chile, begins 100-hour observation of nearby stars Alpha Centauri A and B, aiming to be first to directly image a habitable exoplanet


I'm especially excited about this one!  It is supposed to be wrapping up that 100-hours as of today (June 11).  Thus far it is known there aren't any giant planets around A,B, or Proxima, but there's still the possibility of subjovians or terrestials.

Reading that press release it doesn’t appear to be able to get down to super-Earth sized planets.
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 06/12/2019 12:58 am
Reading that press release it doesn’t appear to be able to get down to super-Earth sized planets.

References from newer releases, like from Space.com, stated that planets twice the size of Earth (perhaps in diameter) were the lower end of the search.  This still seems closer to superearth status than subjovian (or miniNepture).  The search period ran from May 21 to today (June 11); I suspect results won't be know until the data sifted over the next few months (not that a news results would be unwelcome).
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/12/2019 08:31 am
Reading that press release it doesn’t appear to be able to get down to super-Earth sized planets.

References from newer releases, like from Space.com, stated that planets twice the size of Earth (perhaps in diameter) were the lower end of the search.  This still seems closer to superearth status than subjovian (or miniNepture).  The search period ran from May 21 to today (June 11); I suspect results won't be know until the data sifted over the next few months (not that a news results would be unwelcome).

Thanks. I was curious because as you point out other sources seemed at variance with the press release on the matter.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 06/12/2019 12:50 pm
Reading that press release it doesn’t appear to be able to get down to super-Earth sized planets.

References from newer releases, like from Space.com, stated that planets twice the size of Earth (perhaps in diameter) were the lower end of the search.  This still seems closer to superearth status than subjovian (or miniNepture).  The search period ran from May 21 to today (June 11); I suspect results won't be know until the data sifted over the next few months (not that a news results would be unwelcome).

The limit is down to 1.9 Earth radii assuming an Earth-like atmosphere, though realistically such a thing may not physically exist to be able to find. Assuming a 1.9 radii the Fulton gap suggests such a planet would be a mini-Neptune rather than have Earth-like emission.

On the other hand NEAR might get down to a 1.3 Earth radii ~50 Celsius low-albedo desert planet (or one slightly larger and cooler), which I would expect to be far more likely to exist than a super-large Earth.

So it can’t find a super-Earth but it possibly could find a warm super-Mercury, theoretically at least.

See;

https://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf

http://www.iac.es/congreso/AO4ELT5/media/proceedings/proceeding-044.pdf

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/12/2019 01:45 pm
BATTLE OF THE BULGES: HAVE ASTRONOMERS BEEN WRONG ABOUT SPIRAL GALAXIES ALL THIS TIME? (https://www.syfy.com/syfywire/battle-of-the-bulges-have-astronomers-been-wrong-about-spiral-galaxies-all-this-time)

Quote
Some big news from Galaxy Zoo: It's looking very much like a classic classification scheme for galaxies — first dreamed up by Edwin Hubble himself! — may be, um,  wrong. The consequences of this are as dramatic as they are cosmic: It implies very strongly that the way we've been thinking about how galaxies form and maintain spiral arms is also wrong. Instead of being semi-permanent features of galaxies, they may instead actually wind themselves up, disappear, and reform again!
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 06/12/2019 02:47 pm
Reading that press release it doesn’t appear to be able to get down to super-Earth sized planets.

References from newer releases, like from Space.com, stated that planets twice the size of Earth (perhaps in diameter) were the lower end of the search.  This still seems closer to superearth status than subjovian (or miniNepture).  The search period ran from May 21 to today (June 11); I suspect results won't be know until the data sifted over the next few months (not that a news results would be unwelcome).

The limit is down to 1.9 Earth radii assuming an Earth-like atmosphere, though realistically such a thing may not physically exist to be able to find. Assuming a 1.9 radii the Fulton gap suggests such a planet would be a mini-Neptune rather than have Earth-like emission.

On the other hand NEAR might get down to a 1.3 Earth radii ~50 Celsius low-albedo desert planet (or one slightly larger and cooler), which I would expect to be far more likely to exist than a super-large Earth.

So it can’t find a super-Earth but it possibly could find a warm super-Mercury, theoretically at least.

See;

https://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf

http://www.iac.es/congreso/AO4ELT5/media/proceedings/proceeding-044.pdf

As far as analyzing Alpha Centauri as a system, it'll quickly verify if jovian or subjovian planets orbit either A or B, much as before the discovery of Proxima b it was it was verified that Proxima lacked those planets within ~2 AU of the star.  Getting back to A & B, because they are in the middle range of binary orbits (neither extremely close or extremely distant [the later just look to Proxima for]) finding out where any large planets are present would validate any theories on how binaries form.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/13/2019 05:50 am
Sodium chloride on the surface of Europa (https://advances.sciencemag.org/content/5/6/eaaw7123)

The potential habitability of Europa’s subsurface ocean depends on its chemical composition, which may be reflected in that of Europa’s geologically young surface. Investigations using Galileo Near-Infrared Mapping Spectrometer data led to the prevailing view that Europa’s endogenous units are rich in sulfate salts. However, recent ground-based infrared observations have suggested that, while regions experiencing sulfur radiolysis may contain sulfate salts, Europa’s more pristine endogenous material may reflect a chloride-dominated composition. Chlorides have no identifying spectral features at infrared wavelengths, but develop distinct visible-wavelength absorptions under irradiation, like that experienced on the surface of Europa. Using spectra obtained with the Hubble Space Telescope, we present the detection of a 450-nm absorption indicative of irradiated sodium chloride on the surface. The feature correlates with geologically disrupted chaos terrain, suggesting an interior source. The presence of endogenous sodium chloride on the surface of Europa has important implications for our understanding of its subsurface chemistry.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/13/2019 08:17 pm
New evidence shows crash with Antlia 2 gave the Milky Way the ripples in its outer disc (https://www.rit.edu/news/new-evidence-shows-crash-antlia-2-gave-milky-way-ripples-its-outer-disc)

Quote
The newly-discovered dark dwarf galaxy Antlia 2’s collision with the Milky Way may be responsible for our galaxy’s characteristic ripples in its outer disc, according to a study led by Rochester Institute of Technology Assistant Professor Sukanya Chakrabarti.

Jupiter-like exoplanets found in sweet spot in most planetary systems (https://news.berkeley.edu/2019/06/12/jupiter-like-exoplanets-found-in-sweet-spot-in-most-planetary-systems/)

Quote
As planets form in the swirling gas and dust around young stars, there seems to be a sweet spot where most of the large, Jupiter-like gas giants congregate, centered around the orbit where Jupiter sits today in our own solar system.

The location of this sweet spot is between 3 and 10 times the distance Earth sits from our sun (3-10 astronomical units, or AU). Jupiter is 5.2 AU from our sun.

That’s just one of the conclusions of an unprecedented analysis of 300 stars captured by the Gemini Planet Imager, or GPI, a sensitive infrared detector mounted on the 8-meter Gemini South telescope in Chile.

HUBBLE OBSERVES TINY GALAXY WITH BIG HEART [HEIC1911] (http://sci.esa.int/hubble/61410-hubble-observes-tiny-galaxy-with-big-heart-heic1911/)

Quote
Nestled within this field of bright foreground stars lies ESO 495-21, a tiny galaxy with a big heart. ESO 495-21 may be just 3000 light-years across, but that is not stopping the galaxy from furiously forming huge numbers of stars. It may also host a supermassive black hole; this is unusual for a galaxy of its size, and may provide intriguing hints as to how galaxies form and evolve.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/17/2019 08:46 pm
Meteors help Martian clouds form (https://www.colorado.edu/today/2019/06/17/meteors-help-martian-clouds-form)

Quote
How did the Red Planet get all of its clouds? CU Boulder researchers may have discovered the secret: just add meteors.

Astronomers have long observed clouds in Mars’ middle atmosphere, which begins about 18 miles (30 kilometers) above the surface, but have struggled to explain how they formed.

Key takeaways
Scientists have observed clouds in Mars' middle atmosphere, beginning about 18 miles above the planet's surface, but can't explain how they form.
A new study suggests that these clouds get help from "meteoric smoke"—or the dust created by space debris breaking apart in Mars' atmosphere.
These clouds can have large impacts on the climate of Mars, researchers report.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/18/2019 02:04 pm
It’s an ancient and eerily quiet red dwarf star, unlike some of the others of its kind that planets have been found around. It is also much closer to us than something like the TRAPPIST system. Only slight issue is they don’t know its rotation speed.

Two potentially life-friendly planets found orbiting a nearby star (https://www.nationalgeographic.com/science/2019/06/two-potentially-life-friendly-planets-found-12-light-years-away-teegardens-star/)

Quote
A tiny, old star just 12 light-years away might host two temperate, rocky planets, astronomers announced today. If they’re confirmed, both of the newly spotted worlds are nearly identical to Earth in mass, and both planets are in orbits that could allow liquid water to trickle and puddle on their surfaces.

Scientists estimate that the stellar host, known as Teegarden’s star, is at least eight billion years old, or nearly twice the sun’s age. That means any planets orbiting it are presumably as ancient, so life as we know it has had more than enough time to evolve. And for now, the star is remarkably quiet, with few indications of the tumultuous stellar quakes and flares that tend to erupt from such objects.
Title: Re: Astronomy & Planetary Science Thread
Post by: RonM on 06/18/2019 06:27 pm
It’s an ancient and eerily quiet red dwarf star, unlike some of the others of its kind that planets have been found around. It is also much closer to us than something like the TRAPPIST system. Only slight issue is they don’t know its rotation speed.

Two potentially life-friendly planets found orbiting a nearby star (https://www.nationalgeographic.com/science/2019/06/two-potentially-life-friendly-planets-found-12-light-years-away-teegardens-star/)

Quote
A tiny, old star just 12 light-years away might host two temperate, rocky planets, astronomers announced today. If they’re confirmed, both of the newly spotted worlds are nearly identical to Earth in mass, and both planets are in orbits that could allow liquid water to trickle and puddle on their surfaces.

Scientists estimate that the stellar host, known as Teegarden’s star, is at least eight billion years old, or nearly twice the sun’s age. That means any planets orbiting it are presumably as ancient, so life as we know it has had more than enough time to evolve. And for now, the star is remarkably quiet, with few indications of the tumultuous stellar quakes and flares that tend to erupt from such objects.

When Teegarden's star was young it would have had massive flares like other young red dwarf stars. The question is whether or not the planets would have retained enough of their atmospheres for liquid water. Fortunately, Teegarden's star is close, so we'll get answers not long after observations become possible.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/19/2019 06:30 am
Scientists read the Sun’s History in Moon Rocks (http://blogs.discovermagazine.com/d-brief/2019/06/18/scientists-read-the-suns-history-in-moon-rocks/)

Quote
Stars, like humans, are more volatile when they’re young. As sunlike stars mature past their first billion years, they all tend to slow in their rotation, eventually converging to roughly the same period we see now in our sun: about 27 days for a star the same mass as our sun.

But when stars are young, they rotate more quickly and less predictably. Two stars of the same size may rotate at drastically different speeds. And stars that are fast rotators tend to shoot out more solar flares and coronal mass ejections, hurling powerful radiation and charged particles into their systems, often to the detriment of the planets around them.

Researchers from NASA’s Goddard Space Flight Center, led by Prabal Saxena, published a study May 3 in the Astrophysical Journal Letters, where they used the moon’s surface to measure just how active our sun was in its early years, a factor that strongly determined how the inner planets, including Earth, evolved.[/url]
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 06/19/2019 03:08 pm
It’s an ancient and eerily quiet red dwarf star, unlike some of the others of its kind that planets have been found around. It is also much closer to us than something like the TRAPPIST system. Only slight issue is they don’t know its rotation speed.

Two potentially life-friendly planets found orbiting a nearby star (https://www.nationalgeographic.com/science/2019/06/two-potentially-life-friendly-planets-found-12-light-years-away-teegardens-star/)

Quote
A tiny, old star just 12 light-years away might host two temperate, rocky planets, astronomers announced today. If they’re confirmed, both of the newly spotted worlds are nearly identical to Earth in mass, and both planets are in orbits that could allow liquid water to trickle and puddle on their surfaces.

Scientists estimate that the stellar host, known as Teegarden’s star, is at least eight billion years old, or nearly twice the sun’s age. That means any planets orbiting it are presumably as ancient, so life as we know it has had more than enough time to evolve. And for now, the star is remarkably quiet, with few indications of the tumultuous stellar quakes and flares that tend to erupt from such objects.

When Teegarden's star was young it would have had massive flares like other young red dwarf stars. The question is whether or not the planets would have retained enough of their atmospheres for liquid water. Fortunately, Teegarden's star is close, so we'll get answers not long after observations become possible.

Here's the paper:
The CARMENES search for exoplanets around M dwarfs
Two temperate Earth-mass planet candidates around Teegarden’s Star? (https://www.aanda.org/articles/aa/pdf/forth/aa35460-19.pdf)

Unfortunately, these planets were discovered by the radial-velocity method; they don't transit, thereby ruling out the common method of exoplanet atmospheric characterisation.

The system is 8 billion years old. The planets may have reconstituted their atmospheres from volcanism and impacts. Though that would be affected by whether they have retained a sufficiently strong magnetic field.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/21/2019 10:35 am
Astronomers see “warm” glow of Uranus’s rings (https://news.berkeley.edu/2019/06/20/astronomers-see-warm-glow-of-uranuss-rings/)

Quote
The rings of Uranus are invisible to all but the largest telescopes — they weren’t even discovered until 1977 — but they’re surprisingly bright in new heat images of the planet taken by two large telescopes in the high deserts of Chile.

The thermal glow gives astronomers another window onto the rings, which have been seen only because they reflect a little light in the visible, or optical, range and in the near-infrared. The new images taken by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope (VLT) allowed the team for the first time to measure the temperature of the rings: a cool 77 Kelvin, or 77 degrees above absolute zero — the boiling temperature of liquid nitrogen and equivalent to 320 degrees below zero Fahrenheit.

Abundance of gases in Enceladus’s ocean are a potential fuel — if life is there to consume it (https://www.washington.edu/news/2019/06/19/abundance-of-gases-in-enceladuss-ocean-are-a-potential-fuel-if-life-is-there-to-consume-it/)

Quote
The subsurface ocean of Saturn’s moon Enceladus probably has higher than previously known concentrations of carbon dioxide and hydrogen and a more Earthlike pH level, possibly providing conditions favorable to life, according to new research from planetary scientists at the University of Washington.

The presence of such high concentrations could provide fuel — a sort of chemical “free lunch” — for living microbes, said lead researcher Lucas Fifer a UW doctoral student in Earth and space sciences. Or, it could mean “that there is hardly anyone around to eat it.”
Title: Re: Astronomy & Planetary Science Thread
Post by: Eric Hedman on 06/22/2019 04:40 am
The final approval for building the Thirty Meter Telescope on Mauna Kea has been done:

https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1 (https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1)

It will be interesting to see how this compare to Hubble images.  I will be anxiously awaiting first light.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2019 07:19 am
The final approval for building the Thirty Meter Telescope on Mauna Kea has been done:

https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1 (https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1)

It will be interesting to see how this compare to Hubble images.  I will be anxiously awaiting first light.

I can’t see this project as not being free of controversy going forward being as it seems some native Hawaiians are still upset about it.
Title: Re: Astronomy & Planetary Science Thread
Post by: Eric Hedman on 06/22/2019 03:09 pm
The final approval for building the Thirty Meter Telescope on Mauna Kea has been done:

https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1 (https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1)

It will be interesting to see how this compare to Hubble images.  I will be anxiously awaiting first light.

I can’t see this project as not being free of controversy going forward being as it seems some native Hawaiians are still upset about it.
Everything seems to cause some controversy these days.  There may be complaints and protests as construction advances, but I don't think it will stop the telescope.  It is one of only a handful of spots where a telescope like this can be built.  One thing that is painfully obvious reading the forums here or on any website, you can never get a complete consensus on anything.  If you wait for that, nothing would ever be accomplished.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2019 06:20 pm
The final approval for building the Thirty Meter Telescope on Mauna Kea has been done:

https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1 (https://apnews.com/ed9b871b97314a0e832fb4116a8d22b1)

It will be interesting to see how this compare to Hubble images.  I will be anxiously awaiting first light.

I can’t see this project as not being free of controversy going forward being as it seems some native Hawaiians are still upset about it.
Everything seems to cause some controversy these days.  There may be complaints and protests as construction advances, but I don't think it will stop the telescope.  It is one of only a handful of spots where a telescope like this can be built.  One thing that is painfully obvious reading the forums here or on any website, you can never get a complete consensus on anything.  If you wait for that, nothing would ever be accomplished.

True and it’s not like astronomers haven’t listened and taken onboard the native Hawaiian culture. Both the first interstellar object and first photographed black hole have been given Hawaiian names.
Title: Re: Astronomy & Planetary Science Thread
Post by: jgoldader on 06/22/2019 07:38 pm
Having observed there many times, I always felt the summit of Mauna Kea was a special place--like going into a church.  It's an unfortunate situation for all involved.
Title: Re: Astronomy & Planetary Science Thread
Post by: theinternetftw on 06/22/2019 11:55 pm
True and it’s not like astronomers haven’t listened and taken onboard the native Hawaiian culture. Both the first interstellar object and first photographed black hole have been given Hawaiian names.

If someone sets up shop on a landmark vitally important to your heritage without your permission to build something important to them but not to you, then starts delving through your culture to slap names on what they find (which you already didn't care about), I can assure you that the result will not be a bunch of folks thankful to have their culture being taken onboard.

What they care about is the mountain, so I'd talk about that.  I hope someone is making sure anyone concerned knows about the fact that there is a plan to painstakingly remove each telescope once no longer in use (http://www.malamamaunakea.org/management/comprehensive-management-plan/decommissioning), involving not only deconstruction of the telescope but restoring the site to a natural state.  This isn't an empty promise: in order to add TMT to the mountain, it was agreed that three older telescopes will be removed as soon as possible, with two more being removed by 2033. (https://youtube.com/watch?v=PKiLbCdASQ8)

There's a lot of interesting information in the plan those decommissioning rules come from (http://www.malamamaunakea.org/uploads/management/plans/CMP_2009.PDF).  Section 1 does a very good job of explaining the context of Mauna Kea for Hawaiians, and just what it means for the telescopes to be exactly where they are on that mountain, all in about three and a half pages.  If all anyone has read before is news articles about this, that might be a good thing to check out.

Reading that document, there's clearly a lot of time, effort, and care being spent on trying to get this right by folks who respect what this site means to native Hawaiians (many of which are probably native Hawaiians themselves).
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/23/2019 07:03 am
True and it’s not like astronomers haven’t listened and taken onboard the native Hawaiian culture. Both the first interstellar object and first photographed black hole have been given Hawaiian names.

If someone sets up shop on a landmark vitally important to your heritage without your permission to build something important to them but not to you, then starts delving through your culture to slap names on what they find (which you already didn't care about), I can assure you that the result will not be a bunch of folks thankful to have their culture being taken onboard.

What they care about is the mountain, so I'd talk about that.  I hope someone is making sure anyone concerned knows about the fact that there is a plan to painstakingly remove each telescope once no longer in use (http://www.malamamaunakea.org/management/comprehensive-management-plan/decommissioning), involving not only deconstruction of the telescope but restoring the site to a natural state.  This isn't an empty promise: in order to add TMT to the mountain, it was agreed that three older telescopes will be removed as soon as possible, with two more being removed by 2033. (https://youtube.com/watch?v=PKiLbCdASQ8)

There's a lot of interesting information in the plan those decommissioning rules come from (http://www.malamamaunakea.org/uploads/management/plans/CMP_2009.PDF).  Section 1 does a very good job of explaining the context of Mauna Kea for Hawaiians, and just what it means for the telescopes to be exactly where they are on that mountain, all in about three and a half pages.  If all anyone has read before is news articles about this, that might be a good thing to check out.

Reading that document, there's clearly a lot of time, effort, and care being spent on trying to get this right by folks who respect what this site means to native Hawaiians (many of which are probably native Hawaiians themselves).

I think my point poorly made was that there was native Hawaiians involved in the naming.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/25/2019 06:22 am
 The Crab Nebula just blasted Earth with the highest-energy photons ever recorded (https://www.technologyreview.com/s/613840/crab-nebula-photons-earth-astronomy-space-astrophysics/)

Quote
Until now. Today, researchers from the Tibet Air Shower Gamma Collaboration say they have observed photons with energies above 100 TeV for the first time, including a remarkable photon with an energy of almost 500 TeV. This single photon has about the same energy as a falling Ping-Pong ball and is the highest-energy photon ever recorded.

The collaboration has also worked out where these photons are coming from: the Crab Nebula, the remnants of a supernova that occurred in 1054 AD in the Perseus Arm of the Milky Way, some 6,500 light-years from Earth.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/25/2019 08:07 pm
How icy outer solar system satellites may have formed (https://www.sciencedaily.com/releases/2019/06/190625093312.htm)

Quote
Summary:
Beyond the orbit of the planet Neptune, there are a multitude of icy and rocky small bodies, smaller than planets but larger than comets. These likely formed at the same time as the Solar System, and understanding their origin could provide important clues as to how the entire Solar System originated. Using sophisticated computer simulations and observations of TNOs, astronomers have shown how these so-called trans-Neptunian Objects (or TNOs) may have formed.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/26/2019 01:21 pm
 Astronomers Have Decoded a Weird Signal Coming from a Strange, 3-Body Star System (https://www.livescience.com/65794-brown-dwarf-detected.html)

Quote
Once or twice a day, a strange object in the Milky Way blinks at us. Now, astronomers think they know why.

The object is called NGTS-7, and to most telescopes it looks like a single star. Researchers at the University of Warwick in England started watching because it seemed to be emitting flares, but on closer examination they noticed that its starlight dims briefly every 16.2 hours. When the astronomers zoomed in, they realized there are actually two similarly sized stars in the system, and that only one of them is dimming briefly in that way — suggesting that there's something dark circling on or just above the star's surface. Now, in a paper posted to the preprint journal arXiv, the astronomers offer an explanation: A brown dwarf is orbiting one of the stars, in an orbit so tight that it takes just 16.2 hours to complete.

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/27/2019 08:00 pm
Bizarre radio burst traced back to its origin in deep space (https://www.nationalgeographic.com/science/2019/06/mysterious-fast-radio-burst-traced-to-home-galaxy-deep-space/)

Quote
With 36 radio dishes spread over more than two square miles, astronomers could use slight delays in the burst’s arrival at different dishes to help pinpoint its location on the sky. And on September 24, 2018, while running special software designed to localize single bursts, that array caught its quarry, now known as FRB 180924.

Follow-up observations with optical telescopes in Hawaii and Chile helped the team identify the burst’s home as a galaxy roughly 3.6 billion light-years away. Specifically, the burst hails from the outskirts of large, possibly spiral galaxy that’s perhaps quite similar to a younger Milky Way.

“The host galaxy is actually rather boring,” Bannister says. “Most stars in the universe live in galaxies such as this. So, it’s not unusual if you’re a star, but it’s a big difference from the FRB 121102 host.”

The galaxy is roughly a thousand times more massive than the strange, smudgy dwarf that FRB 121102 comes from, and it’s forming stars at a much slower rate. This means newly dead stars such as magnetars shouldn’t easily exist there, because the big, ballooning stars that collapse into dense stellar corpses normally live in regions where stars form more quickly.

“It's puzzling that these galaxies are really so different, but I think it tells us that we still have a lot to learn about FRB hosts,” Petroff says. “In a way, it's a relief to me that this one wasn't in a dwarf galaxy like the host of [FRB 121102]—that would be too easy!”
Title: Astronomy & Planetary Science Thread
Post by: Star One on 07/02/2019 10:33 pm
Here is a very recent short documentary looking at the origins of Flat Earthism. Their poll results do offer some relief that perhaps people aren’t as gullible as you might fear. It is also refreshingly mostly pretty scathing about the whole nonsense.

https://www.youtube.com/watch?v=P4l9Y5OHqpk
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 07/03/2019 06:25 am
Pairwise Tidal Equilibrium States and the Architecture of Extrasolar Planetary Systems (https://arxiv.org/abs/1907.00915) (arXiv)

Quote
(Abstract)
Current observations indicate that the planet formation process often produces multiple planet systems with nearly circular orbits, regular spacing, a narrow range of inclination angles, and similar planetary masses of order mp∼10M⊕. Motivated by the observational sample, this paper determines the tidal equilibrium states for this class of extrasolar planetary systems. We start by considering two planet systems with fixed orbital spacing and variable mass ratios. The basic conjecture explored in this paper is that the planet formation process will act to distribute planetary masses in order to achieve a minimum energy state. The resulting minimum energy configuration --- subject to the constraint of constant angular momentum --- corresponds to circular orbits confined to a plane, with nearly equal planetary masses (as observed). We then generalize the treatment to include multiple planet systems, where each adjacent pair of planets attains its (local) tidal equilibrium state. The properties of observed planetary systems are close to those expected from this pairwise equilibrium configuration. In contrast, observed systems do not reside in a global minimum energy state. Both the equilibrium states of this paper and observed multi-planet systems, with planets of nearly equal mass on regularly spaced orbits, have an effective surface density of the form σ∝r−2, much steeper than most disk models.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/03/2019 08:42 am
ESOcast 204 Light:  La Silla Total Solar Eclipse Concludes

https://youtu.be/FQNfs4r1ecM
Title: Re: Astronomy & Planetary Science Thread
Post by: bkellysky on 07/03/2019 02:20 pm

But that's the thing, it's [which planet is closest to each planet in our solar system] a trivial result that for any given planet, any circularly-orbiting object arbitrarily close to its star (with the limit being the star around which the planet under consideration orbits) will be closest to it on average.
. . .
The farther the considered planet orbits, the clearer this effect gets - hence why Mercury is the closest planet, on average, to *any* of the Solar System's planets, and even to Pluto whose results gets a bit more complicated due to eccentricity and plane inclination issues.

Sorry for the delay in rectifying my comments on this, but I've updated my blog post to give you credit and link to your explanation, here.
https://bkellysky.wordpress.com/2019/03/18/which-planet-is-closest-to-earth-most-often/
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/03/2019 07:12 pm
Quote
Saturn's moon Enceladus is an exciting place to look for life because it has an ocean of liquid water under its icy surface. But we don't know how old its ocean is. Old enough for life to emerge? Young enough that there are still sources of energy for life left untapped? To find out, we have simulated on a computer possible scenarios for how long Enceladus and other moons of Saturn have been around. In the scenario that best matches the real moons, the ocean of Enceladus is about a billion years old. That's good news for life: it should have had enough time to arise and there should still be some energy to power it.

https://agu.confex.com/agu/abscicon19/meetingapp.cgi/Paper/479049

 Saturn's Icy Moon Enceladus Is Likely the 'Perfect Age' to Harbor Life (https://www.livescience.com/65855-enceladus-billion-year-old-ocean.html)

Quote
Neveau and his team estimated the ocean's age with a little bit of guesswork. They ran about 50 simulations, plugging in various parameters based on measurements Cassini took, such as the details of Saturns' moons' orbits, the radioactivity of the rocks on Enceladus, and their own guesses as to the age of the moon and how it formed.

The simulation that best-replicated the icy moon's current conditions estimated that the ocean was 1 billion years old. However, Neveu cautions that this age estimation was based on a single simulation. And though it matches a lot of the conditions seen on Enceladus, it doesn't match all of them.

"For example, if you took the present day, the ocean would be refrozen in that simulation which is not what we're seeing." So the age of the ocean, should be taken with a grain of salt, Neveu said.

Neveu and his team are now working to make their simulation run faster. The hope is that, with the faster run time, and slightly improved models, they can more precisely date Enceladus' oceans. "We want to know this before we go back to search for life," he said.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/04/2019 05:51 am
The Secret to Planet Formation Might Be Hiding in the ‘Fulton Gap’

https://youtu.be/W4brTtjdH5Y
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/04/2019 08:16 pm
Ancient Northland kauri tree reveals secrets of Earth's polar reversal (https://i.stuff.co.nz/science/113954687/ancient-northland-kauri-tree-reveals-secrets-of-earths-polar-reversal)

Quote
A team of international scientists believe they have found the answers to the mysteries of Earth's last polar reversal in the tree rings of an ancient kauri.

The 20 metre-long kauri log could map out what to expect during a geomagnetic reversal – a change in the planet's magnetic field – including its impact on climate change and solar radiation.

The kauri, measuring a massive 2.5m in diameter, is one of the oldest trees ever found.

Quote
Now, carbon dating has confirmed the ancient kauri was alive 41,000 to 42,500 years ago, making it one of the oldest trees ever found.

"This Ngwh kauri is unique in the world," University of Waikato associate professor Alan Hogg, the director of the Waikato Radiocarbon Dating laboratory, said.

During its 1500-year lifespan, the tree experienced one of the earth's geomagnetic excursions, meaning the north magnetic pole drifted down to the southern hemisphere and back up again.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/07/2019 02:31 pm
Probably just me but it seems funny to think of a working observatory as also being a world heritage site.

https://www.theguardian.com/culture/2019/jul/07/jodrell-bank-observatory-becomes-world-heritage-site
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/08/2019 12:38 pm
Report makes case for space-based asteroid tracking telescope (https://spacenews.com/report-makes-case-for-space-based-asteroid-tracking-telescope/)

Quote
A report last month has buoyed the efforts of scientists seeking a dedicated mission to search for near Earth objects, although NASA has yet to commit to funding that mission.

The June 19 report by a National Academies committee concluded that a space-based infrared telescope is the best way to meet a goal established by Congress more than a decade ago of identifying all the potentially hazardous near Earth objects (NEOs) at least 140 meters in diameter.

Quote
Advocates of NEOCam hope that the report can help build the case for funding the mission, likely outside of existing planetary science programs. NEOCam was one of five finalists in the latest competition for Discovery class missions. NASA ultimately selected in January 2017 two other asteroid missions, Lucy and Psyche, but did provide “extended Phase A” funding to continue work on the infrared detectors that NEOCam would use.

The report concluded that planetary defense missions like NEOCam should not have to compete with other planetary science missions in the Discovery program, in part because planetary defense was not mentioned in the latest decadal survey of the field. “As a result, there is a bias against selection of planetary defense-focused missions in this program,” the report stated.
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 07/08/2019 05:59 pm
Probably just me but it seems funny to think of a working observatory as also being a world heritage site.

https://www.theguardian.com/culture/2019/jul/07/jodrell-bank-observatory-becomes-world-heritage-site

Few working observatories have the history, including one of the greatest press scoops of the last century (https://www.airspacemag.com/daily-planet/scooping-the-soviets-16255658/)!

ETA YouTube video (https://www.youtube.com/watch?v=okhmYbuK0Fk)
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/08/2019 06:28 pm
What also amazed me is it’s still the third largest single dish radio telescope.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/09/2019 05:11 pm
 Supercomputer shows 'Chameleon Theory' could change how we think about gravity (https://www.eurekalert.org/pub_releases/2019-07/du-ss070819.php)

Quote
Supercomputer simulations of galaxies have shown that Einstein's theory of General Relativity might not be the only way to explain how gravity works or how galaxies form.

Physicists at Durham University, UK, simulated the cosmos using an alternative model for gravity - f(R)-gravity, a so called Chameleon Theory.

The resulting images produced by the simulation show that galaxies like our Milky Way could still form in the universe even with different laws of gravity.

The findings show the viability of Chameleon Theory - so called because it changes behaviour according to the environment - as an alternative to General Relativity in explaining the formation of structures in the universe.

The research could also help further understanding of dark energy - the mysterious substance that is accelerating the expansion rate of the universe.

Could Vacuum Physics Be Revealed By Laser-Driven Microbubble? (https://scienmag.com/could-vacuum-physics-be-revealed-by-laser-driven-microbubble/)

Quote
Scientists at Osaka University discovered a novel mechanism which they refer to as microbubble implosion (MBI) in 2018. In MBI, super-high energy hydrogen ions (relativistic protons) are emitted at the moment when bubbles shrink to atomic size through the irradiation of hydrides with micron-sized spherical bubbles by ultraintense, ultrashort laser pulses.

In this study, the group led by Masakatsu Murakami confirmed that during MBI, an ultrahigh electrostatic field close to the Schwinger field could be achieved because micron-sized bubbles embedded in a solid hydride target implode to have nanometer-sized diameters upon ionization.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/09/2019 10:07 pm
The Mysterious Star HD139139 with Dr. Andrew Vanderburg:

https://youtu.be/Ml8BsjSdPWo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/10/2019 01:30 pm
How Sonic Black Holes Could Confirm Hawking’s Radiation:

https://youtu.be/F8bZ-vt1WwE
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/10/2019 05:59 pm
Quote
Astronomers have spotted an unusual asteroid with the shortest "year" known for any asteroid. The rocky body, dubbed 2019 LF6, is about a kilometer in size and circles the sun roughly every 151 days. In its orbit, the asteroid swings out beyond Venus and, at times, comes closer in than Mercury, which circles the sun every 88 days. 2019 LF6 is one of only 20 known "Atira" asteroids, whose orbits fall entirely within Earth's.

https://www.caltech.edu/about/news/ztf-spots-asteroid-shortest-year
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/11/2019 09:39 pm
Quote
Astronomers using the NASA/ESA Hubble Space Telescope have observed an unexpected thin disc of material encircling a supermassive black hole at the heart of the spiral galaxy NGC 3147, located 130 million light-years away.

http://sci.esa.int/hubble/61446-hubble-discovers-mysterious-black-hole-disc-heic1913/
Title: Re: Astronomy & Planetary Science Thread
Post by: Eric Hedman on 07/15/2019 11:12 pm
The protests continue on the construction of the Thirty Meter Telescope:

https://apnews.com/3459159e3fba48f5a10812b1064db26a (https://apnews.com/3459159e3fba48f5a10812b1064db26a)
Title: Re: Astronomy & Planetary Science Thread
Post by: Eric Hedman on 07/16/2019 06:53 pm
The Ice Cube Neutrino Detector is getting a $37 million dollar upgrade:

https://news.wisc.edu/icecube-antarctic-neutrino-detector-to-get-37-million-upgrade/ (https://news.wisc.edu/icecube-antarctic-neutrino-detector-to-get-37-million-upgrade/)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/19/2019 08:22 pm
Quote
Earth's scorching core is not a loner — it has been caught mingling with other, underworldly layers. That's according to a new study that found the innermost part of the planet leaks some of its contents into mantle plumes, some of which eventually reach Earth's surface.

This discovery helps settle a debate that's been raging for decades: whether the core and mantle exchange any material, the researchers said.

https://www.livescience.com/65968-earth-leaky-core.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/22/2019 09:55 pm
Quote
That allowed them to analyze what kind of star BLG-0950L is, and they found it to be an orange K-type dwarf with about 0.6 times the mass of the Sun, and lying about 7,000 light years away. The planet therefore has a mass of about 40 times the Earth, and orbits the star about 380 million kilometers out. That's farther out than the star's snow line…

… right in the middle of that hypothesized mass desert between Neptune and Saturn.

So that's interesting. The hypothesis says there shouldn't be planets there, yet BLG-0950Lb is. Does this prove the hypothesis wrong?

https://www.syfy.com/syfywire/astronomers-find-a-rare-super-neptune-thanks-to-einstein
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/23/2019 08:02 pm
From Cool Worlds - The Exoplanet Multiplicity Distribution:

https://youtu.be/pcP8mp8ev0M
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/23/2019 08:57 pm
Quote
A team of astronomers led by the Center for Astrophysics | Harvard &amp; Smithsonian have updated and confirmed self-lensing binary star KOI-3278's companion to be a white dwarf star by pitting Einstein against Newton.

Discovered as the first self-lensing binary star system in 2014 by University of Washington scientists, KOI-3278’s behavior was originally reported as a result of microlensing based on periodic increases in brightness as the potential white dwarf companion passed in front of the G star, and dips in brightness as it passed behind the star.

https://www.cfa.harvard.edu/news/2019-16
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/24/2019 06:50 am
Quote
In a recent opinion piece for Scientific American, physicists Grigoris Panoutsopoulos and Frank Zimmermann advocate spending billions of dollars on what would be the largest particle collider yet—the Future Circular Collider (FCC), currently planned at CERN, near Geneva. Their argument, in a nutshell, is that we should stop asking particle physicists to justify large investments into their research area and just give them money. I strongly disagree.

https://blogs.scientificamerican.com/observations/which-should-come-first-in-physics-theory-or-experiment-glad-you-asked/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/25/2019 06:16 pm
Quote
According to the district magistrate, a group of farmers found the 13-kg meteorite in a hole created by the impact while they were working in the fields in Mahadeva village.

https://thewire.in/space/suspected-meteorite-chunk-lands-bihar-madhubani-district
Title: Re: Astronomy & Planetary Science Thread
Post by: Mongo62 on 07/26/2019 02:37 pm
Quote
In a recent opinion piece for Scientific American, physicists Grigoris Panoutsopoulos and Frank Zimmermann advocate spending billions of dollars on what would be the largest particle collider yet—the Future Circular Collider (FCC), currently planned at CERN, near Geneva. Their argument, in a nutshell, is that we should stop asking particle physicists to justify large investments into their research area and just give them money. I strongly disagree.

https://blogs.scientificamerican.com/observations/which-should-come-first-in-physics-theory-or-experiment-glad-you-asked/

No, a next larger particle collider will not tell us anything about the creation of the universe (http://backreaction.blogspot.com/2019/06/no-next-larger-particle-collider-will.html)

Quote
A few days ago, Scientific American ran a piece by a CERN physicist and a philosopher about particle physicists’ plans to spend $20 billion on a next larger particle collider, the Future Circular Collider (FCC). To make their case, the authors have dug up a quote from 1977 and ignored the 40 years after this, which is a truly excellent illustration of all that’s wrong with particle physics at the moment.

I currently don’t have time to go through this in detail, but let me pick the most egregious mistake. It’s right in the opening paragraph where the authors claim that a next larger collider would tell us something about the creation of the universe:
“[P]article physics strives to push a diverse range of experimental approaches from which we may glean new answers to fundamental questions regarding the creation of the universe and the nature of the mysterious and elusive dark matter.

Such an endeavor requires a post-LHC particle collider with an energy capability significantly greater than that of previous colliders.”

We previously encountered this sales-pitch in CERN’s marketing video for theFCC, which claimed that the collider would probe the beginning of the universe.

But neither the LHC nor the FCC will tell us anything about the “beginning” or “creation” of the universe.

What these colliders can do is create nuclear matter at high density by slamming heavy atomic nuclei into each other. Such matter probably also existed in the early universe. However, even collisions of large nuclei create merely tiny blobs of such nuclear matter, and these blobs fall apart almost immediately. In case you prefer numbers over words, they last about 10-23 seconds.

This situation is nothing like the soup of plasma in the expanding space of the early universe. It is therefore highly questionable already that these experiments can tell us much about what happened back then.

Even optimistically, the nuclear matter that the FCC can produce has a density about 70 orders of magnitude below the density at the beginning of the universe.

And even if you are willing to ignore the tiny blobs and their immediate decay and the 70 orders of magnitude, then the experiments still tell us nothing about the creation of this matter, and certainly not about the creation of the universe.

The argument that large colliders can teach us anything about the beginning, origin, or creation of the universe is manifestly false. The authors of this article either knew this and decided to lie to their readers, or they didn’t know it, in which case they have begun to believe their own institution’s marketing. I’m not sure which is worse.

And as I have said many times before, there is no reason to think a next larger collider would find evidence of dark matter particles. Somewhat ironically, the authors spend the rest of their article arguing against theoretical arguments, but of course the appeal to dark matter is a bona-fide theoretical argument.

In any case, it pains me to see not only that particle physicists are still engaging in false marketing, but that Scientific American plays along with it.

How about sticking with the truth? The truth is that a next larger collider costs a shitload lot of money and will most likely not teach us much. If progress in the foundations of physics is what you want, this is not the way forward.
Title: Re: Astronomy & Planetary Science Thread
Post by: Eric Hedman on 07/27/2019 04:55 pm
The protests continue at the Thirty Meter Telescope delaying the start of construction.  Now the Rock is involved:

https://www.foxnews.com/entertainment/dwayne-the-rock-johnson-joins-protesters-in-hawaii (https://www.foxnews.com/entertainment/dwayne-the-rock-johnson-joins-protesters-in-hawaii)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/28/2019 03:10 pm
https://youtu.be/xTHngFzi8mY
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/29/2019 03:02 pm
Quote
Gas-giant planets orbiting close to other stars have powerful magnetic fields, many times stronger than our own Jupiter, according to a new study by a team of astrophysicists. It is the first time the strength of these fields has been calculated from observations.

The team, led by Wilson Cauley of the University of Colorado, also includes associate professor Evgenya Shkolnik of Arizona State University's School of Earth and Space Exploration. The other researchers are Joe Llama of Northern Arizona University and Antonino Lanza of the Astrophysical Observatory of Catania in Italy. Their report was published July 22 in Nature Astronomy.

https://www.eurekalert.org/pub_releases/2019-07/asu-amf071919.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/30/2019 03:50 pm
Quote
A new study spearheaded by Earth scientists at the University of Cologne’s Institute of Geology and Mineralogy has constrained the age of the Moon to approximately 50 million years after the formation of the solar system. After the formation of the solar system, 4.56 billion years ago, the Moon formed approximately 4.51 billion years ago. The new study has thus determined that the Moon is significantly older than previously believed – earlier research had estimated the Moon to have formed approximately 150 million years after solar system’s formation. To achieve these results, the scientists analysed the chemical composition of a diverse range of samples collected during the Apollo missions. The study ‘Early Moon formation inferred from hafnium–tungsten systematics’ was published in Nature Geoscience.

http://www.portal.uni-koeln.de/9015.html?&amp;L=1&amp;tx_news_pi1%5Bcontroller%5D=News&amp;tx_news_pi1%5Baction%5D=detail&amp;tx_news_pi1%5Bnews%5D=5428&amp;cHash=55aa00c97b4c5221c780d120dbdbdfb5
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 07/31/2019 06:33 am
Quote
We report on the highest energy photons from the Crab Nebula observed by the Tibet air shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an air shower, we successfully suppress 99.92% of the cosmic-ray background events with energies
E&gt;100TeV. As a result, we observed 24 photonlike events with E&gt;100TeV
against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E&gt;
100TeVfrom an astrophysical source.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.051101
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/31/2019 03:54 pm
Recent research suggests that major meteorite impact events into a Late Hesperian/Early Amazonian ocean likely produced a megatsunami that would have resurfaced coastal areas in northwestern Arabia Terra. The orientations of the associated lobate deposits, a conspicuous type of landforms called Thumbprint Terrain, suggests that if an impact event triggered the megatsunami, the most likely location of the source crater is within the northern plains regions situated north of Arabia Terra. This study focuses on the identification of impact craters that impacted into the ocean and are likely to have produced the tsunami. We selected 10 complex impact craters, based on their diameters, location, and geomorphic characteristics. Of those, the Late Hesperian ~120kmdiameter Lomonosov crater exhibits a unique topographic plan view asymmetry (compared to other similarsized and similaraged craters in the northern plains such as Micoud, Korolev, and Milankovic). We attribute its broad and shallow rim, in part, to an impact into a shallow ocean as well as its subsequent erosion from the collapsing transient water cavity. The likely marine formation of the Lomonosov crater, and the apparent agreement in its age with that of the Thumbprint Terrain unit (~3 Ga), strongly suggests that it was the source crater of the tsunami. These results have implications for the stability of a late northern ocean on Mars.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006008
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/01/2019 08:02 pm
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Rather than being flat as a Frisbee, the Milky Way’s star-studded disk is twisted and warped, according to a new three-dimensional map of our home galaxy. If viewed from the side, the spiral arms girdling our galaxy’s bulging core would resemble a record bent into an S shape, or a softly poached egg sliding off a slotted spoon.

https://www.nationalgeographic.com/science/2019/08/milky-way-galaxy-has-warped-disk-star-map-confirms/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/02/2019 07:27 pm
Turning Earth Into a Telescope - The Terrascope:

https://youtu.be/jgOTZe07eHA
Title: Re: Astronomy & Planetary Science Thread
Post by: aceshigh on 08/02/2019 11:13 pm
i´ve subscribed to that channel a few months ago.

He also came with the idea of the Halo Drive, that was featured on Centauri Dreams.


Anyway, it's a pleasant experience to hear he talking.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/05/2019 05:15 pm
https://youtu.be/OyRTIB7TNwg
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/06/2019 07:27 am
The Moon and Mercury May Have Thick Ice Deposits

Earth’s Moon and Mercury, the closest planet to the Sun, may contain significantly more water ice than previously thought, according to a new analysis of data from NASA’s LRO and MESSENGER spacecraft.

The potential ice deposits are found in craters near the poles of both worlds. On the Moon, "We found shallow craters tend to be located in areas where surface ice was previously detected near the south pole of the Moon, and inferred this shallowing is most likely due to the presence of buried thick ice deposits,” said lead author Lior Rubanenko of the University of California, Los Angeles.

In the past, telescopic observations and orbiting spacecraft have found glacier-like ice deposits on Mercury, but as of yet not on the Moon. The new work raises the possibility that thick ice-rich deposits also exist on the Moon. The research may not only help resolve the question regarding the Moon’s apparent low ice abundance relative to Mercury, but it could also have practical applications: “If confirmed, this potential reservoir of frozen water on the Moon may be sufficiently massive to sustain long-term lunar exploration,” said Noah Petro, Lunar Reconnaissance Orbiter Project Scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The poles of Mercury and the Moon are among the coldest places in our solar system. Unlike Earth, the spin axes of Mercury and the Moon are oriented such that, in their polar regions, the Sun never rises high above the horizon. Consequently, polar topographic depressions, such as impact craters, never see the Sun. For decades it has been postulated these so-called permanently shadowed regions are so cold that any ice trapped within them can potentially survive for billions of years.

Previous observations of the poles of Mercury with Earth-based radar revealed a signature characteristic of thick, pure ice deposits. Later, MESSENGER – the MErcury Surface, Space ENvironment, GEochemistry and Ranging spacecraft – imaged these ice deposits. “We showed Mercury’s polar deposits to be dominantly composed of water ice and extensively distributed in both Mercury’s north and south polar regions,” said Nancy Chabot, instrument scientist for MESSENGER’s Mercury Dual Imaging System from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “Mercury’s ice deposits appear to be much less patchy than those on the Moon, and relatively fresh, perhaps emplaced or refreshed within the last tens of millions of years.”

Previous radar and imaging studies of the Moon, whose polar thermal environments are very similar to those of Mercury, found only patchy, shallow ice deposits. This outstanding difference served as the motivation for the UCLA researchers’ work – a comparative analysis of polar craters on Mercury and the Moon to delve into this difference between the two worlds. The research was published July 22 in Nature Geoscience.

The airless surfaces of Mercury and the Moon are scarred by many impact craters. These craters form when meteoroids or comets impact the surface. The team analyzed simple craters that are formed by smaller, less energetic impactors. These depressions are held together by the strength of the surface dust layer, or regolith and tend to be more circular and symmetrical than large craters. The UCLA scientists exploited this inherent symmetry to estimate the thickness of ice trapped within simple craters.

The study used elevation data obtained by MESSENGER and LRO to measure approximately 15,000 simple craters with diameters ranging from 2.5 km to 15 km (about 1.5 miles to 9.3 miles) on Mercury and the Moon. Researchers found that craters become up to 10% shallower near the north pole of Mercury and the south pole of the Moon, but not the north pole of the Moon.

The authors concluded that the most probable explanation for these shallower craters is the accumulation of previously undetected thick ice deposits on both worlds. Supporting this conclusion, the researchers found that the pole-facing slopes of these craters are slightly shallower than their equator-facing slopes, and that the shallowing is more significant in regions that promote ice stability because of Mercury’s orbit around the Sun. The topographic signal detected by the scientists is relatively more prominent in smaller simple craters, but does not preclude the possibility that ice may be more widespread in larger craters across the lunar pole.

Additionally, unlike Mercury, where the ice has been shown to be nearly pure, the deposits detected on the Moon are most likely mixed with the regolith, possibly in a layered formation. The typical age of the simple craters examined by the researchers indicates they could potentially accumulate ice that was later mixed with overlying regolith over long time scales. The scientists found that these inferred buried ice deposits are correlated with the locations of already detected surface ice. This finding could imply that the exposed ice deposits may be exhumed, or they could result from molecular diffusion from depth.

The research was funded by the LRO and MESSENGER missions. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the Moon. MESSENGER was managed by the Johns Hopkins University Applied Physics Laboratory. The spacecraft was launched Aug 3, 2004, and began orbiting Mercury on March 18, 2011. The mission ended with a planned impact on the surface of Mercury on April 30, 2015. NASA is leading a sustainable return to the Moon with commercial and international partners to expand human presence in space and bring back new knowledge and opportunities.

Bill Steigerwald / Nancy Jones
NASA's Goddard Space Flight Center, Greenbelt, Md.
301-286-8955 / 301-286-0039
[email protected] / [email protected]
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/06/2019 04:47 pm
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This is still unclear. But, in a new paper just published, astronomers have announced they found a brown dwarf smack in the middle of the "desert" region.

The brown dwarf (let me call them BD for short) is called EPIC 212036875b (let's say EPIC 212b, because my fingers are already tired typing that out), and was discovered in data from the Kepler space telescope, designed to look for exoplanets. It's about 1,000 light years away, and it orbits a star that's much like the Sun, though somewhat more massive and hotter.

EPIC 212b is a fascinating object. It was seen to transit its host star, passing directly in front of it as seen from Earth. The amount of light it blocks gives its size, which is about 0.87 times Jupiter's — so it's smaller than our own biggest planet! As it orbits the star its gravity tugs on it, and that can be detected using other telescopes, which can be used to get the mass. Observations of EPIC 212b indicate its mass is a whopping 52 times Jupiter's, putting it toward the upper end of the mass range of BDs.

https://www.syfy.com/syfywire/a-very-dense-oasis-in-the-brown-dwarf-desert

Here’s the paper referred to in the above article:

https://arxiv.org/pdf/1903.03118.pdf
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/07/2019 03:25 pm
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Some stars moving fast enough to escape the galaxy likely come from a never before seen class of intermediate-mass black holes

https://www.scientificamerican.com/article/midsize-black-holes-may-explain-the-milky-ways-speediest-stars/

Here’s the related paper:

https://arxiv.org/abs/1907.06375

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Black holes can get pretty big, but there's a special class that is the biggest of the big, absolute yawning monster black holes. And astronomers seem to have found an absolute specimen, clocking in at 40 billion times the mass of the Sun.

https://www.sciencealert.com/an-absolutely-gargantuan-black-hole-has-been-found-as-massive-as-40-billion-suns

Here’s the related paper:

https://arxiv.org/abs/1907.10608
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/07/2019 10:03 pm
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In new research led by the University of Warwick, scientists have determined the best candidate remnant stars to search for relics of planets, based upon the likelihood of the stars hosting surviving planetary cores and the strength of the radio signal that we can tune in to.

https://ras.ac.uk/news-and-press/news/dead-planets-can-broadcast-billion-years
 
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/08/2019 03:07 pm
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Using ALMA, the Atacama Large Millimeter/submillimeter Array, astronomers have done just that: They made very precise measurements of the central supermassive black hole in a galaxy called NGC 3258, and found it to be a staggering 2.25 billion times the mass of the Sun!

https://www.syfy.com/syfywire/measuring-a-monster-the-two-billion-solar-mass-black-hole-in-ngc-3258

Here’s the related paper:

https://arxiv.org/pdf/1906.06267.pdf

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According to a new paper, the origins of dark matter may be more peculiar than we know. Perhaps, they were particles that appeared in a very brief period of time, just fractions of fractions of a second, before the Big Bang.

https://www.sciencealert.com/new-study-brings-receipts-to-demonstrate-dark-matter-may-be-older-than-the-big-bang

Here’s the paper:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.061302

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/09/2019 06:36 am
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As Texas amateur astronomer Ethan Chappel looked up at the sky for Perseid meteors on Wednesday night (August 7th), little did he know his Celestron 8 telescope was capturing the possible impact of a much larger "meteor" at Jupiter. After running the camera data through a program designed to alert the user to just such transient events, Chappel spotted a flash of light in the planet's South Equatorial Belt (SEB). It expanded from a pinpoint to a small dot before fading away — telltale signs of a possible impact based on previous events observed at Jupiter.

Quote
To get you started, here are a few UT times when the impact site will cross Jupiter's CM, courtesy of Marc Delcroix. They take the site's drift into account. Because of Jupiter's fast rotation, the site rolls into view at least twice a day, hence the two (or three) times shown for each date. System II longitudes are shown in parentheses:

2019 Aug 09:   07:21 (28°)   17:19 (30°)
2019 Aug 10:   03:17 (31°)   13:15 (33°)   23:13 (34°)
2019 Aug 11:   09:11 (35°)   19:08 (36°)
2019 Aug 12:   05:06 (37°)   15:04 (39°)
2019 Aug 13:   01:02 (40°)   11:00 (42°)   20:58 (43°)
2019 Aug 14:   06:56 (44°)   16:54 (46°)

https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/texas-amateur-detects-possible-impact-on-jupiter/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/09/2019 07:46 pm
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Scientists found evidence of dust produced in nearby supernovae hiding under a thousand pounds of Antarctic snow, according to new research.

Our solar system is more than just the Sun, planets, moons, and asteroids—it’s full of dust, much of which might originate from interstellar sources. A team of scientists in Australia, Germany, and Austria hopes to find the elemental signature of this dust here on Earth in order to better understand the environment through which the solar system is moving.

https://gizmodo.com/supernovae-could-have-left-radioactive-dust-in-antarcti-1837099757
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/11/2019 07:08 pm
Jason Momoa has joined those protesting against TMT.

https://www.cbr.com/jason-momoa-aquaman-2-tmt-protest/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/12/2019 07:51 pm
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The supermassive black hole at the heart of the Milky Way, Sagittarius A*, is relatively quiet. It's not an active nucleus, spewing light and heat into the space around it; most of the time, the black hole's activity is low key, with minimal fluctuations in its brightness.

Most of the time. Recently, astronomers caught it going absolutely bananas, suddenly growing 75 times brighter before subsiding back to normal levels. That's the brightest we've ever seen Sgr A* in near-infrared wavelengths.

"I was pretty surprised at first and then very excited," astronomer Tuan Do of the University of California Los Angeles told ScienceAlert.

https://www.sciencealert.com/our-galaxy-s-supermassive-black-hole-just-mysteriously-got-really-really-bright

Here’s the related paper:

https://arxiv.org/abs/1908.01777
Title: Re: Astronomy & Planetary Science Thread
Post by: jgoldader on 08/13/2019 03:43 pm
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The supermassive black hole at the heart of the Milky Way, Sagittarius A*, is relatively quiet. [...]

Most of the time. Recently, astronomers caught it going absolutely bananas, suddenly growing 75 times brighter before subsiding back to normal levels. That's the brightest we've ever seen Sgr A* in near-infrared wavelengths.
[...]
Here’s the related paper:

https://arxiv.org/abs/1908.01777

One wonders if Sgr A* was doing this when the Event Horizon Telescope was observing it, that would help explain the difficult data analysis.  It's fascinating to see this kind of variability.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/13/2019 04:00 pm
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In a paper published today in the journal, Nature Astronomy, a team from Monash University, the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), McGill University in Canada, and the University of Tasmania, studied the Vela Pulsar, a neutron star in the southern sky, that is 1,000 light years away.

According to the paper's first author, Dr. Greg Ashton, from the Monash School of Physics and Astronomy, and a member of OzGrav, Vela is famous—not only because only 5% of pulsars are known to glitch but also because Vela "glitches" about once every three years, making it a favourite of "glitch hunters" like Dr. Ashton and his colleague, Dr. Paul Lasky, also from Monash and OzGrav.

https://m.phys.org/news/2019-08-glitch-neutron-star-reveals-hidden.html (https://m.phys.org/news/2019-08-glitch-neutron-star-reveals-hidden.html)
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/14/2019 06:50 am
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The supermassive black hole at the heart of the Milky Way, Sagittarius A*, is relatively quiet. [...]

Most of the time. Recently, astronomers caught it going absolutely bananas, suddenly growing 75 times brighter before subsiding back to normal levels. That's the brightest we've ever seen Sgr A* in near-infrared wavelengths.
[...]
Here’s the related paper:

https://arxiv.org/abs/1908.01777

One wonders if Sgr A* was doing this when the Event Horizon Telescope was observing it, that would help explain the difficult data analysis.  It's fascinating to see this kind of variability.

Worth having a look at this thread by one of the authors of the paper for more on this:

https://mobile.twitter.com/quantumpenguin/status/1160368687590727680
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/14/2019 03:05 pm
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Glowing planets elsewhere in the universe might be home to alien life, scientists have said.

We might be able to spot evidence of aliens on other planets by looking out for the distinctive glow, allowing astronomers to understand distant worlds' life through Earth's telescopes, they say.

The alien worlds might be glowing with spectacular and beautiful colours, the researchers say – a light show that could be the result of a process that keeps life on those planets from being destroyed by radiation.

https://www.independent.co.uk/life-style/gadgets-and-tech/news/alien-life-proof-universe-fluorescent-glow-ultraviolet-rays-biospheres-a9057896.html

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A "Jurassic World" of volcanoes has been discovered a mile beneath the surface of Earth. Researchers in Australia have found around 100 volcanoes covering an area larger than Delaware. They emerged between 160 and 180 million years ago and were subsequently buried beneath sedimentary locks, becoming lost to time.

https://www.newsweek.com/jurassic-world-volcanoes-beneath-earth-1454211

Here’s the associated paper:

https://www.sciencedirect.com/science/article/pii/S1342937X19302023?via%3Dihub
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/14/2019 07:32 pm
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Jupiter harbors a deep mystery: Rather than the distinct core scientists expected, it has a fuzzy center, according to recent observations by NASA’s Juno spacecraft, which extends for up to half the planet’s radius.

One possible explanation is a cataclysmic head-on collision some 4.5 billion years ago between a young Jupiter and one of the many large protoplanets that likely populated the early solar system, planetary scientists report today in Nature. Such an event would have seen Jupiter absorb the protoplanet, which would have been 10 times Earth’s mass, causing their two dense cores to combine and diffuse after only 10 hours, as seen in the simulation above. Over time, cooling and winds could sweep some of the fuzzy core upward, explaining Jupiter’s puzzling enrichment in elements like carbon and nitrogen close to its surface.

https://www.sciencemag.org/news/2019/08/cataclysmic-collision-could-explain-jupiter-s-fuzzy-core
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/15/2019 08:06 am
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One of the biggest mysteries out there in the Universe is inching closer to answers. An astonishing eight new repeating radio signals known as fast radio bursts (FRBs) have been detected flaring from deep space.

Quote
That's where the broader scientific community comes in. Just today, a different team of researchers, including Ravi, announced they had made headway localising the eight new repeaters to known galaxies, just based on the direction the signals came from.

We can even roughly tell how far away the bursts may have originated based on how dispersed the signal is - the higher these measures, the farther the distance.

In fact, this is where it gets intriguing, because one of the signals, FRB 180916, has the lowest dispersion seen yet, indicating that it could be nearby.

https://www.sciencealert.com/astronomers-have-bagged-a-jaw-dropping-haul-of-eight-new-repeating-fast-radio-bursts

Associated links:

http://www.astronomerstelegram.org/?read=13018

https://arxiv.org/abs/1908.03507
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/15/2019 04:01 pm
I’ve already posted about this news but I thought his analysis was quite interesting.

Quote
One thing that bugs me a bit is that the outcome of the model is heavily dependent on the impact conditions. They had to fiddle with a lot of variables to get the answer to match present-day observations. That’s not a deal-killer, but it’s an indication that you have to be careful making firm conclusions based on the model. If you have to make things just right to get the conclusion you want a lot of scientists will be rightfully skeptical.

But it does have a lot of positives to it — in fact, interestingly, in one way the fine-tuning issue is a pro for the model. Saturn is very different internally than Jupiter, which is a little weird. You’d expect them to be pretty similar if they formed in the same region of the solar system. But maybe Saturn got hit as well, and because the impact was different (maybe the impactor was a different mass, or the impact angle was offset a bit) the outcome was really different. So the sensitivity of the model to different variables actually makes sense for that.

https://www.syfy.com/syfywire/was-jupiters-core-nearly-destroyed-by-a-massive-planetary-impact-while-it-was-still-forming
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/16/2019 05:51 am
Another video from Event Horizon on the Terrascope.

https://youtu.be/OjXN-SmHvC0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/16/2019 03:11 pm
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The event is called SN2016iet, a supernova that was detected on November 14, 2016. It was first spotted in data taken by the space-based Gaia observatory, and was followed-up by the Catalina Real-Time Transient Survey, then Pan-STARRS, and eventually the huge Gemini Telescope to get deep spectra of it. But it didn’t take long to determine that this particular supernova was weird.

And then they found it was really weird.

Most exploding stars get bright over the course of a few days, peak, then decay away over the next few months. SN2016iet didn’t do that: It peaked twice, which right away is bizarre. The second peak occurred about 100 days after the first, and both were phenomenally energetic, blasting out more than ten billion times the Sun’s energy for days at a time. Holy yikes.

But even then it didn’t behave properly. Instead of fading away into obscurity, the supernova continued to shine, fading much more slowly than usual. The astronomers were still able to observe it in spring of this year, more than two years after the initial explosion.

https://www.syfy.com/syfywire/across-the-universe-a-star-exploded-so-violently-that-it-completely-annihilated-itself
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/17/2019 07:56 am
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Research articles reporting significant developments, discoveries, and theories about planets, moons, small bodies, and the interactions among them will soon have a new showcase: The Planetary Science Journal (PSJ). This online publication is being launched by the AAS in conjunction with the Division for Planetary Sciences (DPS). The new journal will publish important research directly relevant to our solar system and other planetary systems, including observational results, theoretical insights, modeling, laboratory studies, instrumentation, and field studies.

https://aas.org/posts/news/2019/08/aas-dps-launch-gold-open-access-planetary-science-journal
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/19/2019 04:51 pm
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ON SEPTEMBER 27, 1971, a nuclear bomb exploded on Russia’s Novaya Zemlya islands. The powerful blast sent waves rippling so deep inside Earth they ricocheted off the inner core, pinging an array of hundreds of mechanical ears some 4,000 miles away in the Montana wilderness. Three years later, that array picked up a signal when a second bomb exploded at nearly the same spot.
This pair of nuclear explosions was part of hundreds of tests detonated during the throes of Cold War fervor. Now, the records of these wiggles are making waves among geologists: They have helped scientists calculate one of the most precise estimates yet of how fast the planet’s inner core is spinning.

https://www.nationalgeographic.com/science/2019/08/earths-inner-core-spinning-surprisingly-slow-nuclear-tests-reveal/

Here’s the related paper:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083774

Quote
A team of astronomers led by Anne-Marie Lagrange, a CNRS researcher at the Institut de Planétologie et d'Astrophysique de Grenoble (CNRS/Université Grenoble Alpes)1, has discovered a second giant planet in orbit around b Pictoris, a star that is relatively young (23 million years old) and close (63.4 light years), and surrounded by a disk of dust.

https://www.sciencedaily.com/releases/2019/08/190819112735.htm
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/20/2019 06:37 am
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Most known terrestrial planets orbit small stars with radii less than 60 per cent of that of the Sun1,2. Theoretical models predict that these planets are more vulnerable to atmospheric loss than their counterparts orbiting Sun-like stars3,4,5,6. To determine whether a thick atmosphere has survived on a small planet, one approach is to search for signatures of atmospheric heat redistribution in its thermal phase curve7,8,9,10. Previous phase curve observations of the super-Earth 55 Cancri e (1.9 Earth radii) showed that its peak brightness is offset from the substellar point (latitude and longitude of 0 degrees)—possibly indicative of atmospheric circulation11. Here we report a phase curve measurement for the smaller, cooler exoplanet LHS 3844b, a 1.3-Earth-radii world in an 11-hour orbit around the small nearby star LHS 3844. The observed phase variation is symmetric and has a large amplitude, implying a dayside brightness temperature of 1,040 ± 40 kelvin and a nightside temperature consistent with zero kelvin (at one standard deviation). Thick atmospheres with surface pressures above 10 bar are ruled out by the data (at three standard deviations), and less-massive atmospheres are susceptible to erosion by stellar wind. The data are well fitted by a bare-rock model with a low Bond albedo (lower than 0.2 at two standard deviations). These results support theoretical predictions that hot terrestrial planets orbiting small stars may not retain substantial atmospheres.

https://www.nature.com/articles/s41586-019-1497-4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/20/2019 06:50 am
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At Oak Ridge National Laboratory in eastern Tennessee, physicist Leah Broussard is trying to open a portal to a parallel universe.

She calls it an “oscillation” that would lead her to “mirror matter,” but the idea is fundamentally the same. In a series of experiments she plans to run at Oak Ridge this summer, Broussard will send a beam of subatomic particles down a 50-foot tunnel, past a powerful magnet and into an impenetrable wall. If the setup is just right — and if the universe cooperates — some of those particles will transform into mirror-image versions of themselves, allowing them to tunnel right through the wall. And if that happens, Broussard will have uncovered the first evidence of a mirror world right alongside our own.

https://www.nbcnews.com/mach/science/scientists-are-searching-mirror-universe-it-could-be-sitting-right-ncna1023206
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/21/2019 09:11 am
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A new study by researchers at Penn State and Brigham Young University provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our sun. Knowing the rate that these potentially habitable planets occur will be important for designing future astronomical missions to characterize nearby rocky planets around sun-like stars that could support life. A paper describing the model appears Aug. 14, in The Astronomical Journal.

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Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of Earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in six stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low as about one planet for every 33 stars, to as high as nearly one planet for every two stars.

https://news.psu.edu/story/583877/2019/08/14/research/how-many-earth-planets-are-around-sun-stars

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The four 1-metre SPECULOOS telescopes at the Paranal Observatory in Chile, designed to Search for habitable Planets EClipsing ULtra-COOL Stars, captured this spectacular view of Centaurus A (NGC 5128), a galaxy 11 million light years from Earth that harbours a 100-million-solar-mass black hole at its core. Discovered in 1826, it is the closest active galactic nucleus and a familiar target for professional and amateur astronomers alike. Researchers attribute the galaxy’s unusual appearance to a collision in the remote past between an elliptical galaxy and a smaller spiral. This image shows red and pink star-forming regions and clusters of young blue stars at top right. The vast dust clouds towards the centre of Centaurus A are slowly being consumed by the central black hole, resulting in powerful radio emissions.

https://astronomynow.com/2019/08/01/planet-hunting-telescope-captures-intriguing-view-of-centaurus-a/
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 08/22/2019 10:25 pm
Quote
Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of Earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in six stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low as about one planet for every 33 stars, to as high as nearly one planet for every two stars.

Presumably by "stars" here they continue to mean sun-like stars? They were careful to specify sun-like stars elsewhere in the article and somewhat unfortunate they (presumably) lapsed here. Of course, planets with 237-500 day orbits would not be in the habitable zone of the vast majority of stars.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/26/2019 07:39 am
Quote
That’s what many participants probably realized earlier this year when we asked them to tweet us suggestions to help name five of the recently discovered moons of Jupiter.
“There are many rules when it comes to how we name moons,” said Carnegie’s Scott Sheppard, who last July announced the discovery of 12 new moons orbiting Jupiter, five of which were the subjects of this contest. “Most notably, Jovian naming conventions require its many moons to be named after characters from Greek and Roman mythology who were either descendants or consorts of Zeus, or Jupiter.”
But there are plenty of other strictures as well, including maximum character lengths and the final letter of each name, depending on the direction of a moon’s orbit.
From February to April, we solicited name suggestions and the submissions ranged from the scholarly to the silly, including some inevitable Moony McMoonFaces and a surprisingly large number of people who felt strongly about naming the moons after a beloved pet. We combed through them all—even the ones that blatantly disregarded the rules—and passed the best ones on to the International Astronomical Union.
Today, the IAU is publishing the winners:

https://carnegiescience.edu/news/results-are-jovian-moon-naming-contest-winners-announced
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/29/2019 06:49 pm
https://www.wired.com/story/how-americas-spooks-seek-to-spy-on-distant-satellites/
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/29/2019 08:47 pm
From Cool Worlds.

An Interplanetary Internet Using Planetary Atmospheres:

https://www.youtube.com/watch?v=F9S21HqfNR0

Rogue Supermassive Black Holes with Yale’s Dr. Michael Tremmel:

https://youtu.be/d2kmL5PQOR4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/30/2019 07:30 pm
Quote
Unexplained shapes seen on Venus, which some scientists have suggested could be signs of alien life, are even more mysterious than we thought.

Researchers studying the Venusian surface have found that the strange dark spots are affecting the planet's climate, after a new breakthrough study.

Scientists have known about the dark "splotches" on the surface for more than a century, and they change over time. But they have never been explained, with some researchers suggesting they could be evidence of life.

“The particles that make up the dark splotches, have been suggested to be ferric chloride, allotropes of sulfur, disulfur dioxide and so on, but none of these, so far, are able to satisfactorily explain their formation and absorption properties,” said Yeon Joo Lee, the senior author of the new report, in a statement.

https://www.independent.co.uk/life-style/gadgets-and-tech/news/venus-shapes-climate-weather-albedo-breakthrough-discovery-space-a9085916.html
Title: Re: Astronomy & Planetary Science Thread
Post by: tyrred on 08/31/2019 07:53 am
Quote
Unexplained shapes seen on Venus, which some scientists have suggested could be signs of alien life, are even more mysterious than we thought.

Researchers studying the Venusian surface have found that the strange dark spots are affecting the planet's climate, after a new breakthrough study.

Scientists have known about the dark "splotches" on the surface for more than a century, and they change over time. But they have never been explained, with some researchers suggesting they could be evidence of life.

“The particles that make up the dark splotches, have been suggested to be ferric chloride, allotropes of sulfur, disulfur dioxide and so on, but none of these, so far, are able to satisfactorily explain their formation and absorption properties,” said Yeon Joo Lee, the senior author of the new report, in a statement.

https://www.independent.co.uk/life-style/gadgets-and-tech/news/venus-shapes-climate-weather-albedo-breakthrough-discovery-space-a9085916.html

What types of experiments from orbit can help ascertain the composition of these anomalies? Can spectral analysis be ascertained from radar?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/31/2019 08:57 am
Quote
Unexplained shapes seen on Venus, which some scientists have suggested could be signs of alien life, are even more mysterious than we thought.

Researchers studying the Venusian surface have found that the strange dark spots are affecting the planet's climate, after a new breakthrough study.

Scientists have known about the dark "splotches" on the surface for more than a century, and they change over time. But they have never been explained, with some researchers suggesting they could be evidence of life.

“The particles that make up the dark splotches, have been suggested to be ferric chloride, allotropes of sulfur, disulfur dioxide and so on, but none of these, so far, are able to satisfactorily explain their formation and absorption properties,” said Yeon Joo Lee, the senior author of the new report, in a statement.

https://www.independent.co.uk/life-style/gadgets-and-tech/news/venus-shapes-climate-weather-albedo-breakthrough-discovery-space-a9085916.html

What types of experiments from orbit can help ascertain the composition of these anomalies? Can spectral analysis be ascertained from radar?

This appears to be the related paper. Was having trouble finding it probably because it was actually published in September 2018.

https://www.liebertpub.com/doi/full/10.1089/ast.2017.1783
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/01/2019 06:45 am
Detecting Alien Biofluorescence:

https://youtu.be/MvQxkuKbMmk
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/02/2019 07:31 pm
Quote
Scientists have discovered a mass die-off that took place two billion years ago—with up to 99.5 percent of life on Earth disappearing. The massive die-off saw more of the planet's biosphere vanish than when the dinosaurs were wiped off the face of the planet 65 million years ago, researchers say.

Normally, massive die-off events can be tracked through the fossil record—animals exist, then they do not. However, in times before complex life existed, understanding these events becomes more difficult—the microorganisms that made up the planet's biota cannot be traced in the same way.

https://www.newsweek.com/earth-massive-die-off-dinosaur-extinction-1457228

Here’s the related paper:

https://www.pnas.org/content/116/35/17207

Quote
I mean that literally. Eccentricity is an astronomy term for how much an object’s orbit deviates from a circle. It's originally an old math term to describe an ellipse. An eccentricity of 0 is a perfect circle, and the ellipticity gets more pronounced as the eccentricity gets higher (up to a value of 1; at exactly 1 you have a parabola, and if it’s &gt;1 it's a hyperbola).

Earth's orbit has an eccentricity of &lt; 0.02. The most eccentric planet in our solar system is Mercury, with an eccentricity of 0.205; even Pluto's wildly eccentric orbit has a value of just 0.244.

Astronomers have just discovered an exoplanet with an orbital eccentricity of 0.84. Holy wow. It gets as close to its parent star as about 440 million kilometers (roughly where the asteroid belt is in our solar system) and as far as 5 billion kilometers — farther from its star than Neptune gets from the Sun!

https://www.syfy.com/syfywire/an-exoplanet-dive-bombs-its-star
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/03/2019 03:11 pm
Quote
Govert Schilling takes a tour of the Canada Hydrogen Intensity Mapping Experiment to find out how it's searching the sky for cosmic explosions known as fast radio bursts.

https://www.skyatnightmagazine.com/space-science/chime-telescope-hunt-fast-radio-bursts/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/04/2019 06:41 am
Quote
Last December, scientists discovered an “active” asteroid within the asteroid belt, sandwiched between the orbits of Mars and Jupiter. The space rock, designated by astronomers as 6478 Gault, appeared to be leaving two trails of dust in its wake — active behavior that is associated with comets but rarely seen in asteroids.

While astronomers are still puzzling over the cause of Gault’s comet-like activity, an MIT-led team now reports that it has caught the asteroid in the act of changing color, in the near-infrared spectrum, from red to blue. It is the first time scientists have observed a color-shifting asteroid, in real-time.

http://news.mit.edu/2019/asteroid-changing-color-first-0830
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/04/2019 10:04 pm
Quote
Scientists have discovered a new mineral, one never before seen in nature, lodged inside a meteorite found near Wedderburn in central Victoria.

They believe the mineral was likely forged in the molten core of an ancient planet long since destroyed.

https://www.smh.com.au/national/victoria/this-meteorite-came-from-the-core-of-another-planet-inside-it-a-new-mineral-20190830-p52mhg.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/05/2019 06:34 am
Quote
Two recent observations of the nearby galaxy NGC 6946 with NuSTAR, one simultaneous with an XMM-Newton observation, provide an opportunity to examine its population of bright accreting sources from a broadband perspective. We study the three known ultraluminous X-ray sources (ULXs) in the galaxy, and find that ULX-1 and ULX-2 have very steep power-law spectra with ${\rm{\Gamma }}={3.6}_{-0.3}^{+0.4}$ in both cases. Their properties are consistent with being super-Eddington accreting sources with the majority of their hard emission obscured and down-scattered. ULX-3 (NGC 6946 X-1) is significantly detected by both XMM-Newton and NuSTAR at L X = (6.5 ± 0.1) × 1039 erg s−1, and has a power-law spectrum with Γ = 2.51 ± 0.05. We are unable to identify a high-energy break in its spectrum like that found in other ULXs, but the soft spectrum likely hinders our ability to detect one. We also characterize the new source, ULX-4, which is only detected in the joint XMM-Newton and NuSTAR observation, at L X = (2.27 ± 0.07) × 1039 erg s−1, and is absent in a Chandra observation 10 days later. It has a very hard cutoff power-law spectrum with Γ = 0.7 ± 0.1 and ${E}_{\mathrm{cut}}={11}_{-4}^{+9}$ keV. We do not detect pulsations from ULX-4, but its transient nature can be explained either as a neutron star ULX briefly leaving the propeller regime or as a micro-tidal disruption event induced by a stellar-mass compact object.

https://iopscience.iop.org/article/10.3847/1538-4357/ab20cd
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/08/2019 09:30 am
Quote
In fact, Nakayama calculates that the hot tectonic rifts on an ocean world would be so efficient in driving weathering of their sea floor rocks that they would remove so much carbon dioxide from their atmosphere that they would plunge into cold climates.

If Nakayama is right, many of the ocean worlds in habitable orbits throughout the galaxy could in fact be snowball worlds.

https://www.skyatnightmagazine.com/space-science/could-water-rich-exoplanets-experience-extreme-cooling/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/10/2019 05:53 am
Quote
The Cassini mission discovered lakes and seas comprising mostly methane in the polar regions of Titan. Lakes of liquid nitrogen may have existed during the epochs of Titan’s past in which methane was photochemically depleted, leaving a nearly pure molecular nitrogen atmosphere and, thus, far colder temperatures. The modern-day small lake basins with sharp edges have been suggested to originate from dissolution processes, due to their morphological similarity to terrestrial karstic lakes. Here we analyse the morphology of the small lake basins that feature raised rims to elucidate their origin, using delay-Doppler processed altimetric and bathymetric data acquired during the last close flyby of Titan by the Cassini spacecraft. We find that the morphology of the raised-rim basins is analogous to that of explosion craters from magma–water interaction on Earth and therefore propose that these basins are from near-surface vapour explosions, rather than karstic. We calculate that the phase transition of liquid nitrogen in the near subsurface during a warming event can generate explosions sufficient to form the basins. Hence, we suggest that raised-rim basins are evidence for one or more warming events terminating a nitrogen-dominated cold episode on Titan.

https://www.nature.com/articles/s41561-019-0429-0
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/10/2019 06:42 am
Quote
Based on a detailed study of the polarisation information of the received emission, it was possible to apply a 50-year old model, predicting that the polarisation properties encoded information about the geometry of the pulsar.

The pulsar data validated the model and also allowed the team to measure the rate of precession with only 5 percent uncertainty level, tighter than the precession rate measurement in the Double Pulsar system, a reference system for such tests so far. The measured value agrees perfectly with the prediction of Einstein’s theory.

https://astronomynow.com/2019/09/09/long-term-study-maps-relativistic-effects-in-binary-pulsar/

Quote
FAST latched on to FRB 121102 on August 30, before recording dozens of later pulses (on one particular day, September 3, more than 20 pulses were detected). So, this looks like a particularly persistent FRB.

The 19-beam receiver on FAST is especially sensitive to radio signals, covering the 1.05-1.45 GHz frequency range, and that makes it perfect for keeping an eye on FRB 121102.

https://www.sciencealert.com/that-giant-radio-telescope-in-china-has-now-detected-a-repeating-frb
Title: Re: Astronomy & Planetary Science Thread
Post by: RotoSequence on 09/11/2019 06:04 am
Interstellar Interloper 2: Comet Boogaloo?

https://twitter.com/Yeqzids/status/1171491786121891843

https://twitter.com/Yeqzids/status/1171492152053944320

https://cneos.jpl.nasa.gov/scout/#/object/gb00234
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 09/11/2019 03:33 pm
Interstellar Interloper 2: Comet Boogaloo?

Maybe. It's a relatively big fuzzy blob ... so a few weeks patience is needed.

The eccentricity e = ~2.9 is very hyperbolic so maybe

--- Tony
Title: Re: Astronomy & Planetary Science Thread
Post by: scienceguy on 09/11/2019 06:44 pm
Hubble finds water vapor at an exoplanet

https://www.nasa.gov/feature/goddard/2019/nasa-s-hubble-finds-water-vapor-on-habitable-zone-exoplanet-for-1st-time

The planet is 110 light years away
Title: Re: Astronomy & Planetary Science Thread
Post by: hop on 09/11/2019 10:01 pm
The eccentricity e = ~2.9 is very hyperbolic so maybe
--- Tony
MPEC is now out, officially C/2019 Q4 (Borisov), with e = ~3 https://minorplanetcenter.net/mpec/K19/K19RA6.html
JPL puts it at ~3.5 +/-2  https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=C%2F2019%20Q4;old=0;orb=1;cov=0;log=0;cad=0#elem

Not officially confirmed as interstellar, but certainly leaning that way.

Maybe this belongs in the hyperbolic hyperbole (https://forum.nasaspaceflight.com/index.php?topic=44075.420) thread.

Edit:
Commentary initially missing from the web version of the MPEC
Quote
This object was reported as a comet candidate by G. Borisov (L51) on Aug. 30 UTC.  After posting on the NEOCP/PCCP, confirmation of the cometary nature was provided by numerous observers.  Selected reports are as follows:

OC  Date     Observer(s)     Coma              Tail                 Exp.
L51 20190830 G. Borisov       7", condensed           
L51 20190901 G. Borisov       7", condensed    15", P.A. 300-320     9 x 120s
H06 20190901 H. Sato         12", condensed                         10 x  60s
J95 20190902 P. Birtwhistle  12", diffuse      Poss. elongation in P.A. 300
N55 20190906 T. Chen et al.   4", mod. cond.   Elongation in P.A. 330/140
850 20190908 D. T. Durig     23", diffuse      24", P.A. 240-300   150 x  10s
J95 20190908 P. Birtwhistle  14", condensed    Extended in P.A. 295
121 20190908 I. Slyusarev    10", condensed    50" in P.A. 310
568 20190908 K. Meech         5", condensed    40" in P.A. 315
 
Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements shown below, which would indicate an interstellar origin.  A number of other orbit computers have reached similar conclusions, initially D. Farnocchia (JPL), W. Gray, and D. Tholen (UoH). Further observations are clearly very desirable, as all currently-available observations have been obtained at small solar elongations and low elevations. Absent an unexpected fading or disintegration, this object should be observable for at least a year.
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 09/12/2019 06:27 pm
Once confirmed, I think it should have a thread of its own ... a very different beast to 'Oumuamua

--- Tony
Title: Re: Astronomy & Planetary Science Thread
Post by: lamid on 09/13/2019 11:07 pm
all about C/2019 Q4
https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov)
Title: Re: Astronomy & Planetary Science Thread
Post by: Zed_Noir on 09/14/2019 01:17 am
all about C/2019 Q4
https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov)

Broken link. Missing ")" symbol at the end of the link address string.
https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov) (https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov))



Wonder if it is possible to fly some camera packages to get some images of the object before it flys away from the Solar system?
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 09/14/2019 06:19 am
all about C/2019 Q4
https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov)

Broken link. Missing ")" symbol at the end of the link address string.
https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov) (https://en.wikipedia.org/wiki/C/2019_Q4_(Borisov))



Wonder if it is possible to fly some camera packages to get some images of the object before it flys away from the Solar system?

No, the comet passes perihelion (which is outside Mars' orbit) already in December. It will be far gone before any probe could be even launched.
Title: Re: Astronomy & Planetary Science Thread
Post by: hop on 09/14/2019 05:26 pm
No, the comet passes perihelion (which is outside Mars' orbit) already in December. It will be far gone before any probe could be even launched.
Yeah, no chance of visiting this one. However, the ESA Comet Interceptor mission (https://www.esa.int/Our_Activities/Space_Science/ESA_s_new_mission_to_intercept_a_comet) will have to potential to target an object like this after it launches.

Bolun started a new thread for 2019 Q4 discussion: https://forum.nasaspaceflight.com/index.php?topic=49027.0 (well justified, there's very little chance it will be anything but interstellar at this point)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/16/2019 07:42 pm
https://www.syfy.com/syfywire/remember-tabbys-star-it-may-have-a-friend-and-maybe-lots-of-them
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/18/2019 08:56 pm
Quote
About 466 million years ago, a massive, 93-mile-wide asteroid disintegrated somewhere between Jupiter and Mars, sending waves of dust that shrouded the Earth. New research in the journal Science Advances suggests that this asteroid collision in outer space may have triggered an ice age down here on Earth, leading to a huge increase in the number and diversity of living things in the ancient oceans.

The study, published on Wednesday, presents evidence that the fragmented asteroid’s dust filled the inner solar system to the point that it shaded the Earth from the sun’s radiation. As the planet got cooler, ice began to build up at higher altitudes near the northern and southern poles, causing sea levels to fall.

https://www.inverse.com/article/59368-asteroid-collision-may-have-triggered-ice-age

Here’s the related paper:

https://advances.sciencemag.org/content/5/9/eaax4184
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/24/2019 06:35 am
Quote
Venus may have been a temperate planet hosting liquid water for 2-3 billion years, until a dramatic transformation starting over 700 million years ago resurfaced around 80% of the planet. A study presented today at the EPSC-DPS Joint Meeting 2019 by Michael Way of The Goddard Institute for Space Science gives a new view of Venus’s climatic history and may have implications for the habitability of exoplanets in similar orbits.

Quote
“We need more missions to study Venus and get a more detailed understanding of its history and evolution,” said Way. “However, our models show that there is a real possibility that Venus could have been habitable and radically different from the Venus we see today. This opens up all kinds of implications for exoplanets found in what is called the ‘Venus Zone’, which may in fact host liquid water and temperate climates.”

https://www.europlanet-society.org/could-venus-have-been-habitable/

Here’s the related study:

https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1846-1.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/24/2019 06:49 am
Quote
NGC 3147, as imaged by the Hubble Space Telescope, is a beautiful face-on spiral galaxy 130 million light years away in the constellation Draco that features a multitude of young blue stars, vast nebulas and silhouetted dust lanes with sweeping, well-defined spiral arms. It’s also home to a supermassive black hole some 250 million times more massive than the Sun that is surrounded by a compact disc made up of stars and dust trapped in the hole’s gravitational grip.

https://astronomynow.com/2019/09/05/hubble-studies-home-galaxy-of-monster-black-hole/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/26/2019 09:07 pm
Quote
A distant blast of radio energy from one galaxy pierced the diffuse, gaseous halo around another, letting astronomers probe two cosmic oddities at once.

The brief, bright flare of a fast radio burst, or FRB, originated in a dim and distant galaxy, according to observations with a telescope array in the Australian outback (SN: 6/27/19). And by coincidence, the radio waves passed through another galaxy to reach Earth.

https://www.sciencenews.org/article/fast-radio-burst-shined-light-galaxy-mysterious-gas-halo

https://youtu.be/emXJt6khFO0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/29/2019 11:46 am
Quote
Astronomers have discovered a gigantic planet orbiting a puny star some 30 light-years away. And according to current theories, the planet shouldn’t exist. Dubbed GJ 3512 b, the gas giant is at least half the mass of Jupiter. But it orbits a red dwarf star that’s just one-tenth the mass of our Sun.

"Around such stars there should only be planets the size of the Earth or somewhat more massive Super-Earths," said Christoph Mordasini of the University of Bern in a press release. "GJ 3512 b, however, is … at least one order of magnitude more massive than the planets predicted by theoretical models for such small stars."

https://astronomy.com/news/2019/09/giant-planet-found-around-tiny-star-defies-expectations
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/02/2019 04:53 pm
Quote
The planet’s magnetic poles swapped places at an astounding rate about 500 million years ago, which offers clues to core formation and hints at the effects on early life.

Quote
“We did not expect such a high reversal frequency,” Gallet writes in an email, emphasizing that at that time, anything exceeding four or five reversals was considered high. The fast rate left him and his colleagues with a nagging suspicion that they needed to collect more samples. In the summer of 2016, they returned to do just that, cutting some 550 small blocks of rock every four to eight inches. Analysis of the magnetic signatures confirmed their suspicion: Over the three million years captured in their samples, they detected a striking 78 field reversals.

https://www.nationalgeographic.com/science/2019/10/earths-magnetic-field-flipped-more-times-scientists-thought/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/05/2019 10:42 am
Quote
Astronomers have discovered what our neighbour galaxy Andromeda last had for lunch. Like the Milky Way, Andromeda has been snacking on dwarf galaxies for billions of years. Now recent observations, taken by several telescopes on Mauna Kea in Hawaii, have exposed the stellar left-overs of the galaxy’s previous meals.

https://www.skyatnightmagazine.com/news/andromeda-galaxys-last-meal/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/08/2019 02:11 pm
Quote
Saturn has taken over from Jupiter as host to the most moons in the solar system after astronomers spotted 20 more lumps of rock orbiting the ringed planet.
It brings the number of Saturnian moons to 82, surpassing the 79 that are known to orbit Jupiter, its larger, inner neighbour.
“It’s exciting to find them,” said Scott Sheppard, an astronomer who led the work at the Carnegie Institution for Science in Washington DC. “These moons are very far away from the planet.” Each is about three miles across.

https://www.google.co.uk/amp/s/amp.theguardian.com/science/2019/oct/07/saturn-overtakes-jupiter-as-host-to-most-moons-in-solar-system
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/10/2019 07:54 pm
Quote
Our large galaxy, the Milky Way, is orbited by more than 50 other, smaller galaxies. But astronomers recently discovered that some of these galaxies were kidnapped from neighboring large dwarf galaxy the Large Magellanic Cloud.
The Large Magellanic Cloud, so called because it appears like a faint cloud, is also on a collision course with our galaxy.
The LMC is fairly new to orbiting the Milky Way, entering our corner of the universe 1.5 billion years ago. It's now the brightest satellite galaxy we have, 163,000 light-years from the Milky Way. Previously, astronomers thought it would hang out in a quiet, long orbit or speed away from the gravity of the Milky Way and move on.

https://edition-m.cnn.com/2019/10/10/world/milky-way-kidnap-dwarf-galaxies-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/13/2019 07:17 pm
Quote
A new study of the Ovda Fluctus lava flow on Venus indicates that it is made of basaltic lava. This discovery weakens the notion that Venus might once have been Earth-like with an ancient ocean of liquid water.

https://newsroom.usra.edu/was-venus-once-warm-and-wet-new-study-of-lava-flow-suggests-not/
Title: Re: Astronomy & Planetary Science Thread
Post by: bolun on 10/14/2019 12:07 pm
http://www.esa.int/Science_Exploration/Space_Science/Exoplanet_and_cosmology_discoveries_awarded_Nobel_Prize_in_Physics

Quote
Exoplanet and cosmology discoveries awarded Nobel Prize in Physics

ESA congratulates 2019 Nobel Prize in Physics laureates Michel Mayor and Didier Queloz, who have been awarded the prestigious prize for the first discovery of an exoplanet orbiting a solar-type star, and James Peebles, honoured for the theoretical framework of cosmology used to investigate the Universe on its largest scales.

The two halves of this year’s award recognise groundbreaking contributions to our understanding of how the Universe formed and evolved, as well as the role of Earth – and of us, as humans – in the overall cosmic picture.
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 10/15/2019 05:44 am
Four newborn planets transiting the young solar analog V1298 Tau (https://arxiv.org/abs/1910.04563) (arXiv)

Quote
(Abstract)
Exoplanets orbiting pre-main sequence stars are laboratories for studying planet evolution processes, including atmospheric loss, orbital migration, and radiative cooling. V1298 Tau, a young solar analog with an age of 23 ± 4 Myr, is one such laboratory. The star is already known to host a Jupiter-sized planet on a 24 day orbit. Here, we report the discovery of three additional planets --- all between the size of Neptune and Saturn --- based on our analysis of K2 Campaign 4 photometry. Planets c and d have sizes of 5.6 and 6.4 R⊕, respectively and with orbital periods of 8.25 and 12.40 days reside 0.25% outside of the nominal 3:2 mean-motion resonance. Planet e is 8.7 R⊕ in size but only transited once in the K2 time series and thus has a period longer than 36 days, but likely shorter than 223 days. The V1298 Tau system may be a precursor to the compact multiplanet systems found to be common by the Kepler mission. However, the large planet sizes stand in sharp contrast to the vast majority of Kepler multis which have planets smaller than 3 R⊕. Simple dynamical arguments suggest total masses of <28 M⊕ and <120 M⊕ for the c-d and d-b planet pairs, respectively. The implied low masses suggest that the planets may still be radiatively cooling and contracting, and perhaps losing atmosphere. The V1298 Tau system offers rich prospects for further follow-up including atmospheric characterization by transmission or eclipse spectroscopy, dynamical characterization through transit-timing variations, and measurements of planet masses and obliquities by radial velocities.
Quote
(Conclusion 4)
The V1298 Tau planetary system constitutes a valuable laboratory for testing photo-evaporation models across a range of incident flux and at a stage when atmospheric loss is expected to be particularly vigorous. Photo-evaporation is expected to play an important role in the evolution of the inner two planets, which may be actively losing atmosphere, but a much lesser role for the outer two planets ...
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 10/15/2019 06:03 am
Two major accretion epochs in M31 from two distinct populations of globular clusters (https://www.nature.com/articles/s41586-019-1597-1) (nature, full paper behind paywall)

Quote
(Abstract)
Large galaxies grow through the accumulation of dwarf galaxies. In principle it is possible to trace this growth history via the properties of a galaxy’s stellar halo. Previous investigations of the galaxy Messier 31 (M31, Andromeda) have shown that outside a galactocentric radius of 25 kiloparsecs the population of halo globular clusters is rotating in alignment with the stellar disk, as are more centrally located clusters. The M31 halo also contains coherent stellar substructures, along with a smoothly distributed stellar component. Many of the globular clusters outside a radius of 25 kiloparsecs are associated with the most prominent substructures, but some are part of the smooth halo. Here we report an analysis of the kinematics of these globular clusters. We find two distinct populations rotating perpendicular to each other. The rotation axis for the population associated with the smooth halo is aligned with the rotation axis for the plane of dwarf galaxies that encircles M31. We interpret these separate cluster populations as arising from two major accretion epochs, probably separated by billions of years. Stellar substructures from the first epoch are gone, but those from the more recent second epoch still remain.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 10/18/2019 08:55 pm
Quote
Astronomers have captured high-speed camera views of crackling millisecond flashes of light generated by debris being pulled into a relatively nearby black hole, violent flicker-like bursts of radiation equivalent to the energy of a hundred suns released “in the blink of an eye.”

The HiPERCAM instrument on the Gran Telescopio Canarias at La Palma in the Canary Islands and the X-ray-sensitive NICER instrument aboard the International Space Station gave an international team of astronomers led by the University of Southhampton a bird’s eye view of a black hole system known as MAXI J1820+070.

https://www.youtube.com/watch?v=9V-sjuOzVVA

https://astronomynow.com/2019/10/13/best-view-yet-of-flickering-jets-in-black-hole-feeding-frenzy/

Quote
The universe bathes in a sea of light, from the blue-white flickering of young stars to the deep red glow of hydrogen clouds. Beyond the colors seen by human eyes, there are flashes of x-rays and gamma rays, powerful bursts of radio, and the faint, ever-present glow of the cosmic microwave background. The cosmos is filled with colors seen and unseen, ancient and new. But of all these, there was one color that appeared before all the others, the first color of the universe.

https://www.universetoday.com/143769/what-was-the-first-color-in-the-universe/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/20/2019 06:38 am
This article is as much about the problems with working out the age of the universe as it is refining the age of this star.

Quote
For more than 100 years, astronomers have been observing a curious star located some 190 light years away from Earth in the constellation Libra. It rapidly journeys across the sky at 800,000 mph (1.3 million kilometers per hour). But more interesting than that, HD 140283 — or Methuselah as it's commonly known — is also one of the universe's oldest known stars.

https://www.space.com/how-can-a-star-be-older-than-the-universe.html

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/23/2019 08:16 pm
Quote
So how might we derive surface maps of Earth-like planets from analysing these varying ‘multi-wavelength single-point light curves’ – could we watch their configuration of continents and oceans spinning under our telescopes?

Graduate student Siteng Fan and his colleagues at Caltech and JPL in Pasadena have been working on techniques for exactly this – by using degraded observations of Earth as a proxy for a habitable exoplanet and trying to reconstruct the global map.

https://www.skyatnightmagazine.com/space-science/possible-make-map-of-exoplanet/

Here’s the related paper:

https://arxiv.org/abs/1908.04350
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/24/2019 03:56 pm
Three Red Suns in the Sky: A Transiting, Terrestrial Planet in a Triple M-dwarf System at 6.9 pc

We present the discovery from Transiting Exoplanet Survey Satellite (TESS) data of LTT 1445Ab. At a distance of 6.9 pc, it is the second nearest transiting exoplanet system found to date, and the closest one known for which the primary is an M dwarf. The host stellar system consists of three mid-to-late M dwarfs in a hierarchical configuration, which are blended in one TESS pixel. We use MEarth data and results from the Science Processing Operations Center data validation report to determine that the planet transits the primary star in the system. The planet has a radius of ${1.38}_{-0.12}^{+0.13}$ ${R}_{\oplus }$, an orbital period of ${5.35882}_{-0.00031}^{+0.00030}$ days, and an equilibrium temperature of ${433}_{-27}^{+28}$ K. With radial velocities from the High Accuracy Radial Velocity Planet Searcher, we place a 3σ upper mass limit of 8.4 ${M}_{\oplus }$ on the planet. LTT 1445Ab provides one of the best opportunities to date for the spectroscopic study of the atmosphere of a terrestrial world. We also present a detailed characterization of the host stellar system. We use high-resolution spectroscopy and imaging to rule out the presence of any other close stellar or brown dwarf companions. Nineteen years of photometric monitoring of A and BC indicate a moderate amount of variability, in agreement with that observed in the TESS light-curve data. We derive a preliminary astrometric orbit for the BC pair that reveals an edge-on and eccentric configuration. The presence of a transiting planet in this system hints that the entire system may be co-planar, implying that the system may have formed from the early fragmentation of an individual protostellar core.

https://iopscience.iop.org/article/10.3847/1538-3881/ab364d
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/28/2019 03:45 pm
Quote
Astronomers using ESO's SPHERE instrument at the Very Large Telescope (VLT) have revealed that the asteroid Hygiea could be classified as a dwarf planet. The object is the fourth largest in the asteroid belt after Ceres, Vesta and Pallas. For the first time, astronomers have observed Hygiea in sufficiently high resolution to study its surface and determine its shape and size. They found that Hygiea is spherical, potentially taking the crown from Ceres as the smallest dwarf planet in the Solar System.

https://www.eurekalert.org/pub_releases/2019-10/e-etr102519.php

https://youtu.be/VBi-KeZABl4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/29/2019 03:26 pm
Quote
The snapshot reveals what looks like an uncanny pair of glowing eyes glaring menacingly in our direction. The piercing "eyes" are the most prominent feature of what resembles the face of an otherworldly creature. This frightening object is actually the result of a titanic head-on collision between two galaxies.

https://hubblesite.org/contents/news-releases/2019/news-2019-51
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/01/2019 07:33 pm
Quote
Black holes are an important part of how astrophysicists make sense of the universe – so important that scientists have been trying to build a census of all the black holes in the Milky Way galaxy.

But new research shows that their search might have been missing an entire class of black holes that they didn’t know existed.

In a study published today in the journal Science, astronomers offer a new way to search for black holes, and show that it is possible there is a class of black holes smaller than the smallest known black holes in the universe.

https://news.osu.edu/scientists-may-just-have-discovered-a-new-class-of-black-holes/

More here:

https://www.technologyreview.com/f/614664/scientists-have-spotted-a-tiny-black-hole-that-may-be-just-12-miles-across/
Title: Astronomy & Planetary Science Thread
Post by: Star One on 11/10/2019 07:01 pm
A NICER Thermonuclear Burst from the Millisecond X-Ray Pulsar SAX J1808.4–3658

The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the 2019 August outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4–3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of (2.3 ± 0.1) × 10−7 erg s−1 cm−2, this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at 1.0 and 6.7 keV, and burst oscillations at the known pulsar spin frequency, with ≈4% fractional sinusoidal amplitude. We interpret the burst flux evolution as the detection of the local Eddington limits associated with the hydrogen and helium layers of the neutron star envelope. The emission lines are likely associated with Fe, due to reprocessing of the burst emission in the accretion disk.

https://iopscience.iop.org/article/10.3847/2041-8213/ab4ae1

NASA's NICER Catches Record-setting X-ray Burst

NASA’s Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station detected a sudden spike of X-rays at about 10:04 p.m. EDT on Aug. 20. The burst was caused by a massive thermonuclear flash on the surface of a pulsar, the crushed remains of a star that long ago exploded as a supernova.

The X-ray burst, the brightest seen by NICER so far, came from an object named SAX J1808.4-3658, or J1808 for short. The observations reveal many phenomena that have never been seen together in a single burst. In addition, the subsiding fireball briefly brightened again for reasons astronomers cannot yet explain.

“This burst was outstanding,” said lead researcher Peter Bult, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park. “We see a two-step change in brightness, which we think is caused by the ejection of separate layers from the pulsar surface, and other features that will help us decode the physics of these powerful events.”

The explosion, which astronomers classify as a Type I X-ray burst, released as much energy in 20 seconds as the Sun does in nearly 10 days. The detail NICER captured on this record-setting eruption will help astronomers fine-tune their understanding of the physical processes driving the thermonuclear flare-ups of it and other bursting pulsars.

https://youtu.be/1FkoWncpMYg

A pulsar is a kind of neutron star, the compact core left behind when a massive star runs out of fuel, collapses under its own weight, and explodes. Pulsars can spin rapidly and host X-ray-emitting hot spots at their magnetic poles. As the object spins, it sweeps the hot spots across our line of sight, producing regular pulses of high-energy radiation.

J1808 is located about 11,000 light-years away in the constellation Sagittarius. It spins at a dizzying 401 rotations each second, and is one member of a binary system. Its companion is a brown dwarf, an object larger than a giant planet yet too small to be a star. A steady stream of hydrogen gas flows from the companion toward the neutron star, and it accumulates in a vast storage structure called an accretion disk.

Gas in accretion disks doesn’t move inward easily. But every few years, the disks around pulsars like J1808 become so dense that a large amount of the gas becomes ionized, or stripped of its electrons. This makes it more difficult for light to move through the disk. The trapped energy starts a runaway process of heating and ionization that traps yet more energy. The gas becomes more resistant to flow and starts spiraling inward, ultimately falling onto the pulsar.

Hydrogen raining onto the surface forms a hot, ever-deepening global “sea.” At the base of this layer, temperatures and pressures increase until hydrogen nuclei fuse to form helium nuclei, which produces energy — a process at work in the core of our Sun.     

“The helium settles out and builds up a layer of its own,” said Goddard’s Zaven Arzoumanian, the deputy principal investigator for NICER and a co-author of the paper. “Once the helium layer is a few meters deep, the conditions allow helium nuclei to fuse into carbon. Then the helium erupts explosively and unleashes a thermonuclear fireball across the entire pulsar surface.”

Astronomers employ a concept called the Eddington limit — named for English astrophysicist Sir Arthur Eddington — to describe the maximum radiation intensity a star can have before that radiation causes the star to expand. This point depends strongly on the composition of the material lying above the emission source. 

“Our study exploits this longstanding concept in a new way,” said co-author Deepto Chakrabarty, a professor of physics at the Massachusetts Institute of Technology in Cambridge. “We are apparently seeing the Eddington limit for two different compositions in the same X-ray burst. This is a very powerful and direct way of following the nuclear burning reactions that underlie the event.”

As the burst started, NICER data show that its X-ray brightness leveled off for almost a second before increasing again at a slower pace. The researchers interpret this “stall” as the moment when the energy of the blast built up enough to blow the pulsar’s hydrogen layer into space.

The fireball continued to build for another two seconds and then reached its peak, blowing off the more massive helium layer. The helium expanded faster, overtook the hydrogen layer before it could dissipate, and then slowed, stopped and settled back down onto the pulsar’s surface. Following this phase, the pulsar briefly brightened again by roughly 20 percent for reasons the team does not yet understand.

During J1808’s recent round of activity, NICER detected another, much fainter X-ray burst that displayed none of the key features observed in the Aug. 20 event.

In addition to detecting the expansion of different layers, NICER observations of the blast reveal X-rays reflecting off of the accretion disk and record the flickering of “burst oscillations” — X-ray signals that rise and fall at the pulsar’s spin frequency but that occur at different surface locations than the hot spots responsible for its normal X-ray pulses.

A paper describing the findings has been published by The Astrophysical Journal Letters and is available online.

NICER is an Astrophysics Mission of Opportunity within NASA's Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA's Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.

https://www.nasa.gov/feature/goddard/2019/nasas-nicer-catches-record-setting-x-ray-burst
Title: Astronomy & Planetary Science Thread
Post by: Star One on 11/11/2019 06:35 am
I am sure I’ve heard this theory before in relation to explain the mechanism of an expanding universe. That the universe is like a balloon with the galaxies being dots on the skin of the balloon, and expansion is caused by some force filling the balloon and moving the dots further and further apart on the skin as a result. As the results come from the Planck mission they are giving support to a new CMB mission called CORE. Anyone got any info on this mission?

Quote
Scientists think the universe is flat, but new observations suggest that we might actually be living in a gigantic sphere.

https://www.vice.com/amp/en_in/article/ywajej/there-might-be-a-hidden-crisis-in-what-we-know-about-the-universe

Here’s the related paper:

https://www.nature.com/articles/s41550-019-0906-9.epdf
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 11/11/2019 06:06 pm
I am sure I’ve heard this theory before in relation to explain the mechanism of an expanding universe. That the universe is like a balloon with the galaxies being dots on the skin of the balloon, and expansion is caused by some force filling the balloon and moving the dots further and further apart on the skin as a result. As the results come from the Planck mission they are giving support to a new CMB mission called CORE. Anyone got any info on this mission?

Some version of CORE was proposed for Cosmic Vision M3 (IIRC, not quite sure about this), M4 and M5 slots, but it has never made the final downselection shortlist. At least the latest one didn't even make it through the cost/technical preliminary screening.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/11/2019 07:23 pm
I am sure I’ve heard this theory before in relation to explain the mechanism of an expanding universe. That the universe is like a balloon with the galaxies being dots on the skin of the balloon, and expansion is caused by some force filling the balloon and moving the dots further and further apart on the skin as a result. As the results come from the Planck mission they are giving support to a new CMB mission called CORE. Anyone got any info on this mission?

Some version of CORE was proposed for Cosmic Vision M3 (IIRC, not quite sure about this), M4 and M5 slots, but it has never made the final downselection shortlist. At least the latest one didn't even make it through the cost/technical preliminary screening.

Thanks. I suppose those who pick think that yet another CMB mission is not justified at this stage.
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 11/11/2019 07:30 pm
Thanks. I suppose those who pick think that yet another CMB mission is not justified at this stage.

Actually, a few months ago JAXA selected a CMB mission (LiteBIRD) as its next 'large' mission. I'm not sure when exactly it's planned to launch, but probably in the late(ish) 2020s.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2019 06:21 am
Thanks. I suppose those who pick think that yet another CMB mission is not justified at this stage.

Actually, a few months ago JAXA selected a CMB mission (LiteBIRD) as its next 'large' mission. I'm not sure when exactly it's planned to launch, but probably in the late(ish) 2020s.

Would that be useful to the above paper, is it a CORE equivalent mission?
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 11/12/2019 06:47 pm
Would that be useful to the above paper, is it a CORE equivalent mission?

LiteBIRD has the same main science goal as CORE, detecting the CMB polarisation and I believe the design sensitivities are similar (though there are differences, CORE would seem to have better angular resolution, for example). But it seems to me that neither is really targeting the question that the paper discusses and I'm not sure how much either mission would be able to say about that.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/13/2019 06:27 am
Would that be useful to the above paper, is it a CORE equivalent mission?

LiteBIRD has the same main science goal as CORE, detecting the CMB polarisation and I believe the design sensitivities are similar (though there are differences, CORE would seem to have better angular resolution, for example). But it seems to me that neither is really targeting the question that the paper discusses and I'm not sure how much either mission would be able to say about that.

Thanks. I am guessing that the article was just editorialising by adding the CORE mission to the discussion.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/13/2019 03:10 pm
Discovery of a nearby 1700 km/s star ejected from the Milky Way by Sgr A*

We present the serendipitous discovery of the fastest Main Sequence hyper-velocity star (HVS) by the Southern Stellar Stream Spectroscopic Survey (S5). The star S5-HVS1 is a ∼2.35 M⊙ A-type star located at a distance of ∼9 kpc from the Sun and has a heliocentric radial velocity of 1017 ± 2.7  km s−1 without any signature of velocity variability. The current 3-D velocity of the star in the Galactic frame is 1755 ± 50  km s−1. When integrated backwards in time, the orbit of the star points unambiguously to the Galactic Centre, implying that S5-HVS1 was kicked away from Sgr A* with a velocity of ∼1800  km s−1 and travelled for 4.8 Myr to its current location. This is so far the only HVS confidently associated with the Galactic Centre. S5-HVS1 is also the first hyper-velocity star to provide constraints on the geometry and kinematics of the Galaxy, such as the Solar motion Vy, ⊙ = 246.1 ± 5.3  km s−1 or position R0 = 8.12 ± 0.23 kpc. The ejection trajectory and transit time of S5-HVS1 coincide with the orbital plane and age of the annular disk of young stars at the Galactic centre, and thus may be linked to its formation. With the S5-HVS1 ejection velocity being almost twice the velocity of other hyper-velocity stars previously associated with the Galactic Centre, we question whether they have been generated by the same mechanism or whether the ejection velocity distribution has been constant over time.

https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stz3081/5612212
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/14/2019 09:12 pm
Neptune Moon Dance:

https://www.youtube.com/watch?v=WEsiSZtIDyI

Are Wormholes Real?

https://www.youtube.com/watch?v=FN7cLhd1ycY

If you could see every satellite, what would the  sky look like?

https://www.youtube.com/watch?v=dJNGi-bt9NM
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/18/2019 06:31 am
Quote
James Peebles won this year's Nobel prize in physics for helping transform the field of cosmology into a respected science, but if there's one term he hates to hear, it's "Big Bang Theory."

The leading explanation for the universe in its earliest periods has held sway for decades, with Peebles' early work investigating cosmic background radiation helping to cement many of the details.

https://www.afp.com/en/news/826/top-cosmologists-lonely-battle-against-big-bang-theory-doc-1m915e1
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/19/2019 07:28 am
A measurement of water vapour amid a largely quiescent environment on Europa

Previous investigations proved the existence of local density enhancements in Europa’s atmosphere, advancing the idea of a possible origination from water plumes. These measurement strategies, however, were sensitive either to total absorption or atomic emissions, which limited the ability to assess the water content. Here we present direct searches for water vapour on Europa spanning dates from February 2016 to May 2017 with the Keck Observatory. Our global survey at infrared wavelengths resulted in non-detections on 16 out of 17 dates, with upper limits below the water abundances inferred from previous estimates. On one date (26 April 2016) we measured 2,095 ± 658 tonnes of water vapour at Europa’s leading hemisphere. We suggest that the outgassing of water vapour on Europa occurs at lower levels than previously estimated, with only rare localized events of stronger activity.

https://www.nature.com/articles/s41550-019-0933-6

Accompanying NASA press release:

https://www.nasa.gov/feature/goddard/2019/nasa-scientists-confirm-water-vapor-on-europa
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/20/2019 06:43 am
Discovering Earth’s transient moons with the Large Synoptic Survey Telescope

Earth’s temporarily-captured orbiters (TCOs) are a sub-population of near-Earth objects (NEOs). TCOs can provide constraints for NEO population models in the 1–10-metre-diameter range, and they are outstanding targets for in situ exploration of asteroids due to a low requirement on
. So far there has only been a single serendipitous discovery of a TCO. Here we assess in detail the possibility of their discovery with the upcoming Large Synoptic Survey Telescope (LSST), previously identified as the primary facility for such discoveries. We simulated observations of TCOs by combining a synthetic TCO population with an LSST survey simulation. We then assessed the detection rates, detection linking and orbit computation, and sources for confusion. Typical velocities of detectable TCOs will range from 1
/day to 50
/day, and typical apparent
 magnitudes from 21 to 23. Potentially-hazardous asteroids have observational characteristics similar to TCOs, but the two populations can be distinguished based on their orbits with LSST data alone. We predict that a TCO can be discovered once every year with the baseline moving-object processing system (MOPS). The rate can be increased to one TCO discovery every two months if tools complementary to the baseline MOPS are developed for the specific purpose of discovering these objects.

https://www.sciencedirect.com/science/article/pii/S0019103519304117#!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/20/2019 06:54 am
Many open clusters listed in modern catalogues were initially reported by visual astronomers as apparent overdensities of bright stars. As observational techniques and analysis methods continue to improve, some of them have been shown to be chance alignments of stars and not true clusters. Recent publications have provided membership lists for over a thousand clusters, however, many nearby objects listed in the literature have so far evaded detection. We aim to update the Gaia DR2 cluster census by performing membership determinations for known clusters that had been missed by previous studies and for recently-discovered clusters. We investigate a sub-set of non-detected clusters that, according to their literature parameters, should be easily visible in Gaia. Confirming or disproving the existence of old, inner-disc, high-altitude clusters is especially important as their survival or disruption is linked to the dynamical processes that drive the evolution of the Milky Way. We employed the Gaia DR2 catalogue and a membership assignment procedure, as well as visual inspections of spatial, proper motion, and parallax distributions. We used membership lists provided by other authors when available. We derived membership lists for 150 objects, including ten that were already known prior to Gaia. We compiled a final list of members for 1481 clusters. Among the objects that we are still unable to identify with the Gaia data, we argue that many (mostly putatively old, relatively nearby, high-altitude objects) are not true clusters. At present, the only confirmed cluster located further than 500pc away from the Galactic plane within the Solar circle is NGC 6791. It is likely that the objects discussed in this study only represent a fraction of the non-physical groupings erroneously listed in the catalogues as genuine open clusters and that those lists need further cleaning.

http://adsabs.net/abs/2019arXiv191107075C
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/20/2019 08:08 pm
Quote
Is our fundamental reality continuous or is it chopped up into tiny, discrete bits?

Asked another way, is space-time smooth or chunky? The question cuts to the heart of the most fundamental theories of physics, linking together the way space and time intersect with the material of our everyday existence.

However, experimentally testing the nature of space and time has been impossible, because of the extreme energies needed to probe such tiny scales in the universe. That is — until now. A team of astronomers has proposed an ambitious new plan to use a fleet of tiny spacecraft to detect subtle changes in the speed of light, a hallmark of some of the most mind-bending theories of the cosmos. If space and time are indeed broken up into little bits, the research could pave the way for a completely new understanding of reality.

https://www.livescience.com/is-space-time-smooth-chunky.html
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/22/2019 06:49 am
Quote
Research team discovers three supermassive black holes at the core of one galaxy

https://www.uni-goettingen.de/en/3240.html?id=5719

Quote
The leftovers from a spectacular supernova that revolutionised our understanding of how stars end their lives have finally been spotted by astronomers at Cardiff University.

The scientists claim to have found evidence of the location of a neutron star that was left behind when a massive star ended its life in a gigantic explosion, leading to a famous supernova dubbed Supernova 1987A.

For more than 30 years astronomers have been unable to locate the neutron star - the collapsed leftover core of the giant star - as it has been concealed by a thick cloud of cosmic dust.

Using extremely sharp and sensitive images taken with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in the Atacama Desert of northern Chile, the team have found a particular patch of the dust cloud that is brighter than its surroundings, and which matches the suspected location of the neutron star.

https://www.eurekalert.org/pub_releases/2019-11/cu-sfe111919.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/24/2019 11:36 pm
Quote
Everything in our Universe is held together or pushed apart by four fundamental forces: gravity, electromagnetism, and two nuclear interactions. Physicists now think they've spotted the actions of a fifth physical force emerging from a helium atom.

https://www.sciencealert.com/physicists-claim-a-they-ve-found-even-more-evidence-of-a-new-force-of-nature

Related paper:

https://arxiv.org/abs/1910.10459
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 11/26/2019 04:01 pm
Quote
Everything in our Universe is held together or pushed apart by four fundamental forces: gravity, electromagnetism, and two nuclear interactions. Physicists now think they've spotted the actions of a fifth physical force emerging from a helium atom.

https://www.sciencealert.com/physicists-claim-a-they-ve-found-even-more-evidence-of-a-new-force-of-nature

Related paper:

https://arxiv.org/abs/1910.10459

The same group claimed the detection of a 17 MeV vector boson in a slightly different experiment a few years ago already.  Experts were skeptical then and I don't think it's going to be different this time.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/27/2019 06:53 am
Quote
Earlier this year, several amateur astronomers spotted an unusual anomaly on the planet Jupiter: bits of the gas giant's famed Great Red Spot appeared to be flaking off, raising fears that the planet's most identifiable feature might be showing signs of disappearing. But Philip Marcus, a physicist at the University of California, Berkeley, begs to differ. He argues that reports of the red spot's death have been greatly exaggerated, and at a meeting of the American Physical Society's Division of Fluid Dynamics in Seattle this week, he offered an intriguing counter-explanation for the flaking.

https://arstechnica.com/science/2019/11/no-jupiters-great-red-spot-is-not-disintegrating-physicist-claims/

Related paper:

http://meetings.aps.org/Meeting/DFD14/Session/M17.1

Quote
Researchers using the Murchison Widefield Array radio telescope have taken a new and significant step toward detecting a signal from the period in cosmic history when the first stars lit up the universe.

https://www.brown.edu/news/2019-11-26/reionization

Related paper:

https://arxiv.org/abs/1911.10216
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/28/2019 07:58 pm
Quote
Monterey Bay, just a few miles southeast of Santa Cruz, California, a never-before-seen cluster of faults has been found lurking on the ocean floor.
These newly spotted wrinkles in Earth’s crust, described in a paper published today in Science, are still largely a mystery. We can’t say much about their size, shape, or how active they are. Still, the findings show that even in one of the most seismically studied corners of the planet, fault maps of the ocean floor contain gaping holes. That’s a big problem, because if we don’t know where seafloor faults are, coastal communities are going to be in the dark about any earthquake or tsunami threats they might present.

https://www.nationalgeographic.com/science/2019/11/mysterious-tectonic-fault-zone-found-off-california-using-fiber-optics/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2019 06:31 am
Quote
Our Milky Way Galaxy is estimated to contain 100 million stellar black holes - cosmic bodies formed by the collapse of massive stars and so dense even light can't escape. Until now, scientists had estimated the mass of an individual stellar black hole in our Galaxy at no more than 20 times that of the Sun. But the discovery of a huge black hole by a Chinese-led team of international scientists has toppled that assumption.

The team, headed by Prof. LIU Jifeng of the National Astronomical Observatory of China of the Chinese Academy of Sciences (NAOC), spotted a stellar black hole with a mass 70 times greater than the Sun. The monster black hole is located 15 thousand light-years from Earth and has been named LB-1 by the researchers. The discovery is reported in the latest issue of Nature.

https://www.eurekalert.org/pub_releases/2019-11/caos-cao112519.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/03/2019 08:29 am
Astronomers Propose a Novel Method of Finding Atmospheres on Rocky Worlds

When NASA’s James Webb Space Telescope launches in 2021, one of its most anticipated contributions to astronomy will be the study of exoplanets—planets orbiting distant stars. Among the most pressing questions in exoplanet science is: Can a small, rocky exoplanet orbiting close to a red dwarf star hold onto an atmosphere?

In a series of four papers in the Astrophysical Journal, a team of astronomers proposes a new method of using Webb to determine whether a rocky exoplanet has an atmosphere. The technique, which involves measuring the planet’s temperature as it passes behind its star and then comes back into view, is significantly faster than more traditional methods of atmospheric detection like transmission spectroscopy.

“We find that Webb could easily infer the presence or absence of an atmosphere around a dozen known rocky exoplanets with less than 10 hours of observing time per planet,” said Jacob Bean of the University of Chicago, a co-author on three of the papers.

Astronomers are particularly interested in exoplanets orbiting red dwarf stars for a number of reasons. These stars, which are smaller and cooler than the Sun, are the most common type of star in our galaxy. Also, because a red dwarf is small, a planet passing in front of it will appear to block a larger fraction of the star's light than if the star were larger, like our Sun. This makes the planet orbiting a red dwarf easier to detect through this "transit" technique.

Red dwarfs also produce a lot less heat than our Sun, so to enjoy habitable temperatures, a planet would need to orbit quite close to a red dwarf star. In fact, to be in the habitable zone — the area around the star where liquid water could exist on a planet's surface — the planet has to orbit much closer to the star than Mercury is to the Sun. As a result, it will transit the star more frequently, making repeated observations easier.

But a planet orbiting so close to a red dwarf is subjected to harsh conditions. Young red dwarfs are very active, blasting out huge flares and plasma eruptions. The star also emits a strong wind of charged particles. All of these effects could potentially scour away a planet’s atmosphere, leaving behind a bare rock.

“Atmospheric loss is the number one existential threat to the habitability of planets,” said Bean.

Another key characteristic of exoplanets orbiting close to red dwarfs is central to the new technique: They are expected to be tidally locked, meaning they have a permanent dayside and nightside. As a result, we see different phases of the planet at different points in its orbit. When it crosses the face of the star, we see only the planet’s nightside. But when it is about to cross behind the star (an event known as a secondary eclipse), or is just emerging from behind the star, we can observe the dayside.

If a rocky exoplanet lacks an atmosphere, its dayside would be very hot, just as we see with the Moon or Mercury. However if a rocky exoplanet has an atmosphere, the presence of that atmosphere is expected to lower the dayside temperature that Webb would measure. It could do this in two ways. A thick atmosphere could transport heat from the dayside to the nightside through winds. A thinner atmosphere could still host clouds, which reflect a portion of the incoming starlight thereby lowering the temperature of the planet's dayside.

“Whenever you add an atmosphere, you’re going to lower the temperature of the dayside. So if we see something cooler than bare rock, we would infer it’s likely a sign of an atmosphere,” explained Daniel Koll of the Massachusetts Institute of Technology (MIT), the lead author on two of the papers.

Webb is ideally suited for making these measurements because it has a much larger mirror than other telescopes such as NASA's Hubble or Spitzer space telescopes, which allows it to collect more light, and it can target the appropriate infrared wavelengths.

The team’s calculations show that Webb should be able to detect the heat signature of a planet's atmosphere in one to two secondary eclipses – just a few hours of observing time. In contrast, detecting an atmosphere through spectroscopic observations would typically require eight or more transits for these same planets.

Transmission spectroscopy, which studies starlight filtered through the planet’s atmosphere, also suffers from interference due to clouds or hazes, which can mask the molecular signatures of the atmosphere. In that case the spectral plot, rather than showing pronounced absorption lines due to molecules, would be essentially flat.

“In transmission spectroscopy, if you get a flat line, it doesn’t tell you anything. The flat line could mean the universe is full of dead planets that don’t have an atmosphere, or that the universe is full of planets that have a whole range of diverse, interesting atmospheres, but they all look the same to us because they’re cloudy,” said Eliza Kempton of the University of Maryland, a co-author on three of the papers.

“Exoplanet atmospheres without clouds and hazes are like unicorns – we just haven’t seen them yet, and they may not exist at all,” she added.

The team emphasized that a cooler than expected dayside temperature would be an important clue, but it would not absolutely confirm an atmosphere exists. Any remaining doubts about the presence of an atmosphere can be ruled out with follow-up studies using other methods like transmission spectroscopy.

The new technique’s true strength will be in determining what fraction of rocky exoplanets likely have an atmosphere. Approximately a dozen exoplanets that are good candidates for this method were detected during the past year. More are likely to be found by the time Webb is operational.

“The Transiting Exoplanet Survey Satellite, or TESS, is finding piles of these planets,” stated Kempton.

The secondary eclipse method has one key limitation: it works best on planets that are too hot to be located in the habitable zone. However, determining whether or not these hot planets host atmospheres holds important implications for habitable-zone planets.

“If hot planets can hold onto an atmosphere, cooler ones should be able to at least as well,” said Koll.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

By Christine Pulliam / Laura Betz
Space Telescope Science Institute, Baltimore, Md./NASA Goddard
[email protected] / [email protected]
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/03/2019 08:40 am
Quote
Astronomers from CSIRO and Curtin University have used pulsars to probe the Milky Way's magnetic field. Working with colleagues in Europe, Canada, and South Africa, they have published the most precise catalogue of measurements towards mapping our Galaxy's magnetic field in 3-D.

https://phys.org/news/2019-11-galaxy-magnetic-field.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/03/2019 03:32 pm
Quote
How did life survive the most severe ice age? A McGill University-led research team has found the first direct evidence that glacial meltwater provided a crucial lifeline to eukaryotes during Snowball Earth, when the oceans were cut off from life-giving oxygen, answering a question puzzling scientists for years.

https://www.mcgill.ca/newsroom/channels/news/mcgill-led-research-unravels-mystery-how-early-animals-survived-ice-age-303012
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/04/2019 06:27 am
Quote
Exploration of microbial-meteorite redox interactions highlights the possibility of bioprocessing of extraterrestrial metal resources and reveals specific microbial fingerprints left on extraterrestrial material. In the present study, we provide our observations on a microbial-meteorite nanoscale interface of the metal respiring thermoacidophile Metallosphaera sedula. M. sedula colonizes the stony meteorite Northwest Africa 1172 (NWA 1172; an H5 ordinary chondrite) and releases free soluble metals, with Ni ions as the most solubilized. We show the redox route of Ni ions, originating from the metallic Ni° of the meteorite grains and leading to released soluble Ni2+. Nanoscale resolution ultrastructural studies of meteorite grown M. sedula coupled to electron energy loss spectroscopy (EELS) points to the redox processing of Fe-bearing meteorite material. Our investigations validate the ability of M. sedula to perform the biotransformation of meteorite minerals, unravel microbial fingerprints left on meteorite material, and provide the next step towards an understanding of meteorite biogeochemistry. Our findings will serve in defining mineralogical and morphological criteria for the identification of metal-containing microfossils.

https://www.nature.com/articles/s41598-019-54482-7
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/08/2019 08:26 am
Quote
Everything in our Universe is held together or pushed apart by four fundamental forces: gravity, electromagnetism, and two nuclear interactions. Physicists now think they've spotted the actions of a fifth physical force emerging from a helium atom.

https://www.sciencealert.com/physicists-claim-a-they-ve-found-even-more-evidence-of-a-new-force-of-nature

Related paper:

https://arxiv.org/abs/1910.10459

The same group claimed the detection of a 17 MeV vector boson in a slightly different experiment a few years ago already.  Experts were skeptical then and I don't think it's going to be different this time.

That’s not my reading, as from the articles I’ve read it’s being seriously investigated by other teams including at PADME in Frascati, Italy with the experiment being run again next year with improved performance, with the results expected in 2021.
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 12/08/2019 07:01 pm
That’s not my reading, as from the articles I’ve read it’s being seriously investigated by other teams including at PADME in Frascati, Italy with the experiment being run again next year with improved performance, with the results expected in 2021.

People are looking, since it's not a terribly expensive experiment to do (by high-energy physics standards) and it would definitely be extremely interesting if true. However, until some other group confirms the existence of the purported X17 particle, people are going to be sceptical. The group that claims detection has had a bit of a habit of finding stuff the others have never confirmed.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/09/2019 08:14 am
That’s not my reading, as from the articles I’ve read it’s being seriously investigated by other teams including at PADME in Frascati, Italy with the experiment being run again next year with improved performance, with the results expected in 2021.

People are looking, since it's not a terribly expensive experiment to do (by high-energy physics standards) and it would definitely be extremely interesting if true. However, until some other group confirms the existence of the purported X17 particle, people are going to be sceptical. The group that claims detection has had a bit of a habit of finding stuff the others have never confirmed.

Yet I’ve seen their work described as high quality. The first paper was successfully peer reviewed, and the expectation from what I could see wasn’t expected to be any different for this one.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/10/2019 06:45 am
Quote
Washington, DC-- Saturn's icy moon Enceladus is of great interest to scientists due to its subsurface ocean, making it a prime target for those searching for life elsewhere. New research led by Carnegie's Doug Hemingway reveals the physics governing the fissures through which oceanwater erupts from the moon's icy surface, giving its south pole an unusual "tiger stripe" appearance.

https://www.eurekalert.org/pub_releases/2019-12/cifs-heg120619.php

Quote
Scientists may have figured out how dust particles can stick together to form planets, according to a Rutgers co-authored study that may also help to improve industrial processes.

https://www.eurekalert.org/pub_releases/2019-12/ru-hpm120919.php
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/11/2019 07:01 am
Quote
December means chillier climes for northern hemisphere residents, a time to huddle inside near the campfire, both real and cyber. I’ve always thought this was a shame, as the cold crisp nights of winter also offer up sharp, clear skies. Over the past decade or so, December gives observers another reason to brave the cold: the Geminids.

https://www.universetoday.com/144297/december-meteor-squalls-prospects-for-the-2019-geminids-and-ursids/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/14/2019 06:35 am
https://youtu.be/zukBXehGHas
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/14/2019 10:03 pm
https://youtu.be/bwZHzKnEEs4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/16/2019 10:30 am
https://youtu.be/F3HFnfT6Ew4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/17/2019 08:11 pm
Quote
What is really exciting about all of this is that the oxygenation pattern can be created without the need for difficult and complex evolutionary leaps forward, or circumstantial catastrophic volcanic or tectonic events. So it appears that Earth's oxygenation may have been inescapable once photosynthesis had evolved—and the chances of high oxygen worlds existing elsewhere could be much higher.


https://phys.org/news/2019-12-breathable-atmospheres-common-universe-thought.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/17/2019 09:19 pm
Quote
Remember these names -- they may one day trip off the tongue as easily as Mercury, Venus and Mars.

The International Astronomical Union, which is the global authority for naming celestial objects, on Tuesday announced new names for 112 sets of planets and host stars. It said that 780,000 people worldwide in 112 countries had participated in proposing and selecting the names.

https://edition.cnn.com/2019/12/17/world/exoplanets-new-names-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/18/2019 07:02 am
https://youtu.be/ibsWnSH8dDo

Quote
ESO's Very Large Telescope (VLT) has observed the central part of the Milky Way with spectacular resolution and uncovered new details about the history of star birth in our galaxy. Thanks to the new observations, astronomers have found evidence for a dramatic event in the life of the Milky Way: a burst of star formation so intense that it resulted in over a hundred thousand supernova explosions.

https://m.phys.org/news/2019-12-large-telescope-images-stunning-central.html
Title: Re: Astronomy & Planetary Science Thread
Post by: bolun on 12/19/2019 07:40 pm
https://www.nasa.gov/feature/goddard/2019/nasa-s-sdo-sees-new-kind-of-magnetic-explosion-on-sun

Quote
NASA’s Solar Dynamics Observatory has observed a magnetic explosion the likes of which have never been seen before. In the scorching upper reaches of the Sun’s atmosphere, a prominence — a large loop of material launched by an eruption on the solar surface — started falling back to the surface of the Sun. But before it could make it, the prominence ran into a snarl of magnetic field lines, sparking a magnetic explosion.

Scientists have previously seen the explosive snap and realignment of tangled magnetic field lines on the Sun — a process known as magnetic reconnection — but never one that had been triggered by a nearby eruption. The observation, which confirms a decade-old theory, may help scientists understand a key mystery about the Sun’s atmosphere, better predict space weather, and may also lead to breakthroughs in the controlled fusion and lab plasma experiments.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/23/2019 08:12 pm
Quote
One of the brightest stars in the sky -- the nearby red supergiant Betelgeuse in the constellation Orion -- has fainted in recent months, meaning it's significantly less bright than usual and that's leading to some excited speculation the monster star could soon go supernova.

Astronomers from Villanova University reported earlier this month that Betelgeuse is at a "modern all-time low" magnitude, which is a measure of brightness.

One of two things could be happening here: Betelgeuse is a variable star that has been dimming and re-brightening for millennia at this point. We could just be seeing its most significant dip in the past half-century or so, which is less than the blink of an eye in this star's lifespan. Most of the scientists who have chimed in about the big red star in recent weeks on social media believe this is most likely what's going down.

https://www.cnet.com/news/famed-star-betelgeuse-will-explode-some-day-and-its-acting-weird-right-now/
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 12/27/2019 10:14 pm
Quote
One of the brightest stars in the sky -- the nearby red supergiant Betelgeuse in the constellation Orion -- has fainted in recent months, meaning it's significantly less bright than usual and that's leading to some excited speculation the monster star could soon go supernova.

Astronomers from Villanova University reported earlier this month that Betelgeuse is at a "modern all-time low" magnitude, which is a measure of brightness.

One of two things could be happening here: Betelgeuse is a variable star that has been dimming and re-brightening for millennia at this point. We could just be seeing its most significant dip in the past half-century or so, which is less than the blink of an eye in this star's lifespan. Most of the scientists who have chimed in about the big red star in recent weeks on social media believe this is most likely what's going down.

https://www.cnet.com/news/famed-star-betelgeuse-will-explode-some-day-and-its-acting-weird-right-now/

I wondered if anyone noticed the shenanigans in Orion yet.  Should we take bets or poll on if Betelgeuse goes nova sometime in 2020?
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 12/27/2019 11:34 pm
Should we take bets or poll on if Betelgeuse goes nova sometime in 2020?

Imagine trying to accurately forecast the weather 1 month in advance for your town of choice. So... no?
Title: Astronomy & Planetary Science Thread
Post by: Star One on 12/28/2019 06:34 am
Should we take bets or poll on if Betelgeuse goes nova sometime in 2020?

Imagine trying to accurately forecast the weather 1 month in advance for your town of choice. So... no?

The article I posted above actually puts forward a more likely candidate to go nova in the form of Eta Carinae.
Title: Re: Astronomy & Planetary Science Thread
Post by: Stan-1967 on 12/28/2019 07:14 am

I wondered if anyone noticed the shenanigans in Orion yet.  Should we take bets or poll on if Betelgeuse goes nova sometime in 2020?

If I take the "yes" position in the poll, wouldn't I have to wait some 600 years until the light gets here to have the proof I was right?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/28/2019 10:35 pm
Cool Worlds - Tiny Shiny Black Holes:

https://youtu.be/L6GCpvG8xJM
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 12/29/2019 10:18 pm
https://www.youtube.com/watch?v=y1vZ6JT1s8Q
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/30/2019 06:30 am
You just know here’s all of us saying oh it won’t explode, and it probably will just to leave everyone with egg on their faces!
Title: Re: Astronomy & Planetary Science Thread
Post by: RotoSequence on 12/30/2019 07:34 am
You just know here’s all of us saying oh it won’t explode, and it probably will just to leave everyone with egg on their faces!

I don't think you'd find anyone that was happier than the astronomers to be wrong about that.  :P
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/30/2019 05:57 pm
You just know here’s all of us saying oh it won’t explode, and it probably will just to leave everyone with egg on their faces!

I don't think you'd find anyone that was happier than the astronomers to be wrong about that.  :P

What’s it expected to collapse into when it eventually goes supernovae, neutron star or black hole?
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 12/30/2019 06:26 pm
What’s it expected to collapse into when it eventually goes supernovae, neutron star or black hole?

Probably a neutron star ~1.5 M sun
Title: Astronomy & Planetary Science Thread
Post by: Star One on 12/31/2019 08:22 am
Another star that’s been acting very oddly. You can find the history of observations on these links.

http://www.astronomerstelegram.org/?read=13346

http://www.astronomerstelegram.org/?read=13361

http://www.astronomerstelegram.org/?read=13357

https://twitter.com/ProfAbelMendez/status/1204879671193673728

https://twitter.com/ZachWay96/status/1205563372340576256

https://twitter.com/apicasefiles/status/1205587178216132608

https://twitter.com/ZachWay96/status/1207678223158521859

https://twitter.com/superasassn/status/1210932034459320321

https://twitter.com/mattkenworthy/status/1210933414951620610
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 12/31/2019 12:45 pm
Another star that’s been acting very oddly. You can find the history of observations on these links.

http://www.astronomerstelegram.org/?read=13346

http://www.astronomerstelegram.org/?read=13361

http://www.astronomerstelegram.org/?read=13357

https://mobile.twitter.com/ProfAbelMendez/status/1204879671193673728

https://mobile.twitter.com/ZachWay96/status/1205563372340576256

https://mobile.twitter.com/apicasefiles/status/1205587178216132608

https://mobile.twitter.com/ZachWay96/status/1207678223158521859

https://mobile.twitter.com/superasassn/status/1210932034459320321

https://mobile.twitter.com/mattkenworthy/status/1210933414951620610

Tip: remove the "?s=xx" and the URLs work

This latest one suggests it is analogous to Boyajian's Star: https://twitter.com/astronomerstel/status/1211826859496935427

--- Tony
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/31/2019 03:55 pm
Another star that’s been acting very oddly. You can find the history of observations on these links.

http://www.astronomerstelegram.org/?read=13346

http://www.astronomerstelegram.org/?read=13361

http://www.astronomerstelegram.org/?read=13357

https://mobile.twitter.com/ProfAbelMendez/status/1204879671193673728

https://mobile.twitter.com/ZachWay96/status/1205563372340576256

https://mobile.twitter.com/apicasefiles/status/1205587178216132608

https://mobile.twitter.com/ZachWay96/status/1207678223158521859

https://mobile.twitter.com/superasassn/status/1210932034459320321

https://mobile.twitter.com/mattkenworthy/status/1210933414951620610

Tip: remove the "?s=xx" and the URLs work

This latest one suggests it is analogous to Boyajian's Star: https://twitter.com/astronomerstel/status/1211826859496935427

--- Tony


Thanks. I also had to remove the word mobile from the URL to get them to work.

By the way I could see you had been following this story so was hoping you would have a further update.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/31/2019 05:07 pm
Hard to know where really to post this, so I will just put it in here:

https://www.youtube.com/watch?v=mB1nAzriqRQ
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 01/01/2020 01:04 pm
Betelgeuse is almost certainly not going boom today, but will in a (probably distant) tomorrow, but there is a other cool supernova found recently.

Turns out is a a reflection of SN 1987A, 33 years on!

Edit: the thread is well worth reading

https://twitter.com/d_a_howell/status/1212109382814560256

--- Tony
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/02/2020 08:42 pm
https://www.popsci.com/story/space/exoplanet-dark-wasp12b-death/
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 01/04/2020 08:04 am
Quote
A conventional compass would be of little use on the moon, which today lacks a global magnetic field.

But the moon did produce a magnetic field billions of years ago, and it was likely even stronger than the Earth’s field today. Scientists believe that this lunar field, like Earth’s, was generated by a powerful dynamo — the churning of the moon’s core. At some point, this dynamo, and the magnetic field it generated, petered out.

http://news.mit.edu/2019/when-lunar-dynamo-ended-0101

Quote
A team of astronomers at the National Centre for Radio Astrophysics (NCRA) in Pune, India have discovered a mysterious ring of hydrogen gas around a distant galaxy, using the Giant Metrewave Radio Telescope (GMRT). The ring is much bigger than the galaxy it surrounds and has a diameter of about 380,000 light-years (about 4 times that of our Milky Way).

https://www.eurekalert.org/pub_releases/2020-01/tiof-gda010220.php

Quote
In the near future we will have ground- and space-based telescopes that are designed to observe and characterize Earth-like planets. While attention is focused on exoplanets orbiting main sequence stars, more than 150 exoplanets have already been detected orbiting red giants, opening the intriguing question of what rocky worlds orbiting in the habitable zone of red giants would be like and how to characterize them. We model reflection and emission spectra of Earth-like planets orbiting in the habitable zone of red giant hosts with surface temperatures between 5200 and 3900 K at the Earth-equivalent distance, as well as model planet spectra throughout the evolution of their hosts. We present a high-resolution spectral database of Earth-like planets orbiting in the red giant habitable zone from the visible to infrared, to assess the feasibility of characterizing atmospheric features including biosignatures for such planets with upcoming ground- and space-based telescopes such as the Extremely Large Telescopes and the James Webb Space Telescope.

https://arxiv.org/abs/2001.00050

Quote
The Earth’s inner core is hot, under immense pressure and snow-capped, according to new research that could help scientists better understand forces that affect the entire planet.

The snow is made of tiny particles of iron – much heavier than any snowflake on Earth’s surface – that fall from the molten outer core and pile on top of the inner core, creating piles up to 200 miles thick that cover the inner core.

http://www.jsg.utexas.edu/news/2019/12/scientists-find-iron-snow-in-earths-core/

Quote
WASHINGTON, D.C., December 24, 2019 - Chinese researchers have improved the accuracy in detecting space junk in earth's orbit, providing a more effective way to plot safe routes for spacecraft maneuvers.

"The possibility of successfully navigating an asteroid field is approximately 3,720 to one!" exclaimed C-3PO as Han Solo directed the Millennium Falcon into an asteroid field in "Star Wars: The Empire Strikes Back." Earth's orbit is nowhere near as dangerous, but after more than half a century of space activity, collisions between jettisoned engines and disintegrated spacecraft have formed a planetary scrapheap that spacecraft need to evade.

https://www.eurekalert.org/pub_releases/2019-12/aiop-llt122319.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/09/2020 06:39 am
Quote
One of the largest known meteorites to hit Earth struck nearly 800,000 years ago, but the exact spot where it smashed into our planet has been a mystery — until now.

The crater may lie beneath lava in a 910 cubic kilometer (218 cu mi) area of the Bolaven plateau volcanic field in the southeast Asian nation of Laos, according a paper published in the Proceedings of the National Academy of Sciences journal.

https://edition.cnn.com/2020/01/08/asia/australasian-impact-crater-laos-intl-hnk-scli-scn/index.html

Here’s the related paper:

https://www.pnas.org/content/early/2019/12/24/1904368116
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 01/13/2020 07:37 pm
Quote
Jasper Hamill Monday 13 Jan 2020 8:00 pm Stardust that formed to up to seven billion years ago and fell to Earth in a meteorite during the 20th century is now believed to the oldest solid material ever found.

https://metro.co.uk/2020/01/13/stardust-that-fell-to-earth-is-the-oldest-material-ever-found-on-our-planet-scientists-say-12049729/

Quote
There’s a new method to measure the expansion rate of the Universe, but it doesn’t resolve the Crisis in Cosmology

https://www.universetoday.com/144573/theres-a-new-method-to-measure-the-expansion-rate-of-the-universe-but-it-doesnt-resolve-the-crisis-in-cosmology/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/14/2020 05:08 pm
Stars that mysteriously disappear. Related papers linked to in the video description:

https://youtu.be/WeLuc4o59No
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/15/2020 08:36 pm
Quote
Astronomers from UCLA's Galactic Center Orbits Initiative have discovered a new class of bizarre objects at the center of our galaxy, not far from the supermassive black hole called Sagittarius A*. They published their research today in the journal Nature.

"These objects look like gas and behave like stars," said co-author Andrea Ghez, UCLA's Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

The new objects look compact most of the time and stretch out when their orbits bring them closest to the black hole. Their orbits range from about 100 to 1,000 years, said lead author Anna Ciurlo, a UCLA postdoctoral researcher.

https://www.eurekalert.org/pub_releases/2020-01/uoc--adc011320.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2020 11:56 am
Quote
The largest spiral galaxy in the local universe could well earn the nickname “Godzilla Galaxy,” astronomers say, thanks to its truly gargantuan size. The galaxy, UGC 2885, is 2.5 times wider than the Milky way and hosts a trillion stars, 10 times more than Earth’s galactic home. UGC 2885 is located some 232 million light years away in the constellation Perseus.

Quote
“How it got so big is something we don’t quite know yet,” he said. “It’s as big as you can make a disk galaxy without hitting anything else in space.”

UGC 2885 is fairly isolated in space and no nearby galaxies threaten to crash into it or disrupt its spiral disc. It’s not yet clear whether the galaxy cannibalised smaller satellite galaxies over its life or slowly accreted the gas needed to form new stars.

“It seems like it’s been puttering along, slowly growing,” Holwerda said. His team is now counting globular clusters in the galaxy’s halo to determine if they might have been captured from smaller galaxies over billions of years.

https://astronomynow.com/2020/01/06/godzilla-galaxy-one-of-largest-observed-hosts-a-trillion-suns/



Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/26/2020 08:47 am
Have heard of some of these but not others. I imagine with gravity wave astronomy being so new that it alone will add quite a number to such a list.

https://youtu.be/XC4l-L6jXm4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/27/2020 07:51 pm
Quote
Change could be afoot. De Rham has pioneered a radical theory that could hold the key to why the universe is expanding faster and faster and explain the nature of dark energy. The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.

If gravitons have a mass, then gravity is expected to have a weaker influence on very large distance scales, which could explain why the expansion of the universe has not been reined in.

https://www.theguardian.com/science/2020/jan/25/has-physicists-gravity-theory-solved-impossible-dark-energy-riddle
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 01/27/2020 09:41 pm
Quote
Change could be afoot. De Rham has pioneered a radical theory that could hold the key to why the universe is expanding faster and faster and explain the nature of dark energy. The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.

If gravitons have a mass, then gravity is expected to have a weaker influence on very large distance scales, which could explain why the expansion of the universe has not been reined in.

https://www.theguardian.com/science/2020/jan/25/has-physicists-gravity-theory-solved-impossible-dark-energy-riddle

The Guardian is a bit on the hype side. I preferred Jester's take on Massive Gravity from 2018 at Résonaances (https://resonaances.blogspot.com/2018/04/massive-gravity-or-you-only-live-twice.html) and the review arxiv article by de Rham (https://arxiv.org/pdf/1401.4173.pdf). While de Rham's review seems to agree with most likely Graviton masses in Jester's figure, I am not sure about conclusion on coupling strength. In other words,  are there theories left in the sweet spot of Jester's figure, or not? Thoughts?
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/10/2020 05:36 pm
CHIME have discovered that one of the known FRB repeaters has a 16.35 day cycle.

https://www.newsweek.com/mystery-radio-signal-deep-space-16-day-cycle-scientists-1486556

Here’s the related paper:

https://arxiv.org/abs/2001.10275
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/11/2020 07:58 pm
Quote
Three recent studies improve our understanding of environmental conditions on early Earth—important not just for reconstructing the history of our own planet, but for assessing the habitability of planetary bodies in general.

https://www.airspacemag.com/daily-planet/what-was-it-really-early-earth-180974176/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/12/2020 07:54 am
Quote
The Royal Mail has released a set of 8 stamps to commemorate the 200th anniversary of the Royal Astronomical Society. The stamps are designed to illustrate Britain’s contribution to the fields of spaceflight and astronomy, and each depicts a specific cosmic object, phenomenon or space mission.

https://www.skyatnightmagazine.com/space-science/royal-mail-releases-cosmic-stamps-200-years-royal-astronomical-society/
Title: Astronomy & Planetary Science Thread
Post by: Star One on 02/13/2020 07:54 pm
Quote
Citizen scientists have uncovered a bizarre pairing of two brown dwarfs, objects much smaller than the Sun that lack enough mass for nuclear fusion. The discovery, reported in The Astrophysical Journal and confirmed by a scientific team led by astrophysicist Jackie Faherty at the American Museum of Natural History, shows that brown dwarf systems--the formation of which are still poorly understood--can be very low mass and extremely far apart yet inexorably linked.

https://www.eurekalert.org/pub_releases/2020-02/amon-csd021120.php

Quote
Scientists from Rochester Institute of Technology have discovered a newborn massive planet closer to Earth than any other of similarly young age found to date. The baby giant planet, called 2MASS 1155-7919 b, is located in the Epsilon Chamaeleontis Association and lies only about 330 light years from our solar system.

https://www.rit.edu/news/rit-scientists-discover-nearest-known-baby-giant-planet
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/13/2020 10:03 pm
Quote
NASA has confirmed that an asteroid larger than the tallest man-made structure in the world is currently travelling towards Earth at a speed of almost 34,000 miles per hour. Thankfully, it'll likely miss us by a few million miles.
According to International Business Times, NASA's Center for Near-Earth Object Studies (CNEOS) identified that the "potentially hazardous" asteroid could come close to intersecting with our planet's path on February 15, 2020, at 6:05 a.m. (EST).

https://uk.ign.com/articles/nasa-spots-potentially-hazardous-asteroid-rapidly-approaching-earth?sf117407075=1
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/14/2020 03:15 pm
https://www.youtube.com/watch?v=o1ls7Gr9LTE

https://www.youtube.com/watch?v=OjgfS4mYUT4

https://youtu.be/weJG3_XhtL0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/16/2020 07:20 pm
Further to the above videos.

Quote
Betelgeuse isn’t just dimming, it’s also changing shape. Today, the European Southern Observatory released new images of Betelgeuse from the Very Large Telescope (VLT) in Chile’s Atacama desert. The unstable red supergiant is definitely lopsided:

https://spaceweatherarchive.com/2020/02/16/the-changing-shape-of-betelgeuse/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/19/2020 11:22 am
https://youtu.be/8Mk9EHyyFv0
Title: Re: Astronomy & Planetary Science Thread
Post by: Rondaz on 02/20/2020 02:36 pm
Our @ESA_XMM #space observatory has caught a so-called L-dwarf – a star of about 8% the #Sun’s mass – emitting an enormous ‘super flare’ of #Xrays

https://twitter.com/esascience/status/1230502467613470720
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/21/2020 05:48 pm
Quote
A signal originally detected by the Kepler spacecraft has been validated as an exoplanet using the Habitable-zone Planet Finder (HPF), an astronomical spectrograph built by a Penn State team and recently installed on the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas. The HPF provides the highest precision measurements to date of infrared signals from nearby low-mass stars, and astronomers used it to validate the candidate planet by excluding all possibilities of contaminating signals to very high level of probability. The details of the findings appear in the Astronomical Journal.

Quote
“G 9-40b is amongst the top twenty closest transiting planets known, which makes this discovery really exciting,” said Guðmundur Stefánsson, lead author of the paper, and a former PhD student at Penn State who is currently a postdoctoral fellow at Princeton University. “Further, due to its large transit depth, G 9-40b is an excellent candidate exoplanet to study its atmospheric composition with future space telescopes.”

http://science.psu.edu/news/Mahadevan2-2020

Quote
A binary, or double, star system is acting in a very unusual way, according to Chandra data obtained over nearly a decade and a half.

Terzan 5 CX1 is located in a globular cluster about 19,000 light years from Earth and has shown behavior traits of two different types of objects.

Chandra data from 2003 show this system acted as a low-mass X-ray binary, with a neutron star pulling material from a star like the Sun.

Chandra and VLA data between 2009 and 2014 show the system changed into behaving like a millisecond pulsar, then in 2016 went back to acting like a low-mass X-ray binary.

https://chandra.si.edu/photo/2020/terzan5/

https://youtu.be/eecKKfuWdVs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/26/2020 01:08 pm
https://youtu.be/GdahCi9c_78
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/27/2020 05:55 pm
Quote
The biggest cosmic explosion on record has been detected – an event so powerful that it punched a dent the size of 15 Milky Ways in the surrounding space.

The eruption is thought to have originated at a supermassive black hole in the Ophiuchus galaxy cluster, which is about 390m light years from Earth.

https://www.theguardian.com/science/2020/feb/27/biggest-cosmic-explosion-ever-detected-makes-huge-dent-in-space
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2020 08:43 am
Quote
Designated 2020 CD3, so far we know that it's likely a car-sized piece of carbonaceous rock, and has been in orbit for about three years already.

On February 24, the Gemini Observatory in Hawaii took a beautiful colour photo of our new friend, with the 8-meter Gemini North telescope.

https://www.sciencealert.com/here-s-our-cute-little-minimoon-in-colour
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2020 04:48 pm
One possible explanation for Betelgeuse’s dimming:

 https://youtu.be/mnE4RTk3MCU
Title: Re: Astronomy & Planetary Science Thread
Post by: Blackstar on 03/04/2020 10:16 pm
https://www.hou.usra.edu/meetings/lpsc2020/attendee/coronavirus-update.shtml

LPSC Cancellation

March 4, 2020

Dear Colleagues,

We regret to inform you that LPSC 51 will be cancelled due to concerns about COVID-19. This difficult decision has been made after a careful assessment of the risks as determined by the CDC and WHO; consultation with NASA PSD leadership; and consideration of community feedback. We are fully committed to ensuring that our conference attendees remain safe and well.

Please note the following additional information:

    We will reimburse all registration fees, minus a 10% processing fee to cover our costs. We only have a small staff to manage refunds to over 1,600 registrants, so we ask for your patience.
    We will not be able to assist with reimbursement of other travel costs, but the timing of the cancellation should be sufficiently early for attendees to cancel hotel reservations and for the possibility of waived change fees by many airlines.
    We plan to broadcast some of the key NASA and NRC peripheral meetings over the next few weeks; please stay tuned to the LPI and LPSC websites and social media (Twitter: @LPItoday and Facebook: @LunarandPlanetaryInstitute) for more information about scheduling.
    Some of you have asked if we can reschedule the conference; however, given its size there is no way to do this without conflicting with other scheduled meetings or workshops. In addition, we plan to wait for the situation with COVID-19 to settle down before we can consider future venue negotiations.
    We do not see any feasible way at this time to broadcast individual talks or posters; LPSC is simply too large, and we do not have the staff to support these types of activities.
    If you are a student receiving an LPI stipend, we will contact you separately with further instructions.
    If you have any further questions, please email us at [email protected]. We will respond as soon as we are able, but please be patient.

We would like to acknowledge the considerable efforts of the USRA/LPI meetings staff, who have worked for almost a year to produce this conference. We also wish to thank the LPSC Program Committee and its Chair Walter Kiefer, who put together an outstanding program.

Thank you all for your support, and we look forward to seeing you all at LPSC 2021.

Louise Prockter (USRA/LPI) and Eileen Stansbery (JSC/ARES)
LPSC Conference Co-Chairs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/06/2020 11:13 am
Quote
Astronomers know that much about how neutron stars are born. Yet exactly what happens afterwards, inside these ultra-dense cores, remains a mystery. Some researchers theorize that neutrons might dominate all the way down to the centre. Others hypothesize that the incredible pressure compacts the material into more exotic particles or states that squish and deform in unusual ways.

Now, after decades of speculation, researchers are getting closer to solving the enigma, in part thanks to an instrument on the International Space Station called the Neutron Star Interior Composition Explorer (NICER).

https://www.nature.com/articles/d41586-020-00590-8
Title: Astronomy & Planetary Science Thread
Post by: Star One on 03/06/2020 05:13 pm
The Search for Life: Exploring Ocean Worlds:

https://www.youtube.com/watch?v=-BktASuoO8c
Title: Astronomy & Planetary Science Thread
Post by: Star One on 03/11/2020 04:30 pm
WASP-76b:

https://www.youtube.com/watch?v=BAN-l2rkOHE

https://youtu.be/o5eL0f3LPKs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/23/2020 09:46 am
https://www.livescience.com/comet-atlas-may-be-brightenting.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/31/2020 07:12 am
The theory of Massive Gravity:

https://youtu.be/iHh_d45GY10
Title: Re: Astronomy & Planetary Science Thread
Post by: eric z on 03/31/2020 04:10 pm
 I just watched a wonderful show on NHK-TV from Japan, co-hosted by the great Astronaut Naoko Yamazaki, about the new "KAGRA" gravity-wave detector coming on-line in Japan. Fascinating stuff! They also had a short piece on the "MMX" Mars Moon Exploration sample return mission to be launched in 2024 with the "sand" as they referred to it, brought back in 2029. 
  Something to look forward to!  ;D
  Show available on their web site until April 1, 2021.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/31/2020 07:43 pm
Hubble finds evidence of mid-sized black hole:

https://youtu.be/WvnNa1j_bxA
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/01/2020 12:13 pm
https://youtu.be/n9paxdDFdEg
Title: Re: Astronomy & Planetary Science Thread
Post by: RotoSequence on 04/01/2020 02:38 pm
Sounds like they're talking about this?

https://www.nist.gov/video/nists-superconducting-camera-aims-capture-signs-extraterrestrial-life
Title: Re: Astronomy & Planetary Science Thread
Post by: bolun on 04/02/2020 01:24 pm
Space missions return to science (https://www.esa.int/Enabling_Support/Operations/Space_missions_return_to_science)

Quote
After a brief shutdown of science instruments and a period in ‘safe standby’, ESA’s planetary missions are getting back to what they do best, gathering science data from around the Solar System.
Title: Re: Astronomy & Planetary Science Thread
Post by: Norm38 on 04/02/2020 03:17 pm
Has anyone tried viewing Comet Atlas yet?
https://www.newsweek.com/comet-atlas-bright-visible-earth-naked-eye-1493912

I found this site which shows it's currently between Ursa Major and Auriga and Gemini.  Basically straight up after sunset for the northern hemisphere.  I broke out the binoculars last night and didn't see anything fuzzy yet.
https://theskylive.com/planetarium?obj=c2019y4#ra|8.016494858443513|dec|67.33993369312633|fov|39


I'm curious if this will become a naked eye object like some are predicting.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/06/2020 11:10 am
https://www.youtube.com/watch?v=XLbcy8gysBY

Found this new video useful as it finally allowed me to get my head around the concept of frame dragging in space time.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/08/2020 05:13 pm
Comet Atlas maybe fragmenting:

https://spaceweatherarchive.com/2020/04/07/comet-atlas-is-breaking-up/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/10/2020 07:20 am
10 close stars and what are they like:

https://youtu.be/_TB9_NkFIHw
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/13/2020 08:18 am
Cool Worlds - Impossible Moons:

https://www.youtube.com/watch?v=2tteEkzJKiI

Here’s the related paper:

https://arxiv.org/abs/2004.04230
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/13/2020 04:28 pm
NASA Missions Study Shock Waves in Nova Explosion:

https://youtu.be/bsfITaEonlU
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/15/2020 09:48 am
Comet Atlas has fragmented into three pieces:

https://spaceweatherarchive.com/2020/04/14/fragments-of-comet-atlas/
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/15/2020 04:10 pm
Skewed neutrino behavior could help explain matter’s dominion over antimatter

https://www.sciencemag.org/news/2020/04/skewed-neutrino-behavior-could-help-explain-matter-s-dominion-over-antimatter#

Do We Live in a Lopsided Universe?

https://apple.news/AtrgxpOu3Q-u_JVEBqoLFlw
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/16/2020 07:19 am
Interview with Reinhard Genzel (in English):

https://www.youtube.com/watch?v=OgwrnLOXhNA

Related videos:

https://www.youtube.com/watch?v=PR4EzyUv_fs

https://www.youtube.com/watch?v=tVEMu_u2eZA

https://youtu.be/J6rz-3r_ssg
Title: Astronomy & Planetary Science Thread
Post by: Star One on 04/16/2020 02:50 pm
Strange Extragalactic Strands Mystify Astronomers

https://apple.news/ADlxLyJ34QBSE5bHXY6AbOQ

Astronomers spot the brightest supernova ever

https://gizmodo.com/astronomers-spot-the-brightest-supernova-ever-recorded-1842837981
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/17/2020 07:21 am
How Making Antimatter In A Star’s Core Made The Largest Supernova Ever Seen:

https://youtu.be/_cbTwVAN5o0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/23/2020 04:22 pm
https://youtu.be/t03o3T9zXQ8
Title: Re: Astronomy & Planetary Science Thread
Post by: Rondaz on 04/24/2020 05:34 pm
Wow. Asteroid 1998 OR2 tumbling through space seen by the Arecibo observatory.

https://twitter.com/esa/status/1253723123293335553
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/29/2020 08:41 am
https://youtu.be/HBE8qBtQMuA
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/03/2020 03:20 pm
The Discovery of the Long-Period, Eccentric Planet Kepler-88 d and System Characterization with Radial Velocities and Photodynamical Analysis

https://arxiv.org/abs/1909.02427

Why is it so Cold in Here?: Explaining the Cold Temperatures Retrieved from Transmission Spectra of Exoplanet Atmospheres

https://arxiv.org/abs/2003.11548
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/06/2020 02:41 pm
Closest Black Hole to Earth Found:

https://youtu.be/MDFUyxLJEEQ
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 09:19 am
Paper related to the above discovery.

A naked-eye triple system with a nonaccreting black hole in the inner binary⋆,⋆⋆

Abstract
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d binary consisting of a B3 III star and an unseen companion in a circular orbit. The radial-velocity semi-amplitude of 61.3 km s−1 of the inner star and its minimum (probable) mass of 5.0 M⊙ (6.3 ± 0.7 M⊙) imply a mass of the unseen object of ≥4.2 M⊙ (≥5.0 ± 0.4 M⊙), that is, a black hole (BH). The spectroscopic time series is stunningly similar to observations of LB-1. A similar triple-star architecture of LB-1 would reduce the mass of the BH in LB-1 from ∼70 M⊙ to a level more typical of Galactic stellar remnant BHs. The BH in HR 6819 probably is the closest known BH to the Sun, and together with LB-1, suggests a population of quiet BHs. Its embedment in a hierarchical triple structure may be of interest for models of merging double BHs or BH + neutron star binaries. Other triple stars with an outer Be star but without BH are identified; through stripping, such systems may become a source of single Be stars.
Key words: stars: black holes / binaries: spectroscopic / stars: individual: HR 6819 / stars: individual: ALS 8775 (LB-1)
⋆ The authors dedicate this Letter to the memory of Stan Štefl (1955−2014) in sadness and grateful appreciation of his never-tiring alertness that also triggered this work.
⋆⋆ Based partly on observations collected at the European Southern Observatory, Chile (Prop. Nos. 63.H-0080 and 073.D-0274).

https://www.aanda.org/articles/aa/full_html/2020/05/aa38020-20/aa38020-20.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 09:23 am
The hidden companion in LB-1 unveiled by spectral disentangling

The intriguing binary LS V + 22 25 (LB-1) drew much attention after being claimed to be a 79-day binary comprising a B-type star orbiting a ~70Ms black hole - the most massive stellar black hole reported to date. Subsequent studies showed that evidence for such a large companion mass is lacking. Recent analyses implied that the primary star is a stripped, He-rich star with peculiar sub-solar abundances of heavy elements such as Mg and Fe. However, the nature of the secondary, which was proposed to be a black hole, a neutron star, or a main sequence star, remains unknown. Relying on 26 newly acquired spectroscopic observations secured with the HERMES and FEROS spectrographs, we perform an orbital analysis and spectral disentangling of LB-1 to elucidate the nature of the system.
We find that LB-1 contains two non-degenerate stars. The "hidden" secondary is a rapidly rotating (vsini ~ 300 km/s) B3 V star with a decretion disk - a Be star. The properties of the primary match those predicted for stripped stars: it is He- and N-rich and portrays significant Balmer-line emission, presumably stemming from its wind. Adopting a light contribution in the optical of 55% for the stripped primary, the abundances of heavy elements are found to be solar. With the derived value of K2 = 11.2 +- 1.0 km/s and by calibrating the mass of the B3 Ve secondary to M2 = 7 +- 2Ms, we derive an orbital mass for the stripped primary of M1 = 1.5 +- 0.4Ms. The orbital inclination of 39 +- 4deg implies a near-critical rotation for the Be secondary Veq ~ 470 km/s.
Hence, LB-1 does not contain a compact object. Instead, it is a rare Be binary system consisting of a stripped donor star and a Be mass accretor rotating at near its critical velocity. This system is a clear example that binary interactions play a decisive role in the production of rapid stellar rotators and Be stars.

https://arxiv.org/abs/2004.12882
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 09:31 am
Detection of Polarization due to Cloud Bands in the Nearby Luhman 16 Brown Dwarf Binary

Brown dwarfs exhibit patchy or spatially varying banded cloud structures that are inferred through photometric and spectroscopic variability modeling techniques. However, these methods are insensitive to rotationally invariant structures, such as the bands seen in Jupiter. Here, we present H-band Very Large Telescope/NaCo linear polarization measurements of the nearby Luhman 16 L/T transition binary, which suggest that Luhman 16A exhibits constant longitudinal cloud bands. The instrument was operated in pupil tracking mode, allowing us to unambiguously distinguish between a small astrophysical polarization and the ~2% instrumental linear polarization. We measure the degree and angle of linear polarization of Luhman 16A and B to be p A  = 0.031%  ± 0.004% and ψ A  = −32° ± 4°, and p B  = 0.010%  ± 0.004% and ${\psi }_{B}={73}_{-11}^{+13\circ} $, respectively. Using known physical parameters of the system, we demonstrate that an oblate homogeneous atmosphere cannot account for the polarization measured in Luhman 16A, but could be responsible for that of the B component. Through a nonexhaustive search of banded cloud morphologies, we demonstrate a two-banded scenario that can achieve a degree of linear polarization of p = 0.03% and conclude that the measured polarization of the A component must be predominantly due to cloud banding. For Luhman 16B, either oblateness or cloud banding could be the dominant source of the measured polarization. The misaligned polarization angles of the two binary components tentatively suggest spin–orbit misalignment. These measurements provide new evidence for the prevalence of cloud banding in brown dwarfs while at the same time demonstrating a new method—complementary to photometric and spectroscopic variability methods—for characterizing the cloud morphologies of substellar objects without signs of variability.

https://iopscience.iop.org/article/10.3847/1538-4357/ab6ef2
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 09:43 am
An interstellar origin for high-inclination Centaurs

We investigate the possible origins of real high-inclination Centaurs and trans-neptunian objects using a high-resolution statistical search for stable orbits that simulates their evolution back in time to the epoch when planet formation ended 4.5 billion years in the past. The simulation is a precise orbit determination method that does not involve ad hoc initial conditions or assumptions such as those found in planetesimal disk relaxation models upon which their conclusions depend. It can therefore be used to independently test origin theories based on relaxation models by examining the past orbits of specific real objects. Here, we examined 17 multiple-opposition high-inclination Centaurs and the two polar trans-neptunian objects 2008 KV42 and (471325) 2011 KT19. The statistical distributions show that their orbits were nearly polar 4.5 Gyr in the past, and were located in the scattered disk and inner Oort cloud regions. Early polar inclinations cannot be accounted for by current Solar system formation theory as the early planetesimal system must have been nearly flat in order to explain the low-inclination asteroid and Kuiper belts. Furthermore, the early scattered disk and inner Oort cloud regions are believed to have been devoid of Solar system material as the planetesimal disk could not have extended far beyond Neptune's current orbit in order to halt the planet's outward migration. The nearly polar orbits of high-inclination Centaurs 4.5 Gyr in the past therefore indicate their probable early capture from the interstellar medium.

https://arxiv.org/abs/2004.10510
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 09:49 am
Is Comet SWAN Fragmenting? Astronomers Detect Powerful Outburst

https://www.ibtimes.com/comet-swan-fragmenting-astronomers-detect-powerful-outburst-2971687
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/09/2020 10:16 am
The SOPHIE search for northern extrasolar planets. XVI. HD 158259: A compact planetary system in a near-3:2 mean motion resonance chain

Since 2011, the SOPHIE spectrograph has been used to search for Neptunes and super-Earths in the Northern Hemisphere. As part of this observational program, 290 radial velocity measurements of the 6.4 V magnitude star HD 158259 were obtained. Additionally, TESS photometric measurements of this target are available. We present an analysis of the SOPHIE data and compare our results with the output of the TESS pipeline. The radial velocity data, ancillary spectroscopic indices, and ground-based photometric measurements were analyzed with classical and 1 periodograms. The stellar activity was modeled as a correlated Gaussian noise and its impact on the planet detection was measured with a new technique. The SOPHIE data support the detection of five planets, each with msini≈6M⊕, orbiting HD 158259 in 3.4, 5.2, 7.9, 12, and 17.4 days. Though a planetary origin is strongly favored, the 17.4 d signal is classified as a planet candidate due to a slightly lower statistical significance and to its proximity to the expected stellar rotation period. The data also present low frequency variations, most likely originating from a magnetic cycle and instrument systematics. Furthermore, the TESS pipeline reports a significant signal at 2.17 days corresponding to a planet of radius ≈1.2R⊕. A compatible signal is seen in the radial velocities, which confirms the detection of an additional planet and yields a ≈2M⊕ mass estimate. We find a system of five planets and a strong candidate near a 3:2 mean motion resonance chain orbiting HD 158259. The planets are found to be outside of the two and three body resonances.

https://arxiv.org/abs/1911.13296
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/10/2020 02:52 pm
Is GRB 110715A the progenitor of FRB 171209?

The physical origin of fast radio bursts (FRBs) is unknown. Young magnetars born from gamma-ray bursts (GRBs) have been suggested to be a possible central engine of FRBs. We test such a hypothesis by systematically searching for GRB-FRB spatial associations from 110 FRBs and 1440 GRBs. We find that one FRB event, FRB 171209, discovered by the Parkes telescope is spatially coincident with a historical long-duration GRB 110715A at z=0.82. The afterglow of GRB 110715A is consistent with being powered by a millisecond magnetar. The extragalactic dispersion measure of FRB 171209 is in excess of that contributed by the intergalactic medium, which can be interpreted as being contributed by a young supernova remnant associated with the GRB. Overall, the significance of the association is (2.28−2.55)σ. If the association is indeed physical, our result suggests that the magnetars associated with long GRBs can be the progenitors of at least some FRBs.

https://arxiv.org/abs/2004.12050v1

The Sun is less active than other solar-like stars

Abstract
The magnetic activity of the Sun and other stars causes their brightness to vary. We investigated how typical the Sun’s variability is compared with other solar-like stars, i.e., those with near-solar effective temperatures and rotation periods. By combining 4 years of photometric observations from the Kepler space telescope with astrometric data from the Gaia spacecraft, we were able to measure photometric variabilities of 369 solar-like stars. Most of those with well-determined rotation periods showed higher variability than the Sun and are therefore considerably more active. These stars appear nearly identical to the Sun except for their higher variability. Therefore, we speculate that the Sun could potentially also go through epochs of such high variability.

https://science.sciencemag.org/content/368/6490/518
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/15/2020 06:39 pm
KAGUYA observation of global emissions of indigenous carbon ions from the Moon

Abstract
Carbon is a volatile element that has a considerable influence on the formation and evolution of planetary bodies, although it was previously believed to be depleted in the Moon. We present observations by the lunar orbiter KAGUYA of carbon ions emitted from the Moon. These emissions were distributed over almost the total lunar surface, but amounts were differed with respect to lunar geographical areas. The estimated emission fluxes to space were ~5.0 × 104 per square centimeter per second, which is greater than possible ongoing supplies from the solar wind and micrometeoroids. Our estimates demonstrate that indigenous carbon exists over the entire Moon, supporting the hypothesis of a carbon-containing Moon, where the carbon was embedded at its formation and/or was transported billions of years ago.

https://advances.sciencemag.org/content/6/19/eaba1050
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/16/2020 11:05 am
An Active Plume Eruption on Europa During Galileo Flyby E26 as Indicated by Energetic Proton Depletions

Abstract
Strong depletions of energetic protons (115–244 keV) were observed during Galileo flyby E26 of Europa. We simulate the flux of energetic protons using a Monte Carlo particle backtracing code and show that energetic proton depletions during E26 are reproduced by taking into account the perturbations of the electromagnetic fields calculated by magnetohydrodynamic (MHD) simulations and charge exchange with a global atmosphere and plume. A depletion feature occurring shortly after closest approach is driven by plume associated charge exchange, or a combination with plume associated field perturbations. We therefore conclude, with a new method and independent data set, that Galileo could have encountered a plume during E26.

Plain Language Summary
We investigate why (normally abundant) fast protons were disappearing during Europa flyby E26 by Galileo. We do this by simulating the proton motion. In some cases we detect few protons because Europa is blocking the field of view. What is new here is that part of the decrease can be explained by charge exchange, a process whereby the protons are removed after they lose their electrical charge in Europa's thin atmosphere. Furthermore, we see that there is a special decrease, which can be explained by an erupting plume of water vapor, thereby providing additional evidence for an active plume during Galileo flyby E26.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087806
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/16/2020 11:11 am
Observational evidence for the origin of high-energy neutrinos in parsec-scale nuclei of radio-bright active galaxies

Observational information on high-energy astrophysical neutrinos is being continuously collected by the IceCube observatory. However, the sources of neutrinos are still unknown. In this study, we use radio very-long-baseline interferometry (VLBI) data for a complete VLBI-flux-density limited sample of active galactic nuclei (AGN). We address the problem of the origin of astrophysical neutrinos with energies above 200 TeV in a statistical manner. It is found that AGN positionally associated with IceCube events have typically stronger parsec-scale cores than the rest of the sample. The post-trial probability of a chance coincidence is 0.2%. We select the four strongest AGN as highly probable associations: 3C 279, NRAO 530, PKS 1741-038, and OR 103. Moreover, we find an increase of radio emission at frequencies above 10 GHz around neutrino arrival times for several other VLBI-selected AGN on the basis of RATAN-600 monitoring. The most pronounced example of such behavior is PKS 1502+106. We conclude that AGN with bright Doppler-boosted jets constitute an important population of neutrino sources. High-energy neutrinos are produced in their central parsec-scale regions, probably in proton-photon interactions at or around the accretion disk. Radio-bright AGN that are likely associated with neutrinos have very diverse gamma-ray properties suggesting that gamma-rays and neutrinos may be produced in different regions of AGN and not directly related. A small viewing angle of the jet-disk axis is, however, required to detect either of them.

https://arxiv.org/abs/2001.00930
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/19/2020 02:48 pm
Counting Comets:

https://youtu.be/JpMo4lhEvEs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/19/2020 03:45 pm
Sustained fluvial deposition recorded in Mars’ Noachian stratigraphic record

Orbital observation has revealed a rich record of fluvial landforms on Mars, with much of this record dating 3.6–3.0 Ga. Despite widespread geomorphic evidence, few analyses of Mars’ alluvial sedimentary-stratigraphic record exist, with detailed studies of alluvium largely limited to smaller sand-bodies amenable to study in-situ by rovers. These typically metre-scale outcrop dimensions have prevented interpretation of larger scale channel-morphology and long-term basin evolution, vital for understanding the past Martian climate. Here we give an interpretation of a large sedimentary succession at Izola mensa within the NW Hellas Basin rim. The succession comprises channel and barform packages which together demonstrate that river deposition was already well established &gt;3.7 Ga. The deposits mirror terrestrial analogues subject to low-peak discharge variation, implying that river deposition at Izola was subject to sustained, potentially perennial, fluvial flow. Such conditions would require an environment capable of maintaining large volumes of water for extensive time-periods, necessitating a precipitation-driven hydrological cycle.

https://www.nature.com/articles/s41467-020-15622-0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/20/2020 01:36 pm
https://youtu.be/nN_0tZ-a570
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/21/2020 03:20 pm
Evidence for Spin–Orbit Alignment in the TRAPPIST-1 System

Abstract
In an effort to measure the Rossiter–McLaughlin effect for the TRAPPIST-1 system, we performed high-resolution spectroscopy during transits of planets e, f, and b. The spectra were obtained with the InfraRed Doppler spectrograph on the Subaru 8.2 m telescope, and were supplemented with simultaneous photometry obtained with a 1 m telescope of the Las Cumbres Observatory Global Telescope. By analyzing the anomalous radial velocities, we found the projected stellar obliquity to be λ = 1 ± 28° under the assumption that the three planets have coplanar orbits, although we caution that the radial-velocity data show correlated noise of unknown origin. We also sought evidence for the expected deformations of the stellar absorption lines, and thereby detected the "Doppler shadow" of planet b with a false-alarm probability of 1.7%. The joint analysis of the observed residual cross-correlation map including the three transits gave $\lambda ={19}_{-15}^{+13}$°. These results indicate that the the TRAPPIST-1 star is not strongly misaligned with the common orbital plane of the planets, although further observations are encouraged to verify this conclusion.

https://iopscience.iop.org/article/10.3847/2041-8213/ab74dc
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/21/2020 06:46 pm
UH ATLAS telescope discovers first-of-its-kind asteroid

http://www.ifa.hawaii.edu/info/press-releases/2019LD2/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2020 07:57 am
A heatwave of accretion energy traced by masers in the G358-MM1 high-mass protostar

Abstract
High-mass stars are thought to accumulate much of their mass via short, infrequent bursts of disk-aided accretion1,2. Such accretion events are rare and difficult to observe directly but are known to drive enhanced maser emission3,4,5,6. In this Letter we report high-resolution, multi-epoch methanol maser observations toward G358.93-0.03, which reveal an interesting phenomenon: the subluminal propagation of a thermal radiation ‘heatwave’ emanating from an accreting high-mass protostar. The extreme transformation of the maser emission implies a sudden intensification of thermal infrared radiation from within the inner (40-mas, 270-au) region. Subsequently, methanol masers trace the radial passage of thermal radiation through the environment at ≥4% of the speed of light. Such a high translocation rate contrasts with the ≤10 km s−1 physical gas motions of methanol masers typically observed using very-long-baseline interferometry (VLBI). The observed scenario can readily be attributed to an accretion event in the high-mass protostar G358.93-0.03-MM1. While being the third case in its class, G358.93-0.03-MM1 exhibits unique attributes hinting at a possible ‘zoo’ of accretion burst types. These results promote the advantages of maser observations in understanding high-mass-star formation, both through single-dish maser monitoring campaigns and via their international cooperation as VLBI arrays.

https://www.nature.com/articles/s41550-019-0989-3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2020 08:00 am
The Bold Plan to See Continents and Oceans on Another Earth

https://www.planetary.org/blogs/guest-blogs/sharp-image-earth-like-exoplanet.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2020 08:56 am
The Chiral Puzzle of Life

Abstract
Biological molecules chose one of two structurally chiral systems which are related by reflection in a mirror. It is proposed that this choice was made, causally, by cosmic rays, which are known to play a major role in mutagenesis. It is shown that magnetically polarized cosmic rays that dominate at ground level today can impose a small, but persistent, chiral bias in the rate at which they induce structural changes in simple, chiral monomers that are the building blocks of biopolymers. A much larger effect should be present with helical biopolymers, in particular, those that may have been the progenitors of ribonucleic acid and deoxyribonucleic acid. It is shown that the interaction can be both electrostatic, just involving the molecular electric field, and electromagnetic, also involving a magnetic field. It is argued that this bias can lead to the emergence of a single, chiral life form over an evolutionary timescale. If this mechanism dominates, then the handedness of living systems should be universal. Experiments are proposed to assess the efficacy of this process.

https://iopscience.iop.org/article/10.3847/2041-8213/ab8dc6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/25/2020 01:41 pm
Experimental evidence for lava-like mud flows under Martian surface conditions

Abstract

Large outflow channels on ancient terrains of Mars have been interpreted as the products of catastrophic flood events. The rapid burial of water-rich sediments after such flooding could have led to sedimentary volcanism, in which mixtures of sediment and water (mud) erupt to the surface. Tens of thousands of volcano-like landforms populate the northern lowlands and other local sedimentary depocentres on Mars. However, it is difficult to determine whether the edifices are related to igneous or mud extrusions, partly because the behaviour of extruded mud under Martian surface conditions is poorly constrained. Here we investigate the mechanisms of mud propagation on Mars using experiments performed inside a low-pressure chamber at cold temperatures. We found that low viscosity mud under Martian conditions propagates differently from that on Earth, because of a rapid freezing and the formation of an icy crust. Instead, the experimental mud flows propagate like terrestrial pahoehoe lava flows, with liquid mud spilling from ruptures in the frozen crust, and then refreezing to form a new flow lobe. We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to cryovolcanic extrusions on icy bodies in the Solar System.

https://www.nature.com/articles/s41561-020-0577-2
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/27/2020 03:35 pm
A census of baryons in the Universe from localized fast radio bursts

Abstract
More than three-quarters of the baryonic content of the Universe resides in a highly diffuse state that is difficult to detect, with only a small fraction directly observed in galaxies and galaxy clusters1,2. Censuses of the nearby Universe have used absorption line spectroscopy3,4 to observe the ‘invisible’ baryons, but these measurements rely on large and uncertain corrections and are insensitive to most of the Universe’s volume and probably most of its mass. In particular, quasar spectroscopy is sensitive either to the very small amounts of hydrogen that exist in the atomic state, or to highly ionized and enriched gas4,5,6 in denser regions near galaxies7. Other techniques to observe these invisible baryons also have limitations; Sunyaev–Zel’dovich analyses8,9 can provide evidence from gas within filamentary structures, and studies of X-ray emission are most sensitive to gas near galaxy clusters9,10. Here we report a measurement of the baryon content of the Universe using the dispersion of a sample of localized fast radio bursts; this technique determines the electron column density along each line of sight and accounts for every ionized baryon11,12,13. We augment the sample of reported arcsecond-localized14,15,16,17,18 fast radio bursts with four new localizations in host galaxies that have measured redshifts of 0.291, 0.118, 0.378 and 0.522. This completes a sample sufficiently large to account for dispersion variations along the lines of sight and in the host-galaxy environments11, and we derive a cosmic baryon density of 𝛺b=0.051+0.021−0.025ℎ−170
Ω
b
=
0.051

0.025
+
0.021
h
70

1
(95 per cent confidence; h70 = H0/(70 km s−1 Mpc−1) and H0 is Hubble’s constant). This independent measurement is consistent with values derived from the cosmic microwave background and from Big Bang nucleosynthesis19,20.

https://www.nature.com/articles/s41586-020-2300-2

Press release:

https://www.icrar.org/MissingMatter/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/27/2020 03:51 pm
Links to the various papers referenced can be found in the article.

Unexplained Phenomena Keep Suggesting the Universe Isn’t What We Thought

https://www.vice.com/en_uk/article/3azqq3/unexplained-phenomena-keep-suggesting-the-universe-isnt-what-we-thought
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/28/2020 02:50 pm
Two related papers:

A Mildly Relativistic Outflow from the Energetic, Fast-rising Blue Optical Transient CSS161010 in a Dwarf Galaxy

Abstract
We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010 J045834−081803 (CSS161010 hereafter) at t = 69–531 days. CSS161010 shows luminous X-ray (L x ~ 5 × 1039 erg s−1) and radio (L ν  ~ 1029 erg s−1 Hz−1) emission. The radio emission peaked at ~100 days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity Γβc ≥ 0.55c at ~100 days. This is faster than the non-relativistic AT 2018cow (Γβc ~ 0.1c) and closer to ZTF18abvkwla (Γβc ≥ 0.3c at 63 days). The inferred initial kinetic energy of CSS161010 (E k  gsim 1051 erg) is comparable to that of long gamma-ray bursts, but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger ($\sim 0.01\mbox{--}0.1\,{M}_{\odot }$). This is consistent with the lack of observed γ-rays. The luminous X-rays were produced by a different emission component to the synchrotron radio emission. CSS161010 is located at ~150 Mpc in a dwarf galaxy with stellar mass M * ~ 107 M  and specific star formation rate sSFR ~ 0.3 Gyr−1. This mass is among the lowest inferred for host galaxies of explosive transients from massive stars. Our observations of CSS161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a H-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally located intermediate-mass black hole. Regardless of the physical mechanism, CSS161010 establishes the existence of a new class of rare (rate &lt; 0.4% of the local core-collapse supernova rate) H-rich transients that can launch mildly relativistic outflows.

https://iopscience.iop.org/article/10.3847/2041-8213/ab8cc7

The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at z = 0.27

Abstract
We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT 2018cow: blue colors at peak ($g-r\approx -0.5$ mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity (${M}_{g,\mathrm{peak}}\approx -20.6$ mag), a hot (gsim40,000 K) featureless spectrum at peak light, and a luminous radio counterpart. At late times (${\rm{\Delta }}t\gt 80\,\mathrm{days}$), the radio luminosity of ZTF18abvkwla ($\nu {L}_{\nu }\gtrsim {10}^{40}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ at 10 $\mathrm{GHz}$, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy ($M\approx 5\times {10}^{8}\,{M}_{\odot }$, $\mathrm{SFR}\approx 7\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$) that is moderately metal-enriched ($\mathrm{log}[{\rm{O}}/{\rm{H}}]\approx 8.5$), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast-moving ejecta (${\rm{\Gamma }}\beta c\gt 0.38c$) and the optical from shock-interaction with confined dense material (&lt;0.07 M  in $\sim {10}^{15}\,\mathrm{cm}$). Compiling transients in the literature with ${t}_{\mathrm{rise}}\lt 5\,\mathrm{days}$ and ${M}_{\mathrm{peak}}\lt -20$ mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, as well as prospects for detecting accompanying X-ray and radio emission.

https://iopscience.iop.org/article/10.3847/1538-4357/ab8bcf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/28/2020 05:05 pm
The large Trans-Neptunian Object 2002 TC302 from combined stellar occultation, photometry and astrometry data

On 28th January 2018, the large Trans-Neptunian Object (TNO) 2002TC302 occulted a mv=15.3 star with ID 130957813463146112 in the Gaia DR2 stellar catalog. 12 positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, 4 negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a TNO other than Pluto, in terms of the number of chords published thus far. From the 12 chords, an accurate elliptical fit to the instantaneous projection of the body, compatible with the near misses, can be obtained. The resulting ellipse has major and minor axes of 543 ± 18 km and 460 ± 11 km, respectively, with a position angle of 3 ± 1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5m telescope at Sierra Nevada Observatory and the 1.23m telescope at Calar Alto observatory, allows us to derive possible 3D shapes and density estimations for the body, based on hydrostatic equilibrium assumptions. The effective area equivalent diameter is ∼ 84 km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to ∼ 300 km in diameter, to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal results. The existence of a potential satellite also appears to be consistent with other ground-based data presented here. From the effective occultation diameter combined with HV measurements we derive a geometric albedo of 0.147 ± 0.005, which would be somewhat smaller if 2002TC302 has a satellite. The best occultation light curves do not show any signs of ring features or any signatures of a global atmosphere.

https://arxiv.org/abs/2005.08881
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/01/2020 03:09 pm
Aerosol composition of hot giant exoplanets dominated by silicates and hydrocarbon hazes

Abstract
Aerosols are common in the atmospheres of exoplanets across a wide swath of temperatures, masses and ages1,2,3. These aerosols strongly impact observations of transmitted, reflected and emitted light from exoplanets, obfuscating our understanding of exoplanet thermal structure and composition4,5,6. Knowing the dominant aerosol composition would facilitate interpretations of exoplanet observations and theoretical understanding of their atmospheres. A variety of compositions have been proposed, including metal oxides and sulfides, iron, chromium, sulfur and hydrocarbons7,8,9,10,11. However, the relative contributions of these species to exoplanet aerosol opacity is unknown. Here we show that the aerosol composition of giant exoplanets observed in transmission is dominated by silicates and hydrocarbons. By constraining an aerosol microphysics model with trends in giant exoplanet transmission spectra, we find that silicates dominate aerosol opacity above planetary equilibrium temperatures of 950 K due to low nucleation energy barriers and high elemental abundances, while hydrocarbon aerosols dominate below 950 K due to an increase in methane abundance. Our results are robust to variations in planet gravity and atmospheric metallicity within the range of most giant transiting exoplanets. We predict that spectral signatures of condensed silicates in the mid-infrared are most prominent for hot (>1,600 K), low-gravity (<10 m s−2) objects.

https://www.nature.com/articles/s41550-020-1114-3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/01/2020 03:21 pm
https://youtu.be/bvzuviHxnIo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/01/2020 06:45 pm
The Milky Way has one very hot halo, astronomers find

Quote
The halo that surrounds our own Milky Way galaxy is much hotter than scientists once believed—and it may not be unique among galaxies.

https://phys.org/news/2020-06-milky-hot-halo-astronomers.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/03/2020 06:58 pm
Zooming in on the origins of fast radio bursts

Quote
Astronomers have peered into the home galaxies of fast radio bursts, ruling out supermassive black holes as a cause and bringing us a step closer to understanding the origins of these mysterious signals from outer space.

https://www.csiro.au/en/News/News-releases/2020/Zooming-in-on-the-origins-of-fast-radio-bursts
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/04/2020 07:12 pm
Transit least-squares survey

III. A 1.9 R⊕ transit candidate in the habitable zone of Kepler-160 and a nontransiting planet characterized by transit-timing variations


Abstract
The Sun-like star Kepler-160 (KOI-456) has been known to host two transiting planets, Kepler-160 b and c, of which planet c shows substantial transit-timing variations (TTVs). We studied the transit photometry and the TTVs of this system in our search for a suspected third planet. We used the archival Kepler photometry of Kepler-160 to search for additional transiting planets using a combination of our Wtan detrending algorithm and our transit least-squares detection algorithm. We also used the Mercury N-body gravity code to study the orbital dynamics of the system in trying to explain the observed TTVs of planet c. First, we recovered the known transit series of planets Kepler-160 b and c. Then we found a new transiting candidate with a radius of 1.91−0.14+0.17 Earth radii (R⊕), an orbital period of 378.417−0.025+0.028 d, and Earth-like insolation. The vespa software predicts that this signal has an astrophysical false-positive probability of FPP3 = 1.8 × 10−3 when the multiplicity of the system is taken into account. Kepler vetting diagnostics yield a multiple event statistic of MES = 10.7, which corresponds to an ~85% reliability against false alarms due to instrumental artifacts such as rolling bands. We are also able to explain the observed TTVs of planet c with the presence of a previously unknown planet. The period and mass of this new planet, however, do not match the period and mass of the new transit candidate. Our Markov chain Monte Carlo simulations of the TTVs of Kepler-160 c can be conclusively explained by a new nontransiting planet with a mass between about 1 and 100 Earth masses and an orbital period between about 7 and 50 d. We conclude that Kepler-160 has at least three planets, one of which is the nontransiting planet Kepler-160 d. The expected stellar radial velocity amplitude caused by this new planet ranges between about 1 and 20 m s−1. We also find the super-Earth-sized transiting planet candidate KOI-456.04 in the habitable zone of this system, which could be the fourth planet.

https://www.aanda.org/articles/aa/full_html/2020/06/aa36929-19/aa36929-19.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2020 03:25 pm
Demonstrating high-precision photometry with a CubeSat: ASTERIA observations of 55 Cancri e

ASTERIA (Arcsecond Space Telescope Enabling Research In Astrophysics) is a 6U CubeSat space telescope (10 cm x 20 cm x 30 cm, 10 kg). ASTERIA's primary mission objective was demonstrating two key technologies for reducing systematic noise in photometric observations: high-precision pointing control and high-stabilty thermal control. ASTERIA demonstrated 0.5 arcsecond RMS pointing stability and ±10 milliKelvin thermal control of its camera payload during its primary mission, a significant improvement in pointing and thermal performance compared to other spacecraft in ASTERIA's size and mass class. ASTERIA launched in August 2017 and deployed from the International Space Station (ISS) November 2017. During the prime mission (November 2017 -- February 2018) and the first extended mission that followed (March 2018 - May 2018), ASTERIA conducted opportunistic science observations which included collection of photometric data on 55 Cancri, a nearby exoplanetary system with a super-Earth transiting planet. The 55 Cancri data were reduced using a custom pipeline to correct CMOS detector column-dependent gain variations. A Markov Chain Monte Carlo (MCMC) approach was used to simultaneously detrend the photometry using a simple baseline model and fit a transit model. ASTERIA made a marginal detection of the known transiting exoplanet 55 Cancri e (∼2~\Rearth), measuring a transit depth of 374±170 ppm. This is the first detection of an exoplanet transit by a CubeSat. The successful detection of super-Earth 55 Cancri e demonstrates that small, inexpensive spacecraft can deliver high-precision photometric measurements.

https://arxiv.org/abs/2005.14155
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/08/2020 08:37 pm
Possible periodic activity in the repeating FRB 121102

ABSTRACT
The discovery that at least some Fast Radio Bursts (FRBs) repeat has ruled out cataclysmic events as the progenitors of these particular bursts. FRB 121102 is the most well-studied repeating FRB but despite extensive monitoring of the source, no underlying pattern in the repetition has previously been identified. Here, we present the results from a radio monitoring campaign of FRB 121102 using the 76 m Lovell telescope. Using the pulses detected in the Lovell data along with pulses from the literature, we report a detection of periodic behaviour of the source over the span of 5 yr of data. We predict that the source is currently ‘off’ and that it should turn ‘on’ for the approximate MJD range 59002−59089 (2020 June 2 to 2020 August 28). This result, along with the recent detection of periodicity from another repeating FRB, highlights the need for long-term monitoring of repeating FRBs at a high cadence. Using simulations, we show that one needs at least 100 h of telescope time to follow-up repeating FRBs at a cadence of 0.5–3 d to detect periodicities in the range of 10–150 d. If the period is real, it shows that repeating FRBs can have a large range in their activity periods that might be difficult to reconcile with neutron star precession models.

https://academic.oup.com/mnras/article/495/4/3551/5840547?searchresult=1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/11/2020 10:04 pm
Bizarre nearby star offers clues to origins of mysterious fast radio bursts

https://www.nature.com/articles/d41586-020-01666-1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/12/2020 03:56 pm
Scientists Detect Unexpected Widespread Structures Near Earth’s Core

Quote
University of Maryland researchers conduct first simultaneous analysis of hundreds of earthquakes to identify echoes from features deep inside Earth

https://cmns.umd.edu/news-events/features/4604
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/14/2020 11:07 am
Quantifying the Solar Cycle Modulation of Extreme Space Weather

Extreme space weather events or superstorms have a high impact over a wide range of systems, from power supplies, aviation, satellites, and radio communications to economic and social behavior. They are becoming increasingly important as our society relies more and more on being interconnected. While it is well known that severe space weather activity is modulated by the solar cycle, the variable duration of the cycle has made this risk difficult to quantify and there is still the possibility of a severe event during solar minimum. Quantifying the relative likelihood of severe space weather events at different phases of the solar cycle is a key result of this work. We map this irregular cycle in time onto a uniform solar cycle clock and find a quite strong solar cycle modulation, with only a few percent of the most severe solar flares and space storms occurring during the minimum quiet interval of the cycle, the timing of which we have identified. This has operational implications for the users of nearEarth space as well as power grid operators who need to schedule critical maintenance during periods of quiet space weather.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087795
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/15/2020 04:27 pm
Venus in a Minute:

https://youtu.be/wbG1DK92OVE
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/17/2020 03:59 pm
Resonance locking in giant planets indicated by the rapid orbital expansion of Titan

Abstract
Saturn is orbited by dozens of moons, and the intricate dynamics of this complex system provide clues about its formation and evolution. Tidal friction within Saturn causes its moons to migrate outwards, driving them into orbital resonances that pump their eccentricities or inclinations, which in turn leads to tidal heating of the moons. However, in giant planets, the dissipative processes that determine the tidal migration timescale remain poorly understood. Standard theories suggest an orbital expansion rate inversely proportional to the power 11/2 in distance1, implying negligible migration for outer moons such as Saturn’s largest moon, Titan. Here, we use two independent measurements obtained with the Cassini spacecraft to measure Titan’s orbital expansion rate. We find that Titan rapidly migrates away from Saturn on a timescale of roughly ten billion years, corresponding to a tidal quality factor of Saturn of Q ≃ 100, which is more than a hundred times smaller than most expectations. Our results for Titan and five other moons agree with the predictions of a resonance-locking tidal theory2, sustained by excitation of inertial waves inside the planet. The associated tidal expansion is only weakly sensitive to orbital distance, motivating a revision of the evolutionary history of Saturn’s moon system. In particular, it suggests that Titan formed much closer to Saturn and has migrated outward to its current position.

https://www.nature.com/articles/s41550-020-1120-5
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/17/2020 04:43 pm
Evidence for Volcanic Craters on Saturn's Moon Titan

http://spaceref.com/saturn/evidence-for-volcanic-craters-on-saturns-moon-titan.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/18/2020 07:09 am
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/18/2020 07:59 am
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260

From the horse's mouth: https://science.purdue.edu/xenon1t/?p=1474

The presentation in question: https://www.dropbox.com/s/vrq49tldjdfvnjh/shockley20200617.pdf?dl=0

Note this result is very much in tension with many other processes which should be directly influenced by axion production. A good (technical) contextualization is available in Resonàaances from a theoretician's point of view: http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html Bottom line: if this excess is solar axions, the astrophysical limits on axion cooling on red giants and white dwarves should get a major overhaul (which would come with lots of implications of their own). Meanwhile, unaccounted-for contamination in that pre-cutoff energy area is notoriously insidious in many experiments' analyses.

In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 06/18/2020 02:20 pm
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260

From the horse's mouth: https://science.purdue.edu/xenon1t/?p=1474

The presentation in question: https://www.dropbox.com/s/vrq49tldjdfvnjh/shockley20200617.pdf?dl=0

Note this result is very much in tension with many other processes which should be directly influenced by axion production. A good (technical) contextualization is available in Resonàaances from a theoretician's point of view: http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html Bottom line: if this excess is solar axions, the astrophysical limits on axion cooling on red giants and white dwarves should get a major overhaul (which would come with lots of implications of their own). Meanwhile, unaccounted-for contamination in that pre-cutoff energy area is notoriously insidious in many experiments' analyses.

In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)

Thank you for the additional pointers. Here a discussion by Jester (he is back!) about the pros and cons.
http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html

Please keep in mind his remark
Quote
How confident should we be that it's new physics? Experience has shown again and again that anomalies in new physics searches have, with a very large confidence, a mundane origin that does not involve exotic particles or interactions.

And
In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)

Sounds intriguing. How do we get a tour :) ?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/18/2020 04:07 pm
Thanks for the blog post by Jester.

Not sure this should be regarded as that ‘out there ‘ discovery as aren’t axions allowed for by the standard model.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/18/2020 04:15 pm
Astronomers detect regular rhythm of radio waves, with origins unknown

Quote
Signal from 500 million light years away is the first periodic pattern of radio bursts detected.

http://news.mit.edu/2020/astronomers-rhythm-radio-waves-0617
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/18/2020 04:55 pm
Did Galaxies Grow from Quantum Static?

Quote
A new test could determine whether large-scale cosmic structures have microscopic origins

https://www.scientificamerican.com/article/did-galaxies-grow-from-quantum-static/
Title: Re: Astronomy & Planetary Science Thread
Post by: trm14 on 06/18/2020 05:38 pm
Note this result is very much in tension with many other processes which should be directly influenced by axion production. A good (technical) contextualization is available in Resonàaances from a theoretician's point of view: http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html Bottom line: if this excess is solar axions, the astrophysical limits on axion cooling on red giants and white dwarves should get a major overhaul (which would come with lots of implications of their own). Meanwhile, unaccounted-for contamination in that pre-cutoff energy area is notoriously insidious in many experiments' analyses.

As (former) astrophysicist, I'm sceptical. Although "astrophysical limits reside in a different epistemological reality", red giant and white dwarf cooling limits are IMO on a more solid ground than the (wildly fluctuating) CMB limits on black holes that Jester refers to in a comment on his blog.
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/18/2020 07:29 pm
Thanks for the blog post by Jester.

Not sure this should be regarded as that ‘out there ‘ discovery as aren’t axions allowed for by the standard model.

I agree, I've coauthored axion searches myself and they're not subject to as many theoretical excursions as other better-known BSM particles, just "out of fashion" because hypothesized for a long time without results, and their signatures being in low-energy areas where few detectors are sensitive, with signals contaminated by usually overwhelming backgrounds.

In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)

Sounds intriguing. How do we get a tour :) ?

In-detector tours could be a bit dicey at the moment: you'd introduce backgrounds into the ultrapure water by just being immersed in it, plus you'd be uncomfortably close to high voltage and vacuum devices while in that water, a short distance away to a deeply cryogenic vessel ;)

There used to be different kinds of visitor tours in the Gran Sasso National Labs, be it through organized groups or individually if you knew some worker/scientist there (I was one, so was actually hosting them). Even pre-COVID, they'd been somewhat restricted lately due to safety issues after some local groups started being very aggressive against the facility due to (quite misguided) concerns about impacts to the water supply. Things might change for the better once the epidemic subsides in a few months though! There's a Google Street View tour in the meantime: https://www.google.it/maps/@42.4536018,13.5735141,2a,75y,114.86h,85.93t/data=!3m7!1e1!3m5!1sMlYGO6uL43-KhFD4XQ_MKg!2e0!3e5!7i13312!8i6656?hl=en
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 06/19/2020 09:22 am
Revisiting Shoemaker-Levy 9 impacts on Jupiter for Hubble's 30th birthday: https://illuminateduniverse.org/2020/06/18/guest-post-a-new-take-on-a-comets-impact-for-hubbles-30th/

Accompanying animation, by far the best rendition I've seen of this data so far:
https://www.youtube.com/watch?v=fq4PnAabL3Y
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 06/19/2020 06:24 pm
There used to be different kinds of visitor tours in the Gran Sasso National Labs, be it through organized groups or individually if you knew some worker/scientist there (I was one, so was actually hosting them). Even pre-COVID, they'd been somewhat restricted lately due to safety issues after some local groups started being very aggressive against the facility due to (quite misguided) concerns about impacts to the water supply. Things might change for the better once the epidemic subsides in a few months though! There's a Google Street View tour in the meantime: https://www.google.it/maps/@42.4536018,13.5735141,2a,75y,114.86h,85.93t/data=!3m7!1e1!3m5!1sMlYGO6uL43-KhFD4XQ_MKg!2e0!3e5!7i13312!8i6656?hl=en

Thank you for your insights and pointer to the Gran Sasso "inside-facility" Streetview. That is very cool to get a first impression! I found the Xenon1T detector. And a bunch of conference posters in the Streetview :)  I think it looks like an L-shaped facility in the tunnels. Is that correct?

While I have been fortunate enough to get private tours at several astronomy and telescope facilities at mountaintops here in the USA, I have never made it to CERN, Gran Sasso or Kamiokande (yet). Will enquire again after COVID ;) In the meantime, all stay safe.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/19/2020 10:07 pm
Coincidentally a new video about Axions.

https://youtu.be/VIFZzt_jB4Y
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/22/2020 11:33 am
Thank you for your insights and pointer to the Gran Sasso "inside-facility" Streetview. That is very cool to get a first impression! I found the Xenon1T detector. And a bunch of conference posters in the Streetview :)  I think it looks like an L-shaped facility in the tunnels. Is that correct?

My pleasure, I find these facilities fascinating too. The Laboratories are conformed as three 100-meter long, 18-meter wide/high cavities interconnected by smaller tunnels which are roughly parallel and just off to the side of the main 10-km highway tunnel, while the experimental halls are roughly perpendicular to it. XENON occupies about a third of the available floorspace in Hall B, the central one.

Myself, I've been to CERN, Gran Sasso *and* Kamioka (plus some other underground facilities such as SNOLab), but only once to professional observatories, in the Roque de los Muchachos of the Canary Islands. I guess I'm more of a (skywatching) mole than an eagle!

PS: Today is the opening day for Neutrino 2020 (due to be held in Chicago, but now online: https://indico.fnal.gov/event/43209/timetable/#20200622.detailed). Surely XENON will be spurring some interesting discussion, although I see no dedicated talk.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2020 05:00 pm
Talking of CERN.

Quote
The CERN Council has unanimously endorsed the idea of building a newer, larger circular supercollider, dubbed the Future Circular Collider (FCC). The group made the announcement on June 19. The move is the first step toward building a 100 TeV 100-kilometer circumference collider around Geneva. As part of the vote, the group approved the launch of a technical and financial feasibility study for the new collider.

https://phys.org/news/2020-06-cern-council-endorses-larger-supercollider.html

But not everyone thinks it’s a good idea.

https://www.scientificamerican.com/article/the-world-doesnt-need-a-new-gigantic-particle-collider/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/23/2020 04:54 pm
Evidence for a hot start and early ocean formation on Pluto

Abstract
Pluto is thought to possess a present-day ocean beneath a thick ice shell. It has generally been assumed that Pluto accreted from cold material and then later developed its ocean due to warming from radioactive decay; in this ‘cold start’ scenario, the ice shell would have experienced early compression and more recent extension. Here we compare thermal model simulations with geological observations from the New Horizons mission to suggest that Pluto was instead relatively hot when it formed, with an early subsurface ocean. Such a ‘hot start’ Pluto produces an early, rapid phase of extension, followed by a more prolonged extensional phase, which totals ~0.5% linear strain over the last 3.5 Gyr. The amount of second-phase extension is consistent with that inferred from extensional faults on Pluto; we suggest that an enigmatic ridge–trough system recently identified on Pluto is indicative of early extensional tectonics. A hot initial start can be achieved with the gravitational energy released during accretion if the final stage of Pluto’s accretion is rapid (<30 kyr). A fast final stage of growth is in agreement with models of the formation of Kuiper belt objects via gravitational collapse followed by pebble accretion, and implies that early oceans may have been common in the interiors of large Kuiper belt objects.

https://www.nature.com/articles/s41561-020-0595-0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/25/2020 06:29 pm
Neutrinos Reveal Final Secret of Sun’s Nuclear Fusion

Quote
The detection of particles produced in the sun’s core supports long-held theory about how our star is powered

https://www.scientificamerican.com/article/neutrinos-reveal-final-secret-of-suns-nuclear-fusion/
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/25/2020 11:19 pm
Neutrinos Reveal Final Secret of Sun’s Nuclear Fusion

Quote
The detection of particles produced in the sun’s core supports long-held theory about how our star is powered

https://www.scientificamerican.com/article/neutrinos-reveal-final-secret-of-suns-nuclear-fusion/ (https://www.scientificamerican.com/article/neutrinos-reveal-final-secret-of-suns-nuclear-fusion/)

Glad to see this has been picked up. Another write-up in Nature:

https://www.nature.com/articles/d41586-020-01908-2 (https://www.nature.com/articles/d41586-020-01908-2)

This is the experiment I "became of age" scientifically and professionally on, and I'm proud to have been an active Borexino collaboration member for 10 years next month. I've climbed up, down, across and through that huge tank more times than I can remember, installing some of its systems (by literally generously applying lots of vaseline on long cables that needed to be delicately inserted into tubes snaking to the sensitive guts of the detector), controlling its data-taking for dozens of shift weeks, and learning to love Italy in the process.

The main results and conclusions in my PhD thesis were focused on the hardware, simulations and techniques that directly laid the groundwork for this measurement to be possible, and I'm delighted it finally paid off, just months after I transitioned into industry to follow my other great passion, space.

We were just reminded by the emeritus professor who is one of the founding minds of Borexino, that at the time of its design and construction nobody, including most working in it (!) believed they could carry out the main goal of the experiment, i.e. measure most of the solar neutrino flux, which was too low energy for most other neutrino detectors, let alone the many "stretch goals" after that. I was lucky enough to witness, and give my infinitesimal contribution to, that refusal to give up and claw our way out of impossibility. CNO neutrino detection was just a pipedream even until very recently, but now also those have been unambiguously discerned, completing the full picture of nuclear heliophysics that was conceived in the 1930s - at least in the rough brushstrokes.

Feel free to inquire further with questions or comments, I'd be delighted to pass them along to the right person even if I don't know the answer myself :)
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/29/2020 04:05 pm
Black Hole Collision May Have Exploded with Light

Quote
When two black holes spiral around each other and ultimately collide, they send out ripples in space and time called gravitational waves. Because black holes do not give off light, these events are not expected to shine with any light waves, or electromagnetic radiation. But some theorists have come up with ways in which a black hole merger might explode with light. Now, for the first time, astronomers have seen evidence for one of these light-producing scenarios.

https://www.caltech.edu/about/news/black-hole-collision-may-have-exploded-light

Astronomers Discover 'Monster' Quasar from Early Universe

Quote
The discovery of the most massive quasar known in the early universe challenges current theories of supermassive black hole formation and growth during a time when the cosmos was still in its infancy.

https://uanews.arizona.edu/story/astronomers-discover-monster-quasar-early-universe
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2020 10:58 am
Betelgeuse fainter in the sub-millimetre too: an analysis of JCMT and APEX monitoring during the recent optical minimum

Betelgeuse is the nearest Red Supergiant star and it underwent an unusually deep minimum at optical wavelengths during its most recent pulsation cycle. We present submillimetre observations taken by the James Clerk Maxwell Telescope and Atacama Pathfinder Experiment over a time span of 13 years including the optical dimming. We find that Betelgeuse has also dimmed by \sim20\% at these longer wavelengths during this optical minimum. Using radiative-transfer models, we show that this is likely due to changes in the photosphere (luminosity) of the star as opposed to the surrounding dust as was previously suggested in the literature.

https://arxiv.org/abs/2006.09409

https://www.bbc.co.uk/news/science-environment-53218658
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2020 11:05 am
The possible disappearance of a massive star in the low-metallicity galaxy PHL 293B

ABSTRACT
We investigate a suspected very massive star in one of the most metal-poor dwarf galaxies, PHL 293B. Excitingly, we find the sudden disappearance of the stellar signatures from our 2019 spectra, in particular the broad H lines with P Cygni profiles that have been associated with a massive luminous blue variable (LBV) star. Such features are absent from our spectra obtained in 2019 with the Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observation and X-shooter instruments of the European Southern Observatory’s Very Large Telescope. We compute radiative transfer models using CMFGEN, which fit the observed spectrum of the LBV and are consistent with ground-based and archival Hubble Space Telescope photometry. Our models show that during 2001–2011, the LBV had a luminosity L* = 2.5–3.5 × 106 L⊙, a mass-loss rate M˙=0.005−0.020 M⊙
 yr−1, a wind velocity of 1000 km s−1, and effective and stellar temperatures of Teff = 6000–6800 and T* = 9500–15 000 K. These stellar properties indicate an eruptive state. We consider two main hypotheses for the absence of the broad emission components from the spectra obtained since 2011. One possibility is that we are seeing the end of an LBV eruption of a surviving star, with a mild drop in luminosity, a shift to hotter effective temperatures, and some dust obscuration. Alternatively, the LBV could have collapsed to a massive black hole without the production of a bright supernova.

https://academic.oup.com/mnras/article/496/2/1902/5863970

https://youtu.be/6Hcf7Ez-Rng
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/01/2020 04:48 pm
Quote
The Large Hadron Collider Beauty (LHCb) project has observed an exotic particle made up of four charm quarks for the first time.

The LHCb collaboration has observed a type of four-quark particle never seen before. The discovery, presented at a recent seminar at CERN and described in a paper published today is likely to be the first of a previously undiscovered class of particles never before seen by physicists.

https://phys.org/news/2020-07-exotic-particle-cern.html

Related paper:

https://arxiv.org/abs/2006.16957
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/06/2020 01:49 pm
A Gasless Gas Giant?

https://youtu.be/oB5WM4VSbu0
Title: Re: Astronomy & Planetary Science Thread
Post by: Orbiter on 07/06/2020 09:44 pm
Comet C/2020 F3 (NEOWISE) is visible just before sunrise in the northern hemisphere. It's currently shining as one of the brightest comets since Hale-Bopp in 1997 for northern hemisphere observers. Go check it out!
Title: Re: Astronomy & Planetary Science Thread
Post by: webdan on 07/07/2020 10:02 am
Comet C/2020 F3 (NEOWISE) is visible just before sunrise in the northern hemisphere. It's currently shining as one of the brightest comets since Hale-Bopp in 1997 for northern hemisphere observers. Go check it out!

Just did and spotted it within a minute. A pretty comet in binoculars. Neat how the tail has now started pointing towards the north as it circles around.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/07/2020 07:03 pm
Amateur astronomer discovers a brand new spot on Jupiter

https://www.digitaltrends.com/news/jupiter-clydes-spot-juno/
Title: Re: Astronomy & Planetary Science Thread
Post by: Orbiter on 07/08/2020 08:56 pm
Comet NEOWISE observed from the ISS.

https://www.youtube.com/watch?v=Yh1_wHdUx3Y
Title: Re: Astronomy & Planetary Science Thread
Post by: Arb on 07/08/2020 09:13 pm
Comet NEOWISE observed from the ISS.
Jump to 3:45 for first glimpse.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 07/10/2020 06:10 pm
Shamelessly plugging science i'm involved with;

Two Bizarre Brown Dwarfs Found With Citizen Scientists’ Help

https://www.nasa.gov/feature/goddard/2020/two-bizarre-brown-dwarfs-found-with-citizen-scientists-help

These two extremely low-metallicity brown dwarfs break the current atmospheric models and will be important in understanding how to correctly model gas giant atmospheres.

We've seen much lower-mass brown dwarfs before with solar metallicity, but before now the lowest with extremely sub-solar had been too warm to see the cloud-clearing physics.

Edit: Here's a better article,

http://pono.ucsd.edu/~adam/wordpress/blog/2020/07/12/cool-star-lab-contributes-to-discovery-of-extreme-metal-poor-brown-dwarfs/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/11/2020 11:09 am
Rapid geomagnetic changes inferred from Earth observations and numerical simulations

Abstract
Extreme variations in the direction of Earth’s magnetic field contain important information regarding the operation of the geodynamo. Paleomagnetic studies have reported rapid directional changes reaching 1° yr−1, although the observations are controversial and their relation to physical processes in Earth’s core unknown. Here we show excellent agreement between amplitudes and latitude ranges of extreme directional changes in a suite of geodynamo simulations and a recent observational field model spanning the past 100 kyrs. Remarkably, maximum rates of directional change reach  ~10° yr−1, typically during times of decreasing field strength, almost 100 times faster than current changes. Detailed analysis of the simulations and a simple analogue model indicate that extreme directional changes are associated with movement of reversed flux across the core surface. Our results demonstrate that such rapid variations are compatible with the physics of the dynamo process and suggest that future searches for rapid directional changes should focus on low latitudes.

https://www.nature.com/articles/s41467-020-16888-0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/12/2020 06:49 am
Evidence for a vast prograde stellar stream in the solar vicinity

Abstract
Massive dwarf galaxies that merge with the Milky Way on prograde orbits can be dragged into the disk plane before being completely disrupted. Such mergers can contribute to an accreted stellar disk and a dark matter disk. Here we present Nyx, a vast stellar stream in the vicinity of the Sun, which provides the first indication that such an event occurred in the Milky Way. We identify about 200 stars that have coherent radial and prograde motion in this stream using a catalogue of accreted stars built by applying deep learning methods to the Gaia data. Taken together with chemical abundance and orbital information, these results strongly favour the interpretation that Nyx is the remnant of a disrupted dwarf galaxy. Further justified by FIRE hydrodynamic simulations, we demonstrate that prograde streams like Nyx can be found in the disk plane of galaxies and identified using our methods.

https://www.nature.com/articles/s41550-020-1131-2
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/15/2020 08:23 am
Unexpected Circular Radio Objects at High Galactic Latitude

We have found an unexpected class of astronomical objects which have not previously been reported, in the Evolutionary Map of the Universe Pilot survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs about one arcmin diameter, and do not seem to correspond to any known type of object. We speculate that they may represent a spherical shock wave from an extra-galactic transient event, or the outflow, or a remnant, from a radio galaxy viewed end-on.

https://arxiv.org/abs/2006.14805
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 07/15/2020 03:15 pm
The Atacama Cosmology Telescope agrees with Planck, which increases the tension between CMB and local-universe Cepheid measures of Hubble's Constant.

New view of nature’s oldest light adds fresh twist to debate over universe’s age

https://www.princeton.edu/news/2020/07/15/new-view-natures-oldest-light-adds-fresh-twist-debate-over-universes-age

https://twitter.com/aiolasimone/status/1283402686755479559

On the other hand it doesn't see the possible hints of curvature Planck did, says the universe is very flat.

https://twitter.com/ermcalabrese/status/1283406366472798208
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/15/2020 06:41 pm
Star On The Run Probably Survived Going Partial Supernova

Quote
The unusual characteristics of a white dwarf have made astronomers think it went part way through a supernova explosion without going the whole way. If so, it would raise many questions about how such an event occurs, how common they are, and whether all partial supernovas stop at the same point.

https://www.iflscience.com/space/star-on-the-run-probably-survived-going-partial-supernova/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/18/2020 08:08 am
The Destruction and Recreation of the X-Ray Corona in a Changing-look Active Galactic Nucleus

Abstract
We present the drastic transformation of the X-ray properties of the active galactic nucleus (AGN) 1ES 1927+654, following a changing-look event. After the optical/ultraviolet outburst the power-law component, produced in the X-ray corona, disappeared, and the spectrum of 1ES 1927+65 instead became dominated by a blackbody component (kT ~ 80–120 eV). This implies that the X-ray corona, ubiquitously found in AGNs, was destroyed in the event. Our dense ~450 days long X-ray monitoring shows that the source is extremely variable in the X-ray band. On long timescales the source varies up to ~4 dex in ~100 days, while on short timescales up to ~2 dex in ~8 hr. The luminosity of the source is found to first show a strong dip down to $\sim {10}^{40}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$, and then a constant increase in luminosity to levels exceeding the pre-outburst level gsim300 days after the optical event detection, rising up asymptotically to $\sim 2\times {10}^{44}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$. As the X-ray luminosity of the source increases, the X-ray corona is recreated, and a very steep power-law component (Γ sime 3) reappears, and dominates the emission for 0.3–2 keV luminosities $\gtrsim {10}^{43.7}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$, ~300 days after the beginning of the event. We discuss possible origins of this event, and speculate that our observations could be explained by the interaction between the accretion flow and debris from a tidally disrupted star. Our results show that changing-look events can be associated with dramatic and rapid transformations of the innermost regions of accreting supermassive black holes.

https://iopscience.iop.org/article/10.3847/2041-8213/ab91a1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/21/2020 10:22 pm
Forming Betelgeuse from a Stellar Merger

https://aasnova.org/2020/06/22/featured-image-forming-betelgeuse-from-a-stellar-merger/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/22/2020 04:30 pm
Virtual Guided Tour La Silla Observatory:

https://youtu.be/KABNCxh9XOk
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/28/2020 04:47 pm
Quote
A car-sized asteroid discovered over the weekend made a close flyby of Earth today (July 28), passing our planet at a range that rivals the orbits of some high-flying satellites.

The asteroid 2020 OY4, which was first detected on Sunday (July 26), made its closest approach today at 1:31 a.m. EDT (0531 GMT) when it zipped by Earth at a speed of about 27,700 mph (44,600 km/h), according to the European Space Agency. The asteroid is just under 10 feet (3 meters) wide and posed no impact risk to Earth, but did approach the flight paths of geosynchronous satellites.

https://www.space.com/car-size-asteroid-2020-oy4-earth-flyby.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/29/2020 04:12 pm
Extended X-ray emission from the z=4.26 radio galaxy 4C 63.20

We report on deep Chandra X-ray Telescope imaging observations of 4C 63.20, one of the few known radio galaxies at z&gt;3.5. The X-ray counterpart is resolved into a core plus two off-nuclear sources that (combined) account for close to 30% of the total X-ray flux. Their morphology and orientation are consistent with a diffuse, lobe-like nature, albeit compact hotspots cannot be ruled out. The broadband spectral energy distribution of 4C 63.20 can be reproduced with a jet model where the majority of the radio flux can be ascribed to synchrotron emission from the hotspots, whereas the (non-nuclear) X-ray emission is produced via Inverse Compton (IC) off of Cosmic Microwave Background (CMB) photons within the extended lobes. This scenario is broadly consistent with the expectation from highly magnetized lobes in a hotter CMB, and supports the view that IC/CMB may quench less extreme radio lobes at high redshifts.

https://arxiv.org/abs/2007.10368
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/29/2020 04:25 pm
Quote
A recently deployed DARPA CubeSat seeks to demonstrate technology that could improve imaging of distant objects in space and allow powerful space telescopes to fit into small satellites. DARPA's Deformable Mirror (DeMi) CubeSat deployed from the International Space Station July 13, beginning the technology demonstration of a miniature space telescope with a small deformable mirror called a microelectromechanical systems (MEMS) mirror.

https://phys.org/news/2020-07-miniature-telescope-focuses-sharpening-view.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/04/2020 04:25 pm
Phosphorus-rich stars with unusual abundances are challenging theoretical predictions

Abstract
Almost all chemical elements have been made by nucleosynthetic reactions in various kind of stars and have been accumulated along our cosmic history. Among those elements, the origin of phosphorus is of extreme interest because it is known to be essential for life such as we know on Earth. However, current models of (Galactic) chemical evolution under-predict the phosphorus we observe in our Solar System. Here we report the discovery of 15 phosphorus-rich stars with unusual overabundances of O, Mg, Si, Al, and Ce. Phosphorus-rich stars likely inherit their peculiar chemistry from another nearby stellar source but their intriguing chemical abundance pattern challenge the present stellar nucleosynthesis theoretical predictions. Specific effects such as rotation or advanced nucleosynthesis in convective-reactive regions in massive stars represent the most promising alternatives to explain the existence of phosphorus-rich stars. The phosphorus-rich stars progenitors may significantly contribute to the phosphorus present on Earth today.

https://www.nature.com/articles/s41467-020-17649-9
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/04/2020 04:38 pm
Quote
The solar activity varies in 11-year cycles. After a few very passive years, the curve on solar activity turns to a very steep rise.

For a long time, researchers have believed that there is not much of interest going on in the Sun during the passive period, therefore not worth studying. Now this assumption is showed to be false by Juha Kallunki, Merja Tornikoski and Irene Björklund, researchers at Metsähovi Radio Observatory, in their peer-reviewed research article published in Solar Physics. This is the first time that astronomers are systematically studying the phenomena of the solar minimum.

https://www.aalto.fi/en/news/new-study-the-quiet-sun-is-much-more-active-than-we-thought
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/04/2020 06:59 pm
Quote
At the 40th ICHEP conference, the ATLAS and CMS experiments announced new results which show that the Higgs boson decays into two muons. The muon is a heavier copy of the electron, one of the elementary particles that constitute the matter content of the Universe. While electrons are classified as a first-generation particle, muons belong to the second generation. The physics process of the Higgs boson decaying into muons is a rare phenomenon as only about one Higgs boson in 5000 decays into muons. These new results have pivotal importance for fundamental physics because they indicate for the first time that the Higgs boson interacts with second-generation elementary particles.

https://phys.org/news/2020-08-cern-indications-rare-higgs-boson.html
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/08/2020 09:50 pm
https://youtu.be/LT8RuY-SW0g
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/12/2020 04:35 pm
ALMA Sees Most Distant Milky Way Look-alike:

https://youtu.be/8kW9LCr6_PA
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/13/2020 02:37 pm
S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit—S4711 on a 7.6 yr Orbit around Sgr A*

Abstract
We present high-pass filtered NACO and SINFONI images of the newly discovered stars S4711–S4715 between 2004 and 2016. Our deep H+K-band (SINFONI) and K-band (NACO) data show the S-cluster star S4711 on a highly eccentric trajectory around Sgr A* with an orbital period of 7.6 yr and a periapse distance of 144 au to the supermassive black hole (SMBH). S4711 is hereby the star with the shortest orbital period and the smallest mean distance to the SMBH during its orbit to date. The used high-pass filtered images are based on coadded data sets to improve the signal to noise. The spectroscopic SINFONI data let us determine detailed stellar properties of S4711 like the mass and the rotational velocity. The faint S-cluster star candidates, S4712–S4715, can be observed in a projected distance to Sgr A* of at least temporarily ≤120 mas. From these stars, S4714 is the most prominent, with an orbital period of 12 yr and an eccentricity of 0.985. The stars S4712–S4715 show similar properties, with magnitudes and stellar masses comparable to those of S4711. The MCMC simulations determine confidently precise uncertainties for the orbital elements of S62 and S4711–S4715. The presence of S4711 in addition to S55, S62, and the also newly found star S4714 implies a population of faint stars that can be found at distances to Sgr A* that are comparable to the size of our solar system. These short orbital time period stars in the dense cluster around the SMBH in the center of our Galaxy are perfect candidates to observe gravitational effects such as the periapse shift.

https://iopscience.iop.org/article/10.3847/1538-4357/ab9c1c
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/13/2020 04:39 pm
Snapped cable damages Arecibo observatory radio telescope:

https://youtu.be/4V3VCt24tkE
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/13/2020 10:02 pm
Cool Labs analysis has disproved all 6 recently announced Exomoon candidates:

https://youtu.be/OFMZBd04mOo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/16/2020 06:37 pm
Looks like they are hopeful of getting the funding to make the necessary repairs to Arecibo.

https://www.wired.com/story/the-iconic-arecibo-telescope-goes-quiet-after-major-damage/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/17/2020 04:49 pm
Gamma-ray heartbeat powered by the microquasar SS 433

Abstract
Microquasars, the local siblings of extragalactic quasars, are binary systems comprising a compact object and a companion star. By accreting matter from their companions, microquasars launch powerful winds and jets, influencing the interstellar environment around them. Steady gamma-ray emission is expected to rise from their central objects, or from interactions between their outflows and the surrounding medium. The latter prediction was recently confirmed with the detection of SS 433 at high (TeV) energies1. In this report, we analyse more than ten years of gigaelectronvolt gamma-ray data from the Fermi Gamma-ray Space Telescope on this source. Detailed scrutiny of the data reveal emission in the vicinity of SS 433, co-spatial with a gas enhancement, and hints of emission possibly associated with a terminal lobe of one of the jets. Both gamma-ray excesses are relatively far from the central binary, and the former shows evidence of a periodic variation at the precessional period of SS 433, linking it with the microquasar. This result challenges obvious interpretations and is unexpected from previously published theoretical models. It provides us with a chance to unveil the particle transport from SS 433 and to probe the structure of the magnetic field in its vicinity.

https://www.nature.com/articles/s41550-020-1164-6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/28/2020 04:26 pm
Strong constraints on thermal relic dark matter from Fermi-LAT observations of the Galactic Center

Quote
ABSTRACT
The extended excess toward the Galactic Center (GC) in gamma rays inferred from Fermi-LAT observations has been interpreted as being due to dark matter (DM) annihilation. Here, we perform new likelihood analyses of the GC and show that, when including templates for the stellar galactic and nuclear bulges, the GC shows no significant detection of a DM annihilation template, even after generous variations in the Galactic diffuse emission models and a wide range of DM halo profiles. We include Galactic diffuse emission models with combinations of three-dimensional inverse Compton maps, variations of interstellar gas maps, and a central source of electrons. For the DM profile, we include both spherical and ellipsoidal DM morphologies and a range of radial profiles from steep cusps to kiloparsec-sized cores, motivated in part by hydrodynamical simulations. Our derived upper limits on the dark matter annihilation flux place strong constraints on DM properties. In the case of the pure
b
-quark annihilation channel, our limits on the annihilation cross section are more stringent than those from the Milky Way dwarfs up to DM masses of approximately TeV and rule out the thermal relic cross section up to approximately 300 GeV. Better understanding of the DM profile, as well as the Fermi-LAT data at its highest energies, would further improve the sensitivity to DM properties.

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.043012
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/03/2020 06:42 pm
ESOcast 229:

https://youtu.be/KRqJoZapRcI
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/04/2020 06:36 pm
Cool Worlds - Why You’re Probably Not a Simulation

https://youtu.be/HA5YuwvJkpQ
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 09/08/2020 07:29 pm
Quote
Vera Rubin: Super telescope's giant camera spies broccoli
How do you test the new sensor for the world's largest digital camera? You take a picture of broccoli, of course.

This might sound bizarre but the intricate shapes found in the Romanesco version of this plant are a good check that you're capturing lots of detail.

https://www.bbc.com/news/science-environment-54066586
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/09/2020 04:30 pm
Quote
"Similarly to black holes, boson stars are predicted by general relativity and are able to grow to millions of solar masses and reach a very high compactness. The fact that they share these features with supermassive black holes led some authors to propose that some of the supermassive compact objects located at the center of galaxies could actually be boson stars."

So, in a new paper, Olivares and his team have calculated what a boson star might look like to one of our telescopes, and how that would differ from a direct image of an accreting black hole.

https://www.sciencealert.com/there-could-be-transparent-stars-made-of-bosons-masquerading-as-black-holes
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 09/11/2020 02:43 pm
There's currently some rumblings about a potentially significant press release on Monday the 14th from The Royal Astronomical Society.

https://twitter.com/AAS_Press/status/1303696305055830018

https://twitter.com/BBCStargazing/status/1304010713195839493

https://twitter.com/paulsanderson/status/1303535712231288832



I won't spoil it with the rumour but, if you can't contain yourself, people have noticed David Grinspoon has been tweeting a lot about a particular subject in the last few days...
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/11/2020 06:41 pm
Cool Worlds have a got a new video Monday wonder if it’s related as his community post appears to be a picture of Venus.

Hmmm....

https://twitter.com/paulsanderson/status/1303545061712429060
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/13/2020 11:44 am
There was an accidental leak of the story online so be careful. Though I believe it has now been removed.
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 09/13/2020 12:31 pm
There was an accidental leak of the story online so be careful. Though I believe it has now been removed.

Yeah, seems like an accidental (I should hope so, anyway) breaking of the embargo. The cat's out of the bag already.
Title: Re: Astronomy & Planetary Science Thread
Post by: Frogstar_Robot on 09/13/2020 12:56 pm
I have been searching for the "leak" but didn't find it. I am guessing it is some anomaly that could be caused by life, but probably isn't.

Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 09/13/2020 01:56 pm
There was an accidental leak of the story online so be careful. Though I believe it has now been removed.

Yeah, seems like an accidental (I should hope so, anyway) breaking of the embargo. The cat's out of the bag already.

Not the first time lately I've seen press teams upload a draft article thinking it isn't live if they don't link to it, but it can be searched for.

It's kind of reassuring secrets can't be kept for long, it's just not human nature.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 09/13/2020 02:03 pm
I have been searching for the "leak" but didn't find it. I am guessing it is some anomaly that could be caused by life, but probably isn't.

<REDACTED>


Well for a start there's an embargo which I doubt Chris or any of the rest of the NSF team would like us to break...
Title: Re: Astronomy & Planetary Science Thread
Post by: M.E.T. on 09/13/2020 02:06 pm
I have been searching for the "leak" but didn't find it. I am guessing it is some anomaly that could be caused by life, but probably isn't.


Well for a start there's an embargo which I doubt Chris or any of the rest of the NSF team would like us to break...

Well in that case I’ve removed the post. Suggest you do the same for the reply.

What does embargo actually mean though? Who puts such an “embargo” in place, and under what authority? The UN? The G8? The United Federation of Planets?

Anyway, post removed either way, but its all over the internet anyway.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/13/2020 02:10 pm
It took me all of 30 seconds to find it, the page has been removed but you only had to read the URL.
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 09/13/2020 02:10 pm
What does embargo actually mean though? Who puts such an “embargo” in place, and under what authority? The UN? The G8?

It's just being good sports and not stealing the thunder from the people who actually made the discovery/announcement. Additionally, embargos are used so that all media outlets can put out press releases and articles at the same time vs. some outlet cheesing it by publishing it early for the scoop. Such outlets usually lose their privileges from receiving future embargoed releases from the scientists so it's in the interest of both sides to honor the embargo.
Title: Re: Astronomy & Planetary Science Thread
Post by: M.E.T. on 09/13/2020 02:13 pm
What does embargo actually mean though? Who puts such an “embargo” in place, and under what authority? The UN? The G8?

It's just being good sports and not stealing the thunder from the people who actually made the discovery/announcement. Additionally, embargos are used so that all media outlets can put out press releases and articles at the same time vs. some outlet cheesing it by publishing it early for the scoop. Such outlets usually lose their privileges from receiving future embargoed releases from the scientists so it's in the interest of both sides to honor the embargo.

Ok, if that’s how they want it. Seems a bit silly in the age of the internet, but let’s play that game then.
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 09/13/2020 02:24 pm
Yeah, seems like an accidental (I should hope so, anyway) breaking of the embargo. The cat's out of the bag already.

Not the first time lately I've seen press teams upload a draft article thinking it isn't live if they don't link to it, but it can be searched for.

It's kind of reassuring secrets can't be kept for long, it's just not human nature.

Well, in this particular instance M.I.T. wasn't without blame, either. Understanding the difference between an unlisted and private video is hard...  ::)
Title: Re: Astronomy & Planetary Science Thread
Post by: Blackstar on 09/13/2020 02:27 pm
What does embargo actually mean though? Who puts such an “embargo” in place, and under what authority? The UN? The G8?

It's just being good sports and not stealing the thunder from the people who actually made the discovery/announcement. Additionally, embargos are used so that all media outlets can put out press releases and articles at the same time vs. some outlet cheesing it by publishing it early for the scoop. Such outlets usually lose their privileges from receiving future embargoed releases from the scientists so it's in the interest of both sides to honor the embargo.

Embargoes are actually gentleman's agreements--We will give you the information early, before we make it publicly available, in return for you agreeing to not make it public before that time. That gives a journalist time to read the report and write their article to have it ready for when the embargo is lifted. If a journalist violates an embargo, that is betraying the trust the organization had in them, and they won't be trusted with information again. (A number of years ago a blogger made a public statement about not honoring an embargo that he thought was stupid. You can imagine that a lot of organizations took note and decided they would not share embargoed information with that person under any circumstances.)

My organization regularly delivers embargoed reports to the sponsors (government agencies, like NASA) so that they can read them and be prepared to answer questions about them when the report goes public. This is so that they don't get questioned before they have even had a chance to read the report. Occasionally, we'll provide the embargoed report to a few science journalists a few hours before it goes public. It's all based upon professional trust. And it's part of an overall communications strategy, coordinating how the information gets released.

Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 09/13/2020 03:22 pm
What does embargo actually mean though? Who puts such an “embargo” in place, and under what authority? The UN? The G8?

It's just being good sports and not stealing the thunder from the people who actually made the discovery/announcement. Additionally, embargos are used so that all media outlets can put out press releases and articles at the same time vs. some outlet cheesing it by publishing it early for the scoop. Such outlets usually lose their privileges from receiving future embargoed releases from the scientists so it's in the interest of both sides to honor the embargo.

Embargoes are actually gentleman's agreements--We will give you the information early, before we make it publicly available, in return for you agreeing to not make it public before that time. That gives a journalist time to read the report and write their article to have it ready for when the embargo is lifted. If a journalist violates an embargo, that is betraying the trust the organization had in them, and they won't be trusted with information again. (A number of years ago a blogger made a public statement about not honoring an embargo that he thought was stupid. You can imagine that a lot of organizations took note and decided they would not share embargoed information with that person under any circumstances.)

My organization regularly delivers embargoed reports to the sponsors (government agencies, like NASA) so that they can read them and be prepared to answer questions about them when the report goes public. This is so that they don't get questioned before they have even had a chance to read the report. Occasionally, we'll provide the embargoed report to a few science journalists a few hours before it goes public. It's all based upon professional trust. And it's part of an overall communications strategy, coordinating how the information gets released.
Would this info already be known to the committees making decisions on something like the next Discovery or New Horizons?
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/13/2020 07:20 pm
[spoiler]Not directly related but good context.

https://arxiv.org/abs/1910.05224

https://www.liebertpub.com/doi/10.1089/ast.2017.1783[/spoiler]
Title: Re: Astronomy &amp; Planetary Science Thread
Post by: trm14 on 09/13/2020 08:28 pm
Would this info already be known to the committees making decisions on something like the next Discovery or New Horizons?

Some members might know it based on private conversations and such, but I don't think the committee knowing it a few days earlier would make  any difference anyway.

And since we're on subject of embargoes, a (tiny) rant: I very much dislike the (fairly common) habit of scientists, who are involved in the work, dropping teasers of embargoed stuff.  Personally, I don't really like the whole idea of embargoes that much, but if you have agreed to an embargo, I think you should respect it.
Title: Re: Astronomy & Planetary Science Thread
Post by: Frogstar_Robot on 09/13/2020 08:40 pm
I've read an article and watched a video about it, it does look pretty interesting!

I think the embargo probably expires midnight tonight, so expect a splash tomorrow.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 09/13/2020 08:54 pm
The embargo will almost certainly last til the announcement, which I think is about 11 am ET, 4 pm UK time?

I certainly think there's going to be some pushback on this, it's not a slam dunk, but interesting nevertheless.
Title: Re: Astronomy & Planetary Science Thread
Post by: Frogstar_Robot on 09/13/2020 09:34 pm
I don't know, the article was written yesterday in the past tense for publication tomorrow. So it describes things that will have happened. Only the media seem to know when the official announcement will be made.

As for extraordinary claims, yeah, solid proof is needed. "Bio-signature" is perhaps a little unequivical, I would prefer "bio-suggestive", since I am sure our knowledge of abiotic processes is not complete.
Title: Re: Astronomy & Planetary Science Thread
Post by: CJ on 09/14/2020 04:04 am
I've read the embargoed article, though I won't discuss it or provide info unless I see a NSF moderator say it's okay to do so.

On an utterly and entirely unrelated subject regarding planetary sciences, I wonder if it'd be possible to do a Venus sample return mission? Not from the surface (launching anything from there would actually be harder than launching from Earth) but an atmospheric sample, from around 60km up. I'm thinking that the easy way to do it is to skip an ascent vehicle or propulsion altogether. My inspiration is the Grand Teton Bolide of 1972; https://en.wikipedia.org/wiki/1972_Great_Daylight_Fireball

So, for a simple atmospheric sample return probe to Venus, build it very dense and strong (and somewhat large) and aerodynamic in a hypersonic regime. Place it on a hyperbolic trajectory to skim into Venus's atmosphere. Use a sampler scoop that avoids compression heating (akin to a pitot tube, with expansion cooling further into the sampling mechanism). It should be possible to arrange a trajectory that results in an earth-return. 
Title: Re: Astronomy & Planetary Science Thread
Post by: RotoSequence on 09/14/2020 04:36 am
I've read the embargoed article, though I won't discuss it or provide info unless I see a NSF moderator say it's okay to do so.

On an utterly and entirely unrelated subject regarding planetary sciences, I wonder if it'd be possible to do a Venus sample return mission? Not from the surface (launching anything from there would actually be harder than launching from Earth) but an atmospheric sample, from around 60km up. I'm thinking that the easy way to do it is to skip an ascent vehicle or propulsion altogether. My inspiration is the Grand Teton Bolide of 1972; https://en.wikipedia.org/wiki/1972_Great_Daylight_Fireball

So, for a simple atmospheric sample return probe to Venus, build it very dense and strong (and somewhat large) and aerodynamic in a hypersonic regime. Place it on a hyperbolic trajectory to skim into Venus's atmosphere. Use a sampler scoop that avoids compression heating (akin to a pitot tube, with expansion cooling further into the sampling mechanism). It should be possible to arrange a trajectory that results in an earth-return.

The steepest Planetary Protection Requirements are from other possible biospheres to our own. The only safe approach would be a distant orbit to be intercepted and sterilized in an orbital rendezvous first.
Title: Re: Astronomy & Planetary Science Thread
Post by: CJ on 09/14/2020 05:18 am
The steepest Planetary Protection Requirements are from other possible biospheres to our own. The only safe approach would be a distant orbit to be intercepted and sterilized in an orbital rendezvous first.

You are quite correct IMHO.

So, aerocapture into LEO.

My guess is they'd want to do an in-situ probe first; Venus entry then parachute descent. Find out more about the density and prevalence at various altitudes, plus some onboard analysis if they find anything. Perhaps even a probe that deploys a balloon for flotation. If they find something akin to an extemophile bacteria that can't live without high concentrations of sulfuric acid, that simplifies the planetary protection issue quite a bit.

Edit: Fixed the quote I broke.
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 09/14/2020 05:19 am
As a scientist who has published with the editorial-group-which-shall-not-be-named, I can tell you most professionald (in physics anyway) who aren't on the verge of retirement or directly benefited by the scheme have a pretty strong, negative opinion about current editorial practices, especially this group's - incluiding unilaterally-imposed embargoes.

Embargoes would make sense if they worked as you described above: a practice tailored to give an edge of advantage to journalists, in order for them to do their (paid) work and allow for a complete, thoroughly reviewed and multifaceted statement. As it currently stands, the actual scientists do much of that work, including cost-free (for the reader and editorial) dissemination and layman's terms interpretations - not to speak of the ridiculous issue of peer review itself, of course. The embargo is not in the general interest of neither the discovering group, nor journalists at large, nor of course the public. Neither does the scientific method work through strict withholding of information in order to prepare carefully-crafted press releases where the juicy points are either left out or barely treated with little context.

Of course, the academic meritocratic system being as dysfuncionally broken as it is at the moment, most can't wait to see it upended, but few can afford to take the lead. Thankfully better instant, worldwide comms are quickly leaving these archaic delights at esoterism in the XIX century bin where they belong.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 09/14/2020 10:41 am
https://twitter.com/RoyalAstroSoc/status/1305454796225351682
Title: Re: Astronomy & Planetary Science Thread
Post by: Welsh Dragon on 09/14/2020 11:56 am
As a scientist who has published with the editorial-group-which-shall-not-be-named, I can tell you most professionald (in physics anyway) who aren't on the verge of retirement or directly benefited by the scheme have a pretty strong, negative opinion about current editorial practices, especially this group's - incluiding unilaterally-imposed embargoes.
<snip>
As a scientist who has also published in high impact (neuroscience) journals, as well as someone who has received embargoed releases for comments before publication by national newspapers, I have never heard anybody complain about it. I'm not interested in a debate (I know physics has a much longer history of preprint servers), just saying your mileage may vary. I do agree that those in the field will generally know already, and that the model won't be long for this world probably.
Title: Re: Astronomy & Planetary Science Thread
Post by: FutureSpaceTourist on 09/14/2020 01:07 pm
I’ve started a new thread for discussion of today’s announcement about Venus:

https://forum.nasaspaceflight.com/index.php?topic=51942.0

Let’s wait until the announcement before posting comments in that thread
Title: Re: Astronomy & Planetary Science Thread
Post by: HVM on 09/14/2020 01:14 pm
I hope when the yellow press publish inevitable "Life Fond On Venus!" headlines they use art from C. S. Lewis Voyage to Venus book. (Good thing that evil rocket scientist not going to land Venus anytime soon, and kill frogs, or do other satanic things)
Title: Re: Astronomy & Planetary Science Thread
Post by: Svetoslav on 09/14/2020 01:39 pm
I hope when the yellow press publish inevitable "Life Fond On Venus!" headlines they use art from C. S. Lewis Voyage to Venus book. (Good thing that evil rocket scientist not going to land Venus anytime soon, and kill frogs, or do other satanic things)

They can simply use an image of Adam and Eve :) After all, the abovementioned book is about that.
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 09/14/2020 03:18 pm
As a scientist who has published with the editorial-group-which-shall-not-be-named, I can tell you most professionald (in physics anyway) who aren't on the verge of retirement or directly benefited by the scheme have a pretty strong, negative opinion about current editorial practices, especially this group's - incluiding unilaterally-imposed embargoes.
<snip>
As a scientist who has also published in high impact (neuroscience) journals, as well as someone who has received embargoed releases for comments before publication by national newspapers, I have never heard anybody complain about it. I'm not interested in a debate (I know physics has a much longer history of preprint servers), just saying your mileage may vary. I do agree that those in the field will generally know already, and that the model won't be long for this world probably.

I don't have even second-hand testimonials regarding biological sciences fields, so don't take this as debate against your experience - but when publishing in Nature all the embargo provided me and my group with was an uncomfortably long period of time in which we couldn't divulge our own result, even though it was public because of the arXiv preprint, and of course all of our colleagues were already on the loop and asking privately about it.

More recently last year, it meant an extremely awkward conference where, because of bad timing on both the publisher's and our side, we couldn't really show our main result since the journal was doing some internal process prior to publication, and early-career researches lost a valuable chance to promote themselves at an expensive, international event by showing a wonderful result they directly worked on, instead repeating stale years-old standard information.

In the latest case currently underway, it doesn't even make sense because the embargo applies for an already-presented important result - which is still embargoed because of the "methods" leading to the result, which in practice means the community *and* the public at large is aware of the achievement since June, while not being allowed to be told about the technicalities, basically having to trust us about it. This is clearly hindering for months both the technical talk that could derive from the result's novelty, stealing the full thunder of our achievement straight from us (yes, we could publish in a non-embargoed journal but as I mentioned there are lots of vested interests and prestige reasons by which only the biggest players can afford to lose the "oomph" gained by publishing in big-name journals) and rendering the whole embargo process moot. Another argument would be we needed to sit on the result until the journal was ready to publish, but that's not how the world works for people whose careers hang onto results that need at least 4 years of work to develop, and have to land a new job/graduate/move to another institution - which is how the academic world works for everyone but very few.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/24/2020 04:17 pm
M51-ULS-1b: The First Candidate for a Planet in an External Galaxy

Do external galaxies host planetary systems? Many lines of reasoning suggest that the answer must be 'yes'. In the foreseeable future, however, the question cannot be answered by the methods most successful in our own Galaxy. We report on a different approach which focuses on bright X-ray sources (XRSs). M51-ULS-1b is the first planet candidate to be found because it produces a full, short-lived eclipse of a bright XRS. M51-ULS-1b has a most probable radius slightly smaller than Saturn. It orbits one of the brightest XRSs in the external galaxy M51, the Whirlpool Galaxy, located 8.6 Megaparsecs from Earth. It is the first candidate for a planet in an external galaxy. The binary it orbits, M51-ULS-1, is young and massive. One of the binary components is a stellar remnant, either a neutron star (NS) or black hole (BH), and the other is a massive star. X-ray transits can now be used to discover more planets in external galaxies and also planets orbiting XRSs inside the Milky Way.

https://arxiv.org/abs/2009.08987
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/25/2020 11:23 am
Monitoring the Morphology of M87* in 2009–2017 with the Event Horizon Telescope

https://iopscience.iop.org/article/10.3847/1538-4357/abac0d
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/01/2020 04:33 pm
Paper:

https://www.eso.org/public/archives/releases/sciencepapers/eso2016/eso2016a.pdf

Related videos:

https://youtu.be/sMRDN85QmvQ

With the help ofESO’s Very Large Telescope (VLT), astronomers have found six galaxies lying around a supermassive black hole, the first time such a close grouping has been seen within the first billion years of the Universe. This artist’s impression shows the central black hole and the galaxies trapped in its gas web. The black hole, which together with the disc around it is known as quasar SDSS J103027.09+052455.0, shines brightly as it engulfs matter around it.

https://youtu.be/_-yx0292cdU

This video sequence zooms in on the web of the supermassive black hole found in the early Universe with six galaxies within it.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 10/12/2020 02:06 pm
ESOcast 231 Light:  Death by Spaghettification

https://youtu.be/UjPOtdbjsEs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/16/2020 07:34 pm
Quote
The red supergiant star Betelgeuse is smaller and much closer to Earth than previously believed, according to astronomers from the Australian National University, who have given a new data for when it will explode.

https://news.sky.com/story/scientists-figure-out-when-red-supergiant-betelgeuse-will-go-supernova-12105347
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 10/22/2020 03:17 am
It appears the Moon got jealous of all the attention on Venus.

https://twitter.com/Independent/status/1318998199818964993
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/26/2020 04:44 pm
This article covers the SOFIA announcement plus a related one about possible water in micro cold traps of which there appears to be thousands and a lot easier for any astronaut to access than the larger ones.

https://www.scientificamerican.com/article/water-found-in-sunlight-and-shadow-on-the-moon/
Title: Re: Astronomy & Planetary Science Thread
Post by: Bob Shaw on 10/26/2020 05:18 pm
During Apollo the astronauts sampled permanently shadowed areas but I'm unaware of any H20 being discovered. They reached in beneath boulders and rolled other ones over to sample material which had been shielded. I tend to think that the global spread of water may exist, but won't be easily exploited while high latitude shadowed areas might be reasonably easy.

Having said that, digging in frozen ground is *murder* here on Earth!

Perhaps we should be looking for a nice, fresh little impact crater like the ones we regularly see exposing ice on Mars? Such ice might well sublimate in a fairly short period, but the H20 vapour would surely show up as a dramatic transient hot reading visible from instruments on an ice-hunting orbiter.
 
Title: Re: Astronomy & Planetary Science Thread
Post by: ncb1397 on 10/26/2020 05:22 pm
During Apollo the astronauts sampled permanently shadowed areas but I'm unaware of any H20 being discovered. They reached in beneath boulders and rolled other ones over to sample material which had been shielded. I tend to think that the global spread of water may exist, but won't be easily exploited while high latitude shadowed areas might be reasonably easy.

Water was detected in the Apollo samples but it was assumed to be terrestrial contamination.

Quote
The moon rocks were analyzed for signs of water bound to minerals present in the rocks; while trace amounts of water were detected, these were assumed to be contamination from Earth, because the containers the rocks came back in had leaked.

“The isotopes of oxygen that exist on the moon are the same as those that exist on Earth, so it was difficult if not impossible to tell the difference between water from the moon and water from Earth,” said Larry Taylor of the University of Tennessee, Knoxville, who is a member of one of the NASA-built instrument teams for India’s Chandrayaan-1 satellite and has studied the moon since the Apollo missions.
https://sservi.nasa.gov/articles/its-official-water-found-on-the-moon/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/26/2020 08:09 pm
How Big Can a Black Hole Get?

https://youtu.be/p7AWIpZX1yg
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/27/2020 04:28 pm
Quote
NASA scientists identified a molecule in Titan’s atmosphere that has never been detected in any other atmosphere. In fact, many chemists have probably barely heard of it or know how to pronounce it: cyclopropenylidene, or C3H2. Scientists say that this simple carbon-based molecule may be a precursor to more complex compounds that could form or feed possible life on Titan.

https://www.nasa.gov/feature/goddard/2020/nasa-scientists-discover-a-weird-molecule-in-titan-s-atmosphere
Title: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2020 07:10 am
Could this event give a clue to the source of some FRBs:

https://youtu.be/CiGj-gtygDU

Related article:

https://news.mit.edu/2020/ultrabright-radio-flashes-detection-1104
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2020 10:38 am
Quote
Every 26 seconds, the Earth shakes. Not a lot — certainly not enough that you’d feel it — but just enough that seismologists on multiple continents get a measurable little “blip” on their detectors. But even though this pulse has been observed for decades, researchers don’t agree on what’s causing it. The mystery surrounding the phenomenon even has its own XKCD web comic.

https://www.discovermagazine.com/environment/the-earth-is-pulsating-every-26-seconds-and-seismologists-dont-agree-why
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2020 11:11 am
Modelling the atmosphere of lava planet K2-141b: implications for low- and high-resolution spectroscopy

ABSTRACT
Transit searches have uncovered Earth-size planets orbiting so close to their host star that their surface should be molten, so-called lava planets. We present idealized simulations of the atmosphere of lava planet K2-141b and calculate the return flow of material via circulation in the magma ocean. We then compare how pure Na, SiO, or SiO2 atmospheres would impact future observations. The more volatile Na atmosphere is thickest followed by SiO and SiO2, as expected. Despite its low vapour pressure, we find that a SiO2 atmosphere is easier to observe via transit spectroscopy due to its greater scale height near the day–night terminator and the planetary radial velocity and acceleration are very high, facilitating high dispersion spectroscopy. The special geometry that arises from very small orbits allows for a wide range of limb observations for K2-141b. After determining the magma ocean depth, we infer that the ocean circulation required for SiO steady-state flow is only 10−4 m s−1, while the equivalent return flow for Na is several orders of magnitude greater. This suggests that a steady-state Na atmosphere cannot be sustained and that the surface will evolve over time.

https://academic.oup.com/mnras/article/499/4/4605/5948140
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2020 02:46 pm
It seems even ‘old’ Red Dwarfs are bad to be near if you’re life on a nearby planet.

The High-Energy Radiation Environment Around a 10 Gyr M Dwarf: Habitable at Last?

High levels of X-ray and UV activity on young M dwarfs may drive rapid atmospheric escape on temperate, terrestrial planets orbiting within the liquid water habitable zone. However, secondary atmospheres on planets orbiting older, less active M dwarfs may be stable and present more promising candidates for biomarker searches. We present new HST and Chandra observations of Barnard's Star (GJ 699), a 10 Gyr old M3.5 dwarf, acquired as part of the Mega-MUSCLES program. Despite the old age and long rotation period of Barnard's star, we observe two FUV (δ130 ≈ 5000s; E130 ≈ 1029.5 erg each) and one X-ray (EX ≈ 1029.2 erg) flares, and estimate a high-energy flare duty cycle (defined here as the fraction of the time the star is in a flare state) of ∼ 25\%. A 5 A - 10 μm SED of GJ 699 is created and used to evaluate the atmospheric stability of a hypothetical, unmagnetized terrestrial planet in the habitable zone (rHZ ∼ 0.1 AU). Both thermal and non-thermal escape modeling indicate (1) the quiescent stellar XUV flux does not lead to strong atmospheric escape: atmospheric heating rates are comparable to periods of high solar activity on modern Earth, and (2) the flare environment could drive the atmosphere into a hydrodynamic loss regime at the observed flare duty cycle: sustained exposure to the flare environment of GJ 699 results in the loss of ≈ 87 Earth atmospheres Gyr−1 through thermal processes and ≈ 3 Earth atmospheres Gyr−1 through ion loss processes, respectively. These results suggest that if rocky planet atmospheres can survive the initial ∼ 5 Gyr of high stellar activity, or if a second generation atmosphere can be formed or acquired, the flare duty cycle may be the controlling stellar parameter for the stability of Earth-like atmospheres around old M stars.

https://arxiv.org/abs/2009.01259
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2020 04:40 pm
Perhaps 2020 is not the best year to be publishing this:

Risks for Life on Habitable Planets from Superflares of Their Host Stars

Abstract
We explore some of the ramifications arising from superflares on the evolutionary history of Earth, other planets in the solar system, and exoplanets. We propose that the most powerful superflares can serve as plausible drivers of extinction events, and that their periodicity corresponds to certain patterns in the terrestrial fossil diversity record. On the other hand, weaker superflares may play a positive role in enabling the origin of life through the formation of key organic compounds. Superflares could also prove to be quite detrimental to the evolution of complex life on present-day Mars and exoplanets in the habitable zone of M- and K-dwarfs. We conclude that the risk posed by superflares has not been sufficiently appreciated, and that humanity might potentially witness a superflare event in the next $\sim {10}^{3}$ years, leading to devastating economic and technological losses. In light of the many uncertainties and assumptions associated with our analysis, we recommend that these results should be viewed with due caution.

https://iopscience.iop.org/article/10.3847/1538-4357/aa8e96/meta
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 11/05/2020 07:28 pm
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260

From the horse's mouth: https://science.purdue.edu/xenon1t/?p=1474

The presentation in question: https://www.dropbox.com/s/vrq49tldjdfvnjh/shockley20200617.pdf?dl=0

Note this result is very much in tension with many other processes which should be directly influenced by axion production. A good (technical) contextualization is available in Resonàaances from a theoretician's point of view: http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html Bottom line: if this excess is solar axions, the astrophysical limits on axion cooling on red giants and white dwarves should get a major overhaul (which would come with lots of implications of their own). Meanwhile, unaccounted-for contamination in that pre-cutoff energy area is notoriously insidious in many experiments' analyses.

In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)

Solar Axions Cannot Explain the XENON1T Excess
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.131804

Quote
We argue that the interpretation in terms of solar axions of the recent XENON1T excess is not tenable when confronted with astrophysical observations of stellar evolution. We discuss the reasons why the emission of a flux of solar axions sufficiently intense to explain the anomalous data would radically alter the distribution of certain type of stars in the color-magnitude diagram in the first place and would also clash with a certain number of other astrophysical observables. Quantitatively, the significance of the discrepancy ranges from 3.3σ for the rate of period change of pulsating white dwarfs and exceeds 19σ for the R parameter and for M_I,TRGB.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/06/2020 10:02 am
The article below explains the above in more straightforward manner and includes quotes from the team.

https://phys.org/news/2020-11-solar-axions-xenon1t-excess.html
Title: Astronomy & Planetary Science Thread
Post by: Star One on 11/10/2020 10:55 am
Direct Radio Discovery of a Cold Brown Dwarf

Abstract
Magnetospheric processes seen in gas giants such as aurorae and circularly polarized cyclotron maser radio emission have been detected from some brown dwarfs. However, previous radio observations targeted known brown dwarfs discovered via their infrared emission. Here we report the discovery of BDR J1750+3809, a circularly polarized radio source detected around 144 MHz with the Low-Frequency Array (LOFAR) telescope. Follow-up near-infrared photometry and spectroscopy show that BDR J1750+3809 is a cold methane dwarf of spectral type T6.5 ± 1 at a distance of ${65}_{-8}^{+9}\,\mathrm{pc}$. The quasi-quiescent radio spectral luminosity of BDR J1750+3809 is ≈5 × 1015 erg s−1 Hz−1, which is over two orders of magnitude larger than that of the known population of comparable spectral type. This could be due to a preferential geometric alignment or an electrodynamic interaction with a close companion. In addition, as the emission is expected to occur close to the electron gyrofrequency, the magnetic field strength at the emitter site in BDR J1750+3809 is B gsim 25 G, which is comparable to planetary-scale magnetic fields. Our discovery suggests that low-frequency radio surveys can be employed to discover substellar objects that are too cold to be detected in infrared surveys.

https://iopscience.iop.org/article/10.3847/2041-8213/abc256

https://www.eurekalert.org/pub_releases/2020-11/aouf-mtc110920.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2020 10:57 am
A Terrestrial-mass Rogue Planet Candidate Detected in the Shortest-timescale Microlensing Event

Abstract
Some low-mass planets are expected to be ejected from their parent planetary systems during early stages of planetary system formation. According to planet formation theories, such as the core accretion theory, typical masses of ejected planets should be between 0.3 and 1.0 M ⊕. Although in practice such objects do not emit any light, they may be detected using gravitational microlensing via their light-bending gravity. Microlensing events due to terrestrial-mass rogue planets are expected to have extremely small angular Einstein radii (lesssim1 μas) and extremely short timescales (lesssim0.1 day). Here, we present the discovery of the shortest-timescale microlensing event, OGLE-2016-BLG-1928, identified to date (${t}_{{\rm{E}}}\approx 0.0288\,\mathrm{day}=41.5\,\mathrm{minutes}$). Thanks to the detection of finite-source effects in the light curve of the event, we were able to measure the angular Einstein radius of the lens ${\theta }_{{\rm{E}}}=0.842\pm 0.064$ μas, making the event the most extreme short-timescale microlens discovered to date. Depending on its unknown distance, the lens may be a Mars- to Earth-mass object, with the former possibility favored by the Gaia proper motion measurement of the source. The planet may be orbiting a star but we rule out the presence of stellar companions up to the projected distance of ~8.0 au from the planet. Our discovery demonstrates that terrestrial-mass free-floating planets can be detected and characterized using microlensing.

https://iopscience.iop.org/article/10.3847/2041-8213/abbfad
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2020 11:04 am
Born eccentric: Constraints on Jupiter and Saturn’s pre-instability orbits

Abstract
An episode of dynamical instability is thought to have sculpted the orbital structure of the outer solar system. When modeling this instability, a key constraint comes from Jupiter’s fifth eccentric mode (quantified by its amplitude
), which is an important driver of the solar system’s secular evolution. Starting from commonly-assumed near-circular orbits, the present-day giant planets’ architecture lies at the limit of numerically generated systems, and
 is rarely excited to its true value. Here we perform a dynamical analysis of a large batch of artificially triggered instabilities, and test a variety of configurations for the giant planets’ primordial orbits. In addition to more standard setups, and motivated by the results of modern hydrodynamical simulations of the giant planets’ evolution within the primordial gaseous disk, we consider the possibility that Jupiter and Saturn emerged from the nebular gas locked in 2:1 resonance with non-zero eccentricities. We show that, in such a scenario, the modern Jupiter–Saturn system represents a typical simulation outcome, and
 is commonly matched. Furthermore, we show that Uranus and Neptune’s final orbits are determined by a combination of the mass in the primordial Kuiper belt and that of an ejected ice giant.

https://www.sciencedirect.com/science/article/abs/pii/S0019103520304644?via%3Dihub
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2020 02:48 pm
The Blanco DECam bulge survey. I. The survey description and early results

ABSTRACT
The Blanco Dark Energy Camera (DECam) Bulge survey is a Vera Rubin Observatory (LSST) pathfinder imaging survey, spanning ∼200 deg2 of the Southern Galactic bulge, −2° &lt; b &lt; −13° and −11° &lt; l &lt; +11°. We have employed the CTIO-4 m telescope and the DECam to image a contiguous ∼200 deg2 region of the relatively less reddened Southern Galactic bulge, in SDSS u  + Pan-STARRSgrizy. Optical photometry with its large colour baseline will be used to investigate the age and metallicity distributions of the major structures of the bulge. Included in the survey footprint are 26 globular clusters imaged in all passbands. Over much of the bulge, we have Gaia DR2 matching astrometry to i ∼ 18, deep enough to reach the faint end of the red clump. This paper provides the background, scientific case, and description of the survey. We present an array of new reddening-corrected colour–magnitude diagrams that span the extent of Southern Galactic bulge. We argue that a population of massive stars in the blue loop evolutionary phase, proposed to lie in the bulge, are instead at ∼2 kpc from the Sun and likely red clump giants in the old disc. A bright red clump near (l, b) = (+ 8°, −4°) may be a feature in the foreground disc, or related to the long bar reported in earlier work. We also report the first map of the blue horizontal branch population spanning the Blanco DECam Bulge Survey field of regard, and our data do not confirm the reality of a number of proposed globular clusters in the bulge.

https://academic.oup.com/mnras/article/499/2/2340/5893795

Blanco DECam Bulge Survey (BDBS) II: project performance, data analysis, and early science results

ABSTRACT
The Blanco DECam Bulge Survey (BDBS) imaged more than 200 sq deg of the Southern Galactic bulge using the ugrizY filters of the Dark Energy Camera, and produced point spread function photometry of approximately 250 million unique sources. In this paper, we present details regarding the construction and collation of survey catalogues, and also discuss the adopted calibration and dereddening procedures. Early science results are presented with a particular emphasis on the bulge metallicity distribution function and globular clusters. A key result is the strong correlation (σ ∼ 0.2 dex) between (u − i)o and [Fe/H] for bulge red clump giants. We utilized this relation to find that interior bulge fields may be well described by simple closed box enrichment models, but fields exterior to b ∼ −6° seem to require a secondary metal-poor component. Applying scaled versions of the closed box model to the outer bulge fields is shown to significantly reduce the strengths of any additional metal-poor components when compared to Gaussian mixture models. Additional results include: a confirmation that the u band splits the subgiant branch in M22 as a function of metallicity, the detection of possible extratidal stars along the orbits of M 22 and FSR 1758, and additional evidence that NGC 6569 may have a small but discrete He spread, as evidenced by red clump luminosity variations in the reddest bands. We do not confirm previous claims that FSR 1758 is part of a larger extended structure.

https://academic.oup.com/mnras/article/499/2/2357/5900983
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/13/2020 10:39 am
Quote
Massive explosions of energy happening thousands of light-years from Earth may have left traces in our planet's biology and geology, according to new research.

https://www.sciencedaily.com/releases/2020/11/201111144400.htm
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/16/2020 04:07 pm
With things like this maybe indicating that the Earth is something of a fluke, the same with the Sun being a rare beast in star terms. Perhaps in this time span there really isn’t much else intelligent life wise in the Milky Way.

Radiogenic Heating and its Influence on Rocky Planet Dynamos and Habitability

The thermal evolution of rocky planets on geological timescales (Gyr) depends on the heat input from the long-lived radiogenic elements potassium, thorium, and uranium. Concentrations of the latter two in rocky planet mantles are likely to vary by up to an order of magnitude between different planetary systems because Th and U, like other heavy r-process elements, are produced by rare stellar processes. Here we discuss the effects of these variations on the thermal evolution of an Earth-size planet, using a 1D parameterized convection model. Assuming Th and U abundances consistent with geochemical models of the Bulk Silicate Earth based on chondritic meteorites, we find that Earth had just enough radiogenic heating to maintain a persistent dynamo. According to this model, Earth-like planets of stars with higher abundances of heavy r-process elements, indicated by the relative abundance of europium in their spectra, are likely to have lacked a dynamo for a significant fraction of their lifetimes, with potentially negative consequences for hosting a biosphere. Because the qualitative outcomes of our 1D model are strongly dependent on the treatment of viscosity, further investigations using fully 3D convection models are desirable.

https://arxiv.org/abs/2011.04791
Title: Re: Astronomy Thread
Post by: leovinus on 11/16/2020 07:37 pm
Scientists Planning Now for Asteroid Flyby a Decade Away (https://www.jpl.nasa.gov/news/news.php?feature=7390)

On April 13, 2029, a speck of light will streak across the sky, getting brighter and faster. At one point it will travel more than the width of the full Moon within a minute and it will get as bright as the stars in the Little Dipper. But it won't be a satellite or an airplane - it will be a 1,100-foot-wide (340-meter-wide) near-Earth asteroid called 99942 Apophis that will cruise harmlessly by Earth, about 19,000 miles (31,000 kilometers) above the surface. That's within the distance that some of our spacecraft that orbit Earth.

The international asteroid research community couldn't be more excited.

This week at the 2019 Planetary Defense Conference in College Park, Maryland, scientists are gathering to discuss observation plans and science opportunities for the celestial event still a decade away. During a session on April 30, scientists will discuss everything from how to observe the event to hypothetical missions we could send out to the asteroid.

Planning is continuing. As we do not have a good thread to follow Apophis science, experiments and planning (just drama and movies :) ) I put a link to the recent workshop on Nov 4-6 here.

Apophis T–9 Years: Knowledge Opportunities for the Science of Planetary Defense (https://www.hou.usra.edu/meetings/apophis2020/pdf/apophis2020_program.htm)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/17/2020 11:16 am
Quote
The asteroid – 2020 VT4 – is estimated to be between 16 and 36 feet (5-11 meters). It skimmed the top of our atmosphere on Friday, November 13, 2020. Astronomers spotted it one day later.

https://earthsky.org/space/asteroid-2020-vt4-skimmed-atmosphere-fri-nov-13-2020
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/17/2020 04:06 pm
The Quantitative Comparison Between the Neuronal Network and the Cosmic Web

We investigate the similarities between two of the most challenging and complex systems in Nature: the network of neuronal cells in the human brain, and the cosmic network of galaxies. We explore the structural, morphological, network properties and the memory capacity of these two fascinating systems, with a quantitative approach. In order to have an homogeneous analysis of both systems, our procedure does not consider the true neural connectivity but an approximation of it, based on simple proximity. The tantalizing degree of similarity that our analysis exposes seems to suggest that the self-organization of both complex systems is likely being shaped by similar principles of network dynamics, despite the radically different scales and processes at play.

https://www.frontiersin.org/articles/10.3389/fphy.2020.525731/full
Title: Re: Astronomy & Planetary Science Thread
Post by: bolun on 11/18/2020 10:54 am
ESA CELEBRATES 25TH ANNIVERSARY OF THE INFRARED SPACE OBSERVATORY WITH NEW DATA ARCHIVE INTERFACE (https://sci.esa.int/web/iso/-/esa-celebrates-25th-anniversary-of-the-infrared-space-observatory-with-new-data-archive-interface) (ISO)

Quote
Today, ESA is celebrating the 25th anniversary of the launch of the Infrared Space Observatory, ISO, with a brand new interface to the mission's unique legacy archive.

Quote
Among its scientific highlights, ISO detected the presence of water vapour throughout the Universe, including in star-forming regions, in the vicinity of stars at the end of their lives, in the atmospheres of planets in our Solar System and in the Orion Nebula. Several new molecules, such as hydrogen fluoride, were also discovered in space for the first time using ISO's sensitive instruments. ISO also discovered substantial amounts of cosmic dust in the vast empty space between galaxies, and was used to determine that the powerful source of infrared light in the nearest ultra-luminous infrared galaxy, Arp 220, is an outburst of star formation in that galaxy.

Quote
Today, on the occasion of ISO's 25th launch anniversary, ESA announces a brand new interface to the ISO data archive. The mission's complete data sets are now available through the faster, lighter, and user-friendly web interface at http://archives.esac.esa.int/nida.

Image credit: ESA/ISO
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 11/18/2020 02:18 pm
The Ultimately Large Telescope -- what kind of facility do we need to detect Population III stars?
https://arxiv.org/abs/2007.02946

Quote
In this paper, we investigate the basic properties of the Ultimately Large Telescope, a facility that can detect Population III star formation regions at high redshift. Observations will take place in the near-infrared and therefore a moon-based facility is proposed

The  Ultimately Large Telescope, henceforth dubbed the "ULT", on the Moon.
Also discussed at https://www.theregister.com/2020/11/18/moon_ultimate_telescope/
Quote
Astronomers have revived a decade-old idea that was abandoned by NASA: a 100-metre-wide liquid-mirror telescope on the Moon to study the stars.
Title: Re: Astronomy & Planetary Science Thread
Post by: libra on 11/18/2020 03:45 pm
The Ultimately Large Telescope -- what kind of facility do we need to detect Population III stars?
https://arxiv.org/abs/2007.02946

Quote
In this paper, we investigate the basic properties of the Ultimately Large Telescope, a facility that can detect Population III star formation regions at high redshift. Observations will take place in the near-infrared and therefore a moon-based facility is proposed

The  Ultimately Large Telescope, henceforth dubbed the "ULT", on the Moon.
Also discussed at https://www.theregister.com/2020/11/18/moon_ultimate_telescope/
Quote
Astronomers have revived a decade-old idea that was abandoned by NASA: a 100-metre-wide liquid-mirror telescope on the Moon to study the stars.

(just day dreaming because of the above post)

There was another path forward, to get the ultimate, giant lunar borne space telescope...

Imagine, if we had build Labeyrie hypertelescope on the Moon, using KH-7 GAMBIT-1 and KH-8 GAMBIT-3 48-inch mirrors.
For the record, the NRO orbited 92 spysats with such mirrors between 1963 and 1984. Now that was a mass produced, lightweight, spaceborne mirror...
And the supporting bus was an Agena, thus a rocket stage. Tweak it a little so that it can land itself on the Moon carrying a GAMBIT 48 inch mirror. Rinse, repeat, lands scores of Agenas with mirrors, side by side on a flat lunar plain - until Labeyrie hypertelescope become a reality... 
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/19/2020 10:42 am
There’s a link to the video in the press release.

CSIRO research vessel Investigator films meteor break up over ocean

https://www.csiro.au/en/News/News-releases/2020/CSIRO-research-vessel-Investigator-films-meteor-break-up-over-ocean
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/20/2020 10:31 am
I can only find a newspaper link for this news.

Quote
A "fossil galaxy" has been found hidden inside of our Milky Way.

The discovery of the long-dead galaxy could change our understanding of the history of the Milky Way, and how it became the vast web of stars that surrounds us today.

The fossil, known as Heracles, is thought to have collided with the Milky Way 10 billion years ago, when our galaxy was still at a very young age.

https://www.google.co.uk/amp/s/www.independent.co.uk/life-style/gadgets-and-tech/milky-way-galaxy-fossil-heracles-space-b1758973.html%3famp
Title: Re: Astronomy & Planetary Science Thread
Post by: Robert Hags on 11/26/2020 11:41 am
Hello there.
Recently I faced with information that astronomers proposed a return to the idea of ​​an extremely large telescope on the Moon. Such a tool was first proposed in 2008. However, then the understanding of what can be done in terms of studying the earliest stars was too vague, and the project of a telescope installed on the moon remained at the level of an idea. It will have a mirror with a diameter of 100 meters and will be able to work autonomously from the surface of the moon, receiving energy through solar panels. The telescope will transmit the collected data through a satellite in lunar orbit. The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror. So do you think whether it would be a good idea to settle a telescope on the Moon or not?
Title: Re: Astronomy & Planetary Science Thread
Post by: DreamyPickle on 11/26/2020 12:15 pm
Recently I faced with information that astronomers proposed a return to the idea of ​​an extremely large telescope on the Moon. Such a tool was first proposed in 2008. However, then the understanding of what can be done in terms of studying the earliest stars was too vague, and the project of a telescope installed on the moon remained at the level of an idea. It will have a mirror with a diameter of 100 meters and will be able to work autonomously from the surface of the moon, receiving energy through solar panels. The telescope will transmit the collected data through a satellite in lunar orbit. The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror.

This would require large-scale construction on the Moon far outside what is currently possible. Even if the SpaceX Starship is successful constructing a 100-meter-sized anything would be a huge challenge.

Are there no smaller proposals, for example something that could be delivered and assembled in a single mission? Even a Hubble-sized telescope on the Moon would be difficult to build.
Title: Re: Astronomy & Planetary Science Thread
Post by: Frogstar_Robot on 11/26/2020 01:20 pm
The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror. So do you think whether it would be a good idea to settle a telescope on the Moon or not?

I'm not sure why you would use a liquid mirror, what is the advantage? How is it steered?

I'm also not clear about the advantage of it being on the Moon. If you have the technology to build a 100m mirror on the Moon, seems like you can do a similar thing in orbit.
Title: Re: Astronomy & Planetary Science Thread
Post by: RonM on 11/26/2020 01:32 pm
The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror. So do you think whether it would be a good idea to settle a telescope on the Moon or not?

I'm not sure why you would use a liquid mirror, what is the advantage? How is it steered?

I'm also not clear about the advantage of it being on the Moon. If you have the technology to build a 100m mirror on the Moon, seems like you can do a similar thing in orbit.

A liquid mirror is easier to build. Fill a cylindrical tank with mercury and rotate it. The combination of rotation and gravity gives it the correct shape. Won't work in orbit. The disadvantage is you can't steer it.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 11/26/2020 01:53 pm
Generally speaking it makes more sense to build a radio telescope array on the Moon first.  Less complex, more benefit.
Title: Re: Astronomy & Planetary Science Thread
Post by: Frogstar_Robot on 11/26/2020 02:01 pm
The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror. So do you think whether it would be a good idea to settle a telescope on the Moon or not?

I'm not sure why you would use a liquid mirror, what is the advantage? How is it steered?

I'm also not clear about the advantage of it being on the Moon. If you have the technology to build a 100m mirror on the Moon, seems like you can do a similar thing in orbit.

A liquid mirror is easier to build. Fill a cylindrical tank with mercury and rotate it. The combination of rotation and gravity gives it the correct shape. Won't work in orbit. The disadvantage is you can't steer it.

I did some reading on the web... Wikipedia says "The greatest advantage of a liquid mirror is its small cost, about 1% of a conventional telescope mirror. This cuts down the cost of the entire telescope at least 95%". So that is very significant saving on Earth, but for a lunar telescope transport costs might outweigh manufacturing cost, and mercury is heavy.

But mercury would freeze on the Moon anyway (unless the tank was heated), the proposal [1] for a lunar version would use ionic salts.

I wasn't suggesting putting a liquid mirror in orbit, for obvious reasons, but others have. I was thinking of a more conventional segmented mirror.

If you need a 100m tank, I think you would have to transport that in sections and assemble on site. In that case, transporting mirror segments might be more cost-effective.

But I think the tail is wagging the dog here. We don't really want a zenith telescope on the Moon. But if we want a cheap telescope, it has to be sited there, and limited to zenith.

[1] https://phys.org/news/2020-11-texas-astronomers-revive-idea-ultimately.html
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 11/26/2020 02:29 pm
The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror. So do you think whether it would be a good idea to settle a telescope on the Moon or not?

I'm not sure why you would use a liquid mirror, what is the advantage? How is it steered?

I'm also not clear about the advantage of it being on the Moon. If you have the technology to build a 100m mirror on the Moon, seems like you can do a similar thing in orbit.

A liquid mirror is easier to build. Fill a cylindrical tank with mercury and rotate it. The combination of rotation and gravity gives it the correct shape. Won't work in orbit. The disadvantage is you can't steer it.

But mercury would freeze on the Moon anyway (unless the tank was heated), the proposal [1] for a lunar version would use ionic salts.

Indeed. Less than 10 posts ago, some more background articles were posted around the salt-based liquid and Ultimately Large Telescope (ULT) ideas on the Moon.
https://forum.nasaspaceflight.com/index.php?topic=42108.msg2155590#msg2155590
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/26/2020 07:01 pm
Regarding a lunar crater radio telescope:

https://youtu.be/8c8tG1sAK78
Title: Re: Astronomy & Planetary Science Thread
Post by: Robert Hags on 11/27/2020 07:02 am
Recently I faced with information that astronomers proposed a return to the idea of ​​an extremely large telescope on the Moon. Such a tool was first proposed in 2008. However, then the understanding of what can be done in terms of studying the earliest stars was too vague, and the project of a telescope installed on the moon remained at the level of an idea. It will have a mirror with a diameter of 100 meters and will be able to work autonomously from the surface of the moon, receiving energy through solar panels. The telescope will transmit the collected data through a satellite in lunar orbit. The telescope mirror itself will be a large bowl filled with a liquid like mercury. This bowl will rotate continuously so that the liquid surface has the correct paraboloid shape and can act as a mirror.

This would require large-scale construction on the Moon far outside what is currently possible. Even if the SpaceX Starship is successful constructing a 100-meter-sized anything would be a huge challenge.

Are there no smaller proposals, for example something that could be delivered and assembled in a single mission? Even a Hubble-sized telescope on the Moon would be difficult to build.

Hey. Sorry I didn't reply you yesterday. As for me, no structures on the moon or in general in space can be built in one delivery of resources. It seems to me that this is possible only when sending several flights and then collecting them at the place of destantion. By the way, the International Space Station was also not ready to be put into operation in one day. So the only option is to ship the telescope in parts.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/27/2020 08:13 am
Quote
Over the last 15 years, a Japanese radio astronomy project, VERA, has been gathering data. Using a technique called interferometry, VERA gathered data from telescopes across Japan and combined them with data from other existing projects to create what is essentially the most accurate map of the Milky Way yet.

By pinpointing the location and velocity of around 99 specific points in our galaxy, VERA has concluded that the supermassive black hole Sagittarius A, at the center of our galaxy, is actually 25,800 light-years from Earth -- almost 2,000 light-years closer than what we previously believed.

https://www.cnet.com/news/earth-just-got-2000-light-years-closer-to-milky-ways-supermassive-black-hole/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/28/2020 07:55 am
New Extraction of the Cosmic Birefringence from the Planck 2018 Polarization Data

ABSTRACT
We search for evidence of parity-violating physics in the Planck 2018 polarization data and report on a new measurement of the cosmic birefringence angle
β
. The previous measurements are limited by the systematic uncertainty in the absolute polarization angles of the Planck detectors. We mitigate this systematic uncertainty completely by simultaneously determining
β
 and the angle miscalibration using the observed cross-correlation of the
E
- and
B
-mode polarization of the cosmic microwave background and the Galactic foreground emission. We show that the systematic errors are effectively mitigated and achieve a factor-of-2 smaller uncertainty than the previous measurement, finding
β
=
0.35
±
0.14


deg
 (68% C.L.), which excludes
β
=
0
 at 99.2% C.L. This corresponds to the statistical significance of
2.4
σ
.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.221301

Scientists Detect Hints of Strange New Physics in The Universe's Background Radiation

https://www.sciencealert.com/a-twist-in-the-background-radiation-of-the-universe-hints-at-new-physics
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/28/2020 10:22 am
Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun

Abstract
For most of their existence, stars are fuelled by the fusion of hydrogen into helium. Fusion proceeds via two processes that are well understood theoretically: the proton–proton (pp) chain and the carbon–nitrogen–oxygen (CNO) cycle1,2. Neutrinos that are emitted along such fusion processes in the solar core are the only direct probe of the deep interior of the Sun. A complete spectroscopic study of neutrinos from the pp chain, which produces about 99 per cent of the solar energy, has been performed previously3; however, there has been no reported experimental evidence of the CNO cycle. Here we report the direct observation, with a high statistical significance, of neutrinos produced in the CNO cycle in the Sun. This experimental evidence was obtained using the highly radiopure, large-volume, liquid-scintillator detector of Borexino, an experiment located at the underground Laboratori Nazionali del Gran Sasso in Italy. The main experimental challenge was to identify the excess signal—only a few counts per day above the background per 100 tonnes of target—that is attributed to interactions of the CNO neutrinos. Advances in the thermal stabilization of the detector over the last five years enabled us to develop a method to constrain the rate of bismuth-210 contaminating the scintillator. In the CNO cycle, the fusion of hydrogen is catalysed by carbon, nitrogen and oxygen, and so its rate—as well as the flux of emitted CNO neutrinos—depends directly on the abundance of these elements in the solar core. This result therefore paves the way towards a direct measurement of the solar metallicity using CNO neutrinos. Our findings quantify the relative contribution of CNO fusion in the Sun to be of the order of 1 per cent; however, in massive stars, this is the dominant process of energy production. This work provides experimental evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe.

https://www.nature.com/articles/s41586-020-2934-0
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/03/2020 06:54 pm
Quote
In September 2019, my colleague Anna Kapinska gave a presentation showing interesting objects she’d found while browsing our new radio astronomical data. She had started noticing very weird shapes she couldn’t fit easily to any known type of object.

Among them, labelled by Anna as WTF?, was a picture of a ghostly circle of radio emission, hanging out in space like a cosmic smoke-ring. None of us had ever seen anything like it before, and we had no idea what it was. A few days later, our colleague Emil Lenc found a second one, even more spooky than Anna’s.

https://theconversation.com/wtf-newly-discovered-ghostly-circles-in-the-sky-cant-be-explained-by-current-theories-and-astronomers-are-excited-142812

Unexpected Circular Radio Objects at High Galactic Latitude

We have found a class of circular radio objects in the Evolutionary Map of the Universe Pilot Survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs, about one arcmin diameter, that are unlike other objects previously reported in the literature. We explore several possible mechanisms that might cause these objects, but none seems to be a compelling explanation.

https://arxiv.org/abs/2006.14805
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/05/2020 10:39 am
Deep Future Climate on Earth: effects of tectonics, rotation rate, and insolation

Abstract

We explore two possible Earth climate scenarios, 200 and 250 million years into the future, using knowledge of the evolution of plate tectonics, solar luminosity, and rotation rate. In one scenario, a supercontinent forms at low latitudes, whereas in the other it forms at high northerly latitudes with an antarctic subcontinent remaining at the south pole. The climates between these two end points are quite stark, with differences in mean surface temperatures approaching 4 degrees. The fractional habitability (mean surface temperatures remaining between 0$&lt;$T$&lt;$100$^\circ$ year round) on land is shown to differ as much as 40\% between the two simulations. These results demonstrate the need to consider alternative boundary conditions when simulating Earth-like exoplanetary climates.

https://www.essoar.org/doi/10.1002/essoar.10501348.1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/05/2020 11:19 am
P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

Abstract
The recently discovered object P/2019 LD2 (by the Asteroid Terrestrial-impact Last Alert System) was initially thought to be a Jupiter Trojan asteroid, until dynamical studies and the appearance of persistent cometary activity revealed that this object is actually an active Centaur. However, the dynamical history, thermal environment, and impact of such environments on the activity of 2019 LD2 are poorly understood. Here we conduct dynamical simulations to constrain its orbital history and resulting thermal environment over the past 3000 yr. We find that 2019 LD2 is currently in the vicinity of a dynamical "Gateway" that facilitates the majority of transitions from the Centaur population into the Jupiter Family of Comets (JFC population). Our calculations show that it is unlikely to have spent significant amounts of time in the inner solar system, suggesting that its nucleus is relatively pristine in terms of physical, chemical, and thermal processing through its history. This could explain its relatively high level of distant activity as a recently activated primordial body. Finally, we find that the median frequency of transition from the Gateway population into the JFC population varies from once every ~3 yr to less than once every 70 yr, if 2019 LD2's nucleus is ~1 km in radius or greater than 3 km in radius. Forward modeling of 2019 LD2 shows that it will transition into the JFC population in 2063, representing the first known opportunity to observe the evolution of an active Centaur nucleus as it experiences this population-defining transition.

https://iopscience.iop.org/article/10.3847/2041-8213/abc888
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/05/2020 02:04 pm
The MKID Exoplanet Camera for Subaru SCExAO

Abstract
We present the MKID Exoplanet Camera (MEC), a z through J band (800–1400 nm) integral field spectrograph located behind The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) at the Subaru Telescope on Maunakea that utilizes Microwave Kinetic Inductance Detectors (MKIDs) as the enabling technology for high contrast imaging. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. The read noise free, fast time domain information attainable by MKIDs allows for the direct probing of fast speckle fluctuations that currently limit the performance of most high contrast imaging systems on the ground and will help MEC achieve its ultimate goal of reaching contrasts of 10−7 at 2 λ/D. Here we outline the instrument details of MEC including the hardware, firmware, and data reduction and analysis pipeline. We then discuss MEC's current on-sky performance and end with future upgrades and plans.

https://iopscience.iop.org/article/10.1088/1538-3873/abc60f
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/05/2020 02:20 pm
[Submitted on 28 Oct 2020]
A case of simultaneous star and planet formation


While it is widely accepted that planets are formed in protoplanetary disks, there is still much debate on when this process happens. In a few cases protoplanets have been directly imaged, but for the vast majority of systems, disk gaps and cavities -- seen especially in dust continuum observations -- have been the strongest evidence of recent or on-going planet formation. We present ALMA observations of a nearly edge-on (i=75) disk containing a giant gap seen in dust but not in 12CO gas. Inside the gap, the molecular gas has a warm (100 K) component coinciding in position with a tentative free-free emission excess observed with the VLA. Using 1D hydrodynamic models, we find the structure of the gap is consistent with being carved by a planet with 4-70 MJup. The coincidence of free-free emission inside the planet-carved gap points to the planet being very young and/or still accreting. In addition, the 12CO observations reveal low-velocity large scale filaments aligned with the disk major axis and velocity coherent with the disk gas that we interpret as ongoing gas infall from the local ISM. This system appears to be an interesting case where both a star (from the environment and the disk) and a planet (from the disk) are growing in tandem.

https://arxiv.org/abs/2010.15135
Title: Astronomy & Planetary Science Thread
Post by: Star One on 12/12/2020 08:55 pm
Cool Worlds and a breakthrough in the hunt for Exomoons:

https://youtu.be/voLPBjqTSao

A surprisingly personal video.  His only Exomoon candidate so far does pass in his new method of finding Exomoons. Indicating that it probably is the biggest moon ever discovered.

The Exomoon Corridor: Half of all exomoons exhibit TTV frequencies within a narrow window due to aliasing

Exomoons are expected to produce potentially detectable transit timing variations (TTVs) upon their parent planet. Unfortunately, distinguishing moon-induced TTVs from other sources, in particular planet-planet interactions, has severely impeded its usefulness as a tool for identifying exomoon candidates. A key feature of exomoon TTVs is that they will always be undersampled, due to the simple fact that we can only observe the TTVs once per transit/planetary period. We show that it is possible to analytically express the aliased TTV periodicity as a function of planet and moon period. Further, we show that inverting an aliased TTV period back to a true moon period is fraught with hundreds of harmonic modes. However, a unique aspect of these TTV aliases is that they are predicted to occur at consistently short periods, irrespective of what model one assumes for the underlying moon population. Specifically, 50% of all exomoons are expected to induce TTVs with a period between 2 to 4 cycles, a range that planet-planet interactions rarely manifest at. This provides an exciting and simple tool for quickly identifying exomoons candidates and brings the TTV method back to the fore as an exomoon hunting strategy. Applying this method to the candidate, Kepler-1625b i, reveals that its TTV periodicity centers around the median period expected for exomoons.

https://arxiv.org/abs/2012.00764
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/15/2020 02:17 pm
Quote
Astronomers are still searching for a hypothetical “Planet Nine” in the distant reaches of our solar system, but an exoplanet 336 light years from Earth is looking more and more like the Planet Nine of its star system .

Planet Nine, potentially 10 times the size of Earth and orbiting far beyond Neptune in a highly eccentric orbit about the sun, was proposed in 2012 to explain perturbations in the orbits of dwarf planets just beyond Neptune’s orbit, so-called detached Kuiper Belt objects. It has yet to be found, if it exists.

A similarly weird extrasolar planet was discovered far from the star HD 106906 in 2013, the only such wide-separation planet known. While much heavier than the predicted mass of Planet Nine — perhaps 11 times the mass of Jupiter, or 3,500 times the mass of Earth — it, too, was sitting in a very unexpected location, far above the dust plane of the planetary system and tilted at an angle of about 21 degrees.

https://news.berkeley.edu/2020/12/10/exoplanet-around-distant-star-resembles-our-reputed-planet-nine/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/20/2020 09:02 pm
The search for radio emission from the exoplanetary systems 55 Cancri, υ Andromedae, and τ Boötis using LOFAR beam-formed observations

Observing planetary auroral radio emission is the most promising method to detect exoplanetary magnetic fields, the knowledge of which will provide valuable insights into the planet's interior structure, atmospheric escape, and habitability. We present LOFAR-LBA circularly polarized beamformed observations of the exoplanetary systems 55 Cancri, υ Andromedae, and τ Boötis. We tentatively detect circularly polarized bursty emission from the τ Boötis system in the range 14-21 MHz with a flux density of ∼890 mJy and with a significance of ∼3σ. For this detection, no signal is seen in the OFF-beams, and we do not find any potential causes which might cause false positives. We also tentatively detect slowly variable circularly polarized emission from τ Boötis in the range 21-30 MHz with a flux density of ∼400 mJy and with a statistical significance of >8σ. The slow emission is structured in the time-frequency plane and shows an excess in the ON-beam with respect to the two simultaneous OFF-beams. Close examination casts some doubts on the reality of the slowly varying signal. We discuss in detail all the arguments for and against an actual detection. Furthermore, a ∼2σ marginal signal is found from the υ Andromedae system and no signal is detected from the 55 Cancri system. Assuming the detected signals are real, we discuss their potential origin. Their source probably is the τ Bootis planetary system, and a possible explanation is radio emission from the exoplanet τ Bootis b via the cyclotron maser mechanism. Assuming a planetary origin, we derived limits for the planetary polar surface magnetic field strength, finding values compatible with theoretical predictions. Further low-frequency observations are required to confirm this possible first detection of an exoplanetary radio signal. [Abridged]

https://arxiv.org/abs/2012.07926
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/20/2020 09:07 pm
Related thread from one of the papers authors.

https://twitter.com/Astro_journey/status/1339231323995713537
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/28/2020 03:19 pm
Exploring Primordial Black Holes from the Multiverse with Optical Telescopes

Primordial black holes (PBHs) are a viable candidate for dark matter if the PBH masses are in the currently unconstrained "sublunar" mass range. We revisit the possibility that PBHs were produced by nucleation of false vacuum bubbles during inflation. We show that this scenario can produce a population of PBHs that simultaneously accounts for all dark matter, explains the candidate event in Subaru Hyper Suprime-Cam (HSC) data, and contains both heavy black holes as observed by LIGO and very heavy seeds of supermassive black holes. We demonstrate with numerical studies that future observations of HSC, as well as other optical surveys, such as LSST, will be able to provide a definitive test for this generic PBH formation mechanism if it is the dominant source of dark matter.

https://arxiv.org/abs/2001.09160

Quote
Why was the HSC indispensable in this research? The HSC has a unique capability to image the entire Andromeda galaxy every few minutes. If a black hole passes through the line of sight to one of the stars, the black hole’s gravity bends the light rays and makes the star appear brighter than before for a short period of time. The duration of the star’s brightening tells the astronomers the mass of the black hole. With HSC observations, one can simultaneously observe one hundred million stars, casting a wide net for primordial black holes that may be crossing one of the lines of sight.

The first HSC observations have already reported a very intriguing candidate event consistent with a PBH from the “multiverse,” with a black hole mass comparable to the mass of the Moon. Encouraged by this first sign, and guided by the new theoretical understanding, the team is conducting a new round of observations to extend the search and to provide a definitive test of whether PBHs from the multiverse scenario can account for all dark matter.

https://scienmag.com/primordial-black-holes-and-the-search-for-dark-matter-from-the-multiverse/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/29/2020 08:57 am
Looks like they accidentally proved one aspect of the MOND theory.

Testing the Strong Equivalence Principle: Detection of the External Field Effect in Rotationally Supported Galaxies

Abstract
The strong equivalence principle (SEP) distinguishes general relativity (GR) from other viable theories of gravity. The SEP demands that the internal dynamics of a self-gravitating system under freefall in an external gravitational field should not depend on the external field strength. We test the SEP by investigating the external field effect (EFE) in Milgromian dynamics (MOND), proposed as an alternative to dark matter in interpreting galactic kinematics. We report a detection of this EFE using galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) sample together with estimates of the large-scale external gravitational field from an all-sky galaxy catalog. Our detection is threefold: (1) the EFE is individually detected at 8σ to 11σ in "golden" galaxies subjected to exceptionally strong external fields, while it is not detected in exceptionally isolated galaxies, (2) the EFE is statistically detected at more than 4σ from a blind test of 153 SPARC rotating galaxies, giving a mean value of the external field consistent with an independent estimate from the galaxies' environments, and (3) we detect a systematic downward trend in the weak gravity part of the radial acceleration relation at the right acceleration predicted by the EFE of the MOND modified gravity. Tidal effects from neighboring galaxies in the Λ cold dark matter (CDM) context are not strong enough to explain these phenomena. They are not predicted by existing ΛCDM models of galaxy formation and evolution, adding a new small-scale challenge to the ΛCDM paradigm. Our results point to a breakdown of the SEP, supporting modified gravity theories beyond GR.

https://iopscience.iop.org/article/10.3847/1538-4357/abbb96
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/02/2021 03:49 pm
Quote
Planet Earth's success in staying habitable for billions of years is partly down to luck, according to a new study.

https://news.sky.com/story/earth-has-been-lucky-to-support-life-for-3-billion-years-study-says-12177251
Title: Re: Astronomy & Planetary Science Thread
Post by: Dizzy_RHESSI on 01/04/2021 02:41 pm
Looks like they accidentally proved one aspect of the MOND theory.


The paper hardly "accidental" given the author list. What they found is certainly model dependent, they find evidence for an external field effect under the assumption of a MOND framework. That's not the same as proving an external field definitely exists, which would mean disproving general relativity. They don't actually consult any standard model simulations of galaxies in this paper, so I'll take their claim that CDM cannot explain this with a pinch of salt for now. These claims usually take a few years to be understood in the literature.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/04/2021 09:18 pm
Looks like they accidentally proved one aspect of the MOND theory.


The paper hardly "accidental" given the author list. What they found is certainly model dependent, they find evidence for an external field effect under the assumption of a MOND framework. That's not the same as proving an external field definitely exists, which would mean disproving general relativity. They don't actually consult any standard model simulations of galaxies in this paper, so I'll take their claim that CDM cannot explain this with a pinch of salt for now. These claims usually take a few years to be understood in the literature.
I said accidental as that wasn’t what they were looking for when they set out.
Title: Re: Astronomy & Planetary Science Thread
Post by: tpw2 on 01/04/2021 10:08 pm

The paper hardly "accidental" given the author list. What they found is certainly model dependent, they find evidence for an external field effect under the assumption of a MOND framework. That's not the same as proving an external field definitely exists, which would mean disproving general relativity. They don't actually consult any standard model simulations of galaxies in this paper, so I'll take their claim that CDM cannot explain this with a pinch of salt for now. These claims usually take a few years to be understood in the literature.
I said accidental as that wasn’t what they were looking for when they set out.

It seems to me that they found exactly what they were looking for, so I don't understand what you mean by accidental.

The people behind the paper are MOND proponents and McGaugh in particular is probably the most well-known (observational) MOND researcher currently. Indeed, when I saw the title, I was pretty sure that McGaugh had to be involved.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/05/2021 10:27 am

The paper hardly "accidental" given the author list. What they found is certainly model dependent, they find evidence for an external field effect under the assumption of a MOND framework. That's not the same as proving an external field definitely exists, which would mean disproving general relativity. They don't actually consult any standard model simulations of galaxies in this paper, so I'll take their claim that CDM cannot explain this with a pinch of salt for now. These claims usually take a few years to be understood in the literature.
I said accidental as that wasn’t what they were looking for when they set out.

It seems to me that they found exactly what they were looking for, so I don't understand what you mean by accidental.

The people behind the paper are MOND proponents and McGaugh in particular is probably the most well-known (observational) MOND researcher currently. Indeed, when I saw the title, I was pretty sure that McGaugh had to be involved.
I am reflecting how it was reported in the article I first saw the news of this paper.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/05/2021 10:31 am
591 High-velocity Stars in the Galactic Halo Selected from LAMOST DR7 and Gaia DR2

Abstract
In this paper, we report 591 high-velocity star candidates (HiVelSCs) selected from over 10 million spectra of Data Release 7 (DR7) of the Large Sky Area Multi-object Fiber Spectroscopic Telescope and the second Gaia data release, with three-dimensional velocities in the Galactic rest frame larger than 445 km s−1. We show that at least 43 HiVelSCs are unbound to the Galaxy with escape probabilities larger than 50%, and this number decreases to eight if the possible parallax zero-point error is corrected. Most of these HiVelSCs are metal-poor and slightly α-enhanced inner halo stars. Only 14% of them have [Fe/H] > −1, which may be the metal-rich "in situ" stars in the halo formed in the initial collapse of the Milky Way or metal-rich stars formed in the disk or bulge but kinematically heated. The low ratio of 14% implies that the bulk of the stellar halo was formed from the accretion and tidal disruption of satellite galaxies. In addition, HiVelSCs on retrograde orbits have slightly lower metallicities on average compared with those on prograde orbits; meanwhile, metal-poor HiVelSCs with [Fe/H] < −1 have an even faster mean retrograde velocity compared with metal-rich HiVelSCs. To investigate the origins of HiVelSCs, we perform orbit integrations and divide them into four types, i.e., hypervelocity stars, hyper-runaway stars, runaway stars and fast halo stars. A catalog for these 591 HiVelSCs, including radial velocities, atmospheric parameters, Gaia astrometric parameters, spatial positions, and velocities, etc., is available in the China-VO PaperData Repository at doi:10.12149/101038.

https://iopscience.iop.org/article/10.3847/1538-4365/abc16e

Source: https://www.universetoday.com/149461/astronomers-discover-hundreds-of-high-velocity-stars-many-on-their-way-out-of-the-milky-way/amp/
Title: Astronomy & Planetary Science Thread
Post by: Star One on 01/05/2021 10:40 am
Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM

We present an expanded sample of 75 Milky Way Cepheids with Hubble Space Telescope (HST) photometry and Gaia EDR3 parallaxes which we use to recalibrate the extragalactic distance ladder and refine the determination of the Hubble constant. All HST observations were obtained with the same instrument (WFC3) and filters (F555W, F814W, F160W) used for imaging of extragalactic Cepheids in Type Ia supernova (SN Ia) hosts. The HST observations used the WFC3 spatial scanning mode to mitigate saturation and reduce pixel-to-pixel calibration errors, reaching a mean photometric error of 5 millimags per observation. We use new Gaia EDR3 parallaxes, vastly improved since DR2, and the Period-Luminosity (PL) relation of these Cepheids to simultaneously calibrate the extragalactic distance ladder and to refine the determination of the Gaia EDR3 parallax offset. The resulting geometric calibration of Cepheid luminosities has 1.0% precision, better than any alternative geometric anchor. Applied to the calibration of SNe~Ia, it results in a measurement of the Hubble constant of 73.0 +/- 1.4 km/sec/Mpc, in good agreement with conclusions based on earlier Gaia data releases. We also find the slope of the Cepheid PL relation in the Milky Way, and the metallicity dependence of its zeropoint, to be in good agreement with the mean values derived from other galaxies. In combination with the best complementary sources of Cepheid calibration, we reach 1.8% precision and find H_0=73.2 +/- 1.3 km/sec/Mpc, a 4.2 sigma difference with the prediction from Planck CMB observations under LambdaCDM. We expect to reach ~1.3% precision in the near term from an expanded sample of ~40 SNe Ia in Cepheid hosts.

https://arxiv.org/abs/2012.08534

Source: https://www.universetoday.com/149482/astronomers-improve-their-distance-scale-for-the-universe-unfortunately-it-doesnt-resolve-the-crisis-in-cosmology/amp/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/08/2021 10:18 am
A look at the Proxima Centauri system:

https://youtu.be/LPwB5unPRuo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/12/2021 02:28 pm
ALMA captures distant colliding galaxy dying out as it loses the ability to form stars

Quote
Galaxies begin to “die” when they stop forming stars, but until now astronomers had never clearly glimpsed the start of this process in a far-away galaxy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have seen a galaxy ejecting nearly half of its star-forming gas. This ejection is happening at a startling rate, equivalent to 10 000 Suns-worth of gas a year — the galaxy is rapidly losing its fuel to make new stars. The team believes that this spectacular event was triggered by a collision with another galaxy, which could lead astronomers to rethink how galaxies stop bringing new stars to life.

https://www.almaobservatory.org/en/press-releases/alma-captures-distant-colliding-galaxy-dying-out-as-it-loses-the-ability-to-form-stars/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/12/2021 09:17 pm
Swift, TESS Catch Eruptions From an Active Galaxy:

https://youtu.be/4esMWZZAaA8
Title: Astronomy & Planetary Science Thread
Post by: Star One on 01/20/2021 09:09 am
Solar activity reconstructed over a millennium

https://www.eurekalert.org/pub_releases/2021-01/ez-sar011921.php

Mystery of Martian glaciers revealed

https://www.eurekalert.org/pub_releases/2021-01/cu-mom011921.php
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/20/2021 09:40 am
The future large obliquity of Jupiter

Aims: We aim to determine whether Jupiter's obliquity is bound to remain exceptionally small in the Solar System, or if it could grow in the future and reach values comparable to those of the other giant planets.
Methods: The spin axis of Jupiter is subject to the gravitational torques from its regular satellites and from the Sun. These torques evolve over time due to the long-term variations of its orbit and to the migration of its satellites. With numerical simulations, we explore the future evolution of Jupiter's spin axis for different values of its moment of inertia and for different migration rates of its satellites. Analytical formulas show the location and properties of all relevant resonances.
Results: Because of the migration of the Galilean satellites, Jupiter's obliquity is currently increasing, as it adiabatically follows the drift of a secular spin-orbit resonance with the nodal precession mode of Uranus. Using the current estimates of the migration rate of the satellites, the obliquity of Jupiter can reach values ranging from 6° to 37° after 5 Gyrs from now, according to the precise value of its polar moment of inertia. A faster migration for the satellites would produce a larger increase in obliquity, as long as the drift remains adiabatic.
Conclusions: Despite its peculiarly small current value, the obliquity of Jupiter is no different from other obliquities in the Solar System: It is equally sensitive to secular spin-orbit resonances and it will probably reach comparable values in the future.

https://arxiv.org/abs/2101.06997
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/20/2021 09:49 am
WASP-107b's Density Is Even Lower: A Case Study for the Physics of Planetary Gas Envelope Accretion and Orbital Migration

Abstract
With a mass in the Neptune regime and a radius of Jupiter, WASP-107b presents a challenge to planet formation theories. Meanwhile, the planet's low surface gravity and the star's brightness also make it one of the most favorable targets for atmospheric characterization. Here, we present the results of an extensive 4 yr Keck/HIRES radial-velocity (RV) follow-up program of the WASP-107 system and provide a detailed study of the physics governing the accretion of the gas envelope of WASP-107b. We reveal that WASP-107b's mass is only 1.8 Neptune masses (M b  = 30.5 ± 1.7 M ⊕). The resulting extraordinarily low density suggests that WASP-107b has a H/He envelope mass fraction of &gt;85% unless it is substantially inflated. The corresponding core mass of  &lt;4.6 M ⊕ at 3σ is significantly lower than what is traditionally assumed to be necessary to trigger massive gas envelope accretion. We demonstrate that this large gas-to-core mass ratio most plausibly results from the onset of accretion at gsim1 au onto a low-opacity, dust-free atmosphere and subsequent migration to the present-day a b  = 0.0566 ± 0.0017 au. Beyond WASP-107b, we also detect a second, more massive planet (${M}_{c}\sin i=0.36\pm 0.04{M}_{J}$) on a wide eccentric orbit (e c  = 0.28 ± 0.07) that may have influenced the orbital migration and spin–orbit misalignment of WASP-107b. Overall, our new RV observations and envelope accretion modeling provide crucial insights into the intriguing nature of WASP-107b and the system's formation history. Looking ahead, WASP-107b will be a keystone planet to understand the physics of gas envelope accretion.

https://iopscience.iop.org/article/10.3847/1538-3881/abcd3c
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2021 02:45 pm
Astronomers estimate Titan’s largest sea is 1,000 feet deep

https://news.cornell.edu/stories/2021/01/astronomers-estimate-titans-largest-sea-1000-feet-deep
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2021 02:50 pm
ESOCast 233 Light: Six-Exoplanet System w. Rhythmic Movement Challenges Theories of How Planets Form


https://youtu.be/jXOlaP6tqKQ
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2021 05:24 pm
The 7 Rocky TRAPPIST-1 Planets May Be Made of Similar Stuff

https://www.jpl.nasa.gov/news/the-7-rocky-trappist-1-planets-may-be-made-of-similar-stuff/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/26/2021 06:29 pm
Six Stars, Six Eclipses: ‘The Fact That It Exists Blows My Mind’

https://www.nytimes.com/2021/01/23/science/six-stars-eclipses.html
Title: Astronomy & Planetary Science Thread
Post by: Star One on 01/28/2021 02:29 pm
Quote
Scientists have calculated the mass range for Dark Matter – and it’s tighter than the science world thought.   

Their findings – due to be published in Physical Letters B in March - radically narrow the range of potential masses for Dark Matter particles, and help to focus the search for future Dark Matter-hunters.  The University of Sussex researchers used the established fact that gravity acts on Dark Matter just as it acts on the visible universe to work out the lower and upper limits of Dark Matter’s mass.

https://www.sussex.ac.uk/news/all?id=54482

Quote
A combination of observational data and sophisticated computer simulations have yielded advances in a field of astrophysics that has languished for half a century. The Dark Energy Survey, which is hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, has published a burst of new results on what’s called intracluster light, or ICL, a faint type of light found inside galaxy clusters.

https://news.fnal.gov/2021/01/precision-measurements-of-intracluster-light-suggest-possible-link-to-dark-matter/
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 01/29/2021 07:41 am
Quote
Scientists have calculated the mass range for Dark Matter – and it’s tighter than the science world thought.   

Their findings – due to be published in Physical Letters B in March - radically narrow the range of potential masses for Dark Matter particles, and help to focus the search for future Dark Matter-hunters.  The University of Sussex researchers used the established fact that gravity acts on Dark Matter just as it acts on the visible universe to work out the lower and upper limits of Dark Matter’s mass.

https://www.sussex.ac.uk/news/all?id=54482

Quote
A combination of observational data and sophisticated computer simulations have yielded advances in a field of astrophysics that has languished for half a century. The Dark Energy Survey, which is hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, has published a burst of new results on what’s called intracluster light, or ICL, a faint type of light found inside galaxy clusters.

https://news.fnal.gov/2021/01/precision-measurements-of-intracluster-light-suggest-possible-link-to-dark-matter/

Apparently this was a "rediscovery" (with far more PR) from a 2018 (!) result:

https://twitter.com/mireiamontesq/status/1354912850289041413
Title: Astronomy & Planetary Science Thread
Post by: Star One on 02/01/2021 02:17 pm
School-Going Teenagers Discover Four Planets—One Super-Earth and Three Sub-Neptunes—Orbiting a Nearby Star

https://weather.com/en-IN/india/space/news/2021-01-29-school-going-teenagers-discover-four-planets-orbiting-a-nearby-star

Related paper:

https://iopscience.iop.org/article/10.3847/1538-3881/abd73e
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/01/2021 08:27 pm
Discovery of stars sheds new light on dark matter and galactic cannibalism

https://www.google.co.uk/amp/s/amp.theguardian.com/science/2021/feb/01/discovery-of-outer-stars-of-dwarf-galaxy-sheds-new-light-on-dark-matter
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/06/2021 08:42 pm
Cool Worlds - Discovery of a Strange New World

https://youtu.be/RuyLMDaodlo
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 02/08/2021 09:38 pm
That’s not my reading, as from the articles I’ve read it’s being seriously investigated by other teams including at PADME in Frascati, Italy with the experiment being run again next year with improved performance, with the results expected in 2021.

People are looking, since it's not a terribly expensive experiment to do (by high-energy physics standards) and it would definitely be extremely interesting if true. However, until some other group confirms the existence of the purported X17 particle, people are going to be sceptical. The group that claims detection has had a bit of a habit of finding stuff the others have never confirmed.

Yet I’ve seen their work described as high quality. The first paper was successfully peer reviewed, and the expectation from what I could see wasn’t expected to be any different for this one.

Seems like the hypothetical X17 can be explained via the standard model.
https://arxiv.org/abs/2102.01127

Quote
A Standard Model Explanation for the "ATOMKI Anomaly"

A. Aleksejevs, S. Barkanova, Yu.G. Kolomensky, B. Sheff

Using the e+e− pair spectrometer at the 5 MV Van de Graaff accelerator at the Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Krasznahorkay et al. have claimed a 6.8σ excess at high e+e− opening angles in the internal pair creation isoscalar transition 8Be(18.15)→8Bee+e−. A hypothetical gauge boson with the mass circa 17 MeV, "X17", has been proposed as an explanation for the excess. We show that the observed experimental structure can be reproduced within the Standard Model by adding the full set of second-order corrections and the interference terms to the Born-level decay amplitudes considered by Krasznahorkay et al. We implement a detailed model of the ATOMKI detector, and also show how experimental selection and acceptance bias exacerbate the apparent difference between the experimental data and the Born-level prediction.

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2021 09:18 am
Evidence for chromium hydride in the atmosphere of hot Jupiter WASP-31b

Context. The characterisation of exoplanet atmospheres has shown a wide diversity of compositions. Hot Jupiters have the appropriate temperatures to host metallic compounds, which should be detectable through transmission spectroscopy.
Aims. We aim to detect exotic species in the transmission spectra of hot Jupiters, specifically WASP-31b, by testing a variety of chemical species to explain the spectrum.
Methods. We conduct a re-analysis of publicly available transmission data of WASP-31b using the Bayesian retrieval framework TAUREX II. We retrieve various combinations of the opacities of 25 atomic and molecular species to determine the minimum set that is needed to fit the observed spectrum.
Results. We report evidence for the spectroscopic signatures of chromium hydride (CrH), H2O, and K in WASP-31b. Compared to a flat model without any signatures, a CrH-only model is preferred with a statistical significance of ~3.9σ. A model consisting of both CrH and H2O is found with ~2.6 and ~3σ confidence over a CrH-only model and an H2O-only model, respectively. Furthermore, weak evidence for the addition of K is found at ~2.2σ over the H2O+CrH model, although the fidelity of the data point associated with this signature was questioned in earlier studies. Finally, the inclusion of collision-induced absorption and a Rayleigh scattering slope (indicating the presence of aerosols) is found with ~3.5σ confidence over the flat model. This analysis presents the first evidence for signatures of CrH in a hot Jupiter atmosphere. At a retrieved temperature of 1481−355+264 K, the atmosphere of WASP-31b is hot enough to host gaseous Cr-bearing species, and the retrieved abundances agree well with predictions from thermal equilibrium chemistry. Furthermore, the retrieved abundance of CrH agrees with the abundance in an L-type brown dwarf atmosphere. However, additional retrievals using VLT FORS2 data lead to a non-detection of CrH. Future observations with James Webb Space Telescope have the potential to confirm the detection and/or discover other CrH features.

https://www.aanda.org/articles/aa/full_html/2021/02/aa39509-20/aa39509-20.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2021 09:32 am
Size and structures of disks around very low mass stars in the Taurus star-forming region★

Context. The discovery of giant planets orbiting very low mass stars (VLMS) and the recent observed substructures in disks around VLMS is challenging planet formation models. Specifically, radial drift of dust particles is a catastrophic barrier in these disks, which prevents the formation of planetesimals and therefore planets.
Aims. We aim to estimate if structures, such as cavities, rings, and gaps, are common in disks around VLMS and to test models of structure formation in these disks. We also aim to compare the radial extent of the gas and dust emission in disks around VLMS, which can give us insight about radial drift.
Methods. We studied six disks around VLMS in the Taurus star-forming region using ALMA Band 7 (~340 GHz) at a resolution of ~0.1″. The targets were selected because of their high disk dust content in their stellar mass regime.
Results. Our observations resolve the disk dust continuum in all disks. In addition, we detect the 12CO (J = 3−2) emission line in all targets and 13CO (J = 3−2) in five of the six sources. The angular resolution allows the detection of dust substructures in three out of the six disks, which we studied by using UV-modeling. Central cavities are observed in the disks around stars MHO 6 (M 5.0) and CIDA 1 (M 4.5), while we have a tentative detection of a multi-ringed disk around J0433. We estimate that a planet mass of ~0.1 MJup or ~0.4 MSaturn is required for a single planet to create the first gap in J0433. For the cavities of MHO 6 and CIDA 1, a Saturn-mass planet (~0.3 MJup) is required. The other three disks with no observed structures are the most compact and faintest in our sample, with the radius enclosing 90% of the continuum emission varying between ~13 and 21 au. The emission of 12CO and 13CO is more extended than the dust continuum emission in all disks of our sample. When using the 12CO emission to determine the gas disk extension Rgas, the ratio of Rgas∕Rdust in our sample varies from 2.3 to 6.0. One of the disks in our sample, CIDA 7, has the largest Rgas∕Rdust ratio observed so far, which is consistent with models of radial drift being very efficient around VLMS in the absence of substructures.
Conclusions. Given our limited angular resolution, substructures were only directly detected in the most extended disks, which represent 50% of our sample, and there are hints of unresolved structured emission in one of the bright smooth sources. Our observations do not exclude giant planet formation on the substructures observed. A comparison of the size and luminosity of VLMS disks with their counterparts around higher mass stars shows that they follow a similar relation.

https://www.aanda.org/articles/aa/full_html/2021/01/aa38983-20/aa38983-20.html
Title: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2021 09:39 am
Six transiting planets and a chain of Laplace resonances in TOI-178

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at a 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152(-0.070/+0.073) to 2.87(-0.13/+0.14) Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02(+0.28/-0.23) to 0.177(+0.055/-0.061) times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

https://arxiv.org/abs/2101.09260

Artist animation of the system:

https://youtu.be/-WevvRG9ysY

https://www.eso.org/public/archives/releases/sciencepapers/eso2102/eso2102a.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2021 09:50 am
Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides

Abstract
We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N-body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host star and the planet densities. We find that all seven planets' densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements, such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses to a precision of 3%–5%, equivalent to a radial-velocity (RV) precision of 2.5 cm s−1, or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet; we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities for the formation, migration, and evolution of the planet system.

https://iopscience.iop.org/article/10.3847/PSJ/abd022

https://www.unibe.ch/news/media_news/media_relations_e/media_releases/2021/media_releases_2021/trappist_1_s_7_rocky_planets_may_be_made_of_similar_stuff/index_eng.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2021 02:34 pm
Standing on the Shoulders of Giants: New Mass and Distance Estimates for Betelgeuse through Combined Evolutionary, Asteroseismic, and Hydrodynamic Simulations with MESA

Abstract
We conduct a rigorous examination of the nearby red supergiant Betelgeuse by drawing on the synthesis of new observational data and three different modeling techniques. Our observational results include the release of new, processed photometric measurements collected with the space-based Solar Mass Ejection Imager instrument prior to Betelgeuse's recent, unprecedented dimming event. We detect the first radial overtone in the photometric data and report a period of 185 ± 13.5 days. Our theoretical predictions include self-consistent results from multi-timescale evolutionary, oscillatory, and hydrodynamic simulations conducted with the Modules for Experiments in Stellar Astrophysics software suite. Significant outcomes of our modeling efforts include a precise prediction for the star's radius: ${764}_{-62}^{+116}\,{R}_{\odot }$. In concert with additional constraints, this allows us to derive a new, independent distance estimate of ${168}_{-15}^{+27}$ pc and a parallax of $\pi ={5.95}_{-0.85}^{+0.58}$ mas, in good agreement with Hipparcos but less so with recent radio measurements. Seismic results from both perturbed hydrostatic and evolving hydrodynamic simulations constrain the period and driving mechanisms of Betelgeuse's dominant periodicities in new ways. Our analyses converge to the conclusion that Betelgeuse's ≈400 day period is the result of pulsation in the fundamental mode, driven by the κ-mechanism. Grid-based hydrodynamic modeling reveals that the behavior of the oscillating envelope is mass-dependent, and likewise suggests that the nonlinear pulsation excitation time could serve as a mass constraint. Our results place α Orionis definitively in the early core helium-burning phase of the red supergiant branch. We report a present-day mass of 16.5–19 M —slightly lower than typical literature values.

https://iopscience.iop.org/article/10.3847/1538-4357/abb8db
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/10/2021 03:30 pm
Now it’s the turn of Alpha Centauri A to host a possible exoplanet following in the footsteps of Proxima Centauri, in this case it’s a warm Neptune in its habitable zone. As ever more data is needed as instrumental artefact cannot be ruled at this time.

Imaging low-mass planets within the habitable zone of α Centauri

Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged. Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, α Centauri. Based on 75–80% of the best quality images from 100 h of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of α Centauri A. This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around α Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes.

https://www.nature.com/articles/s41467-021-21176-6

https://www.scientificamerican.com/article/is-it-a-planet-astronomers-spy-promising-potential-world-around-alpha-centauri/
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 02/10/2021 10:16 pm
Now it’s the turn of Alpha Centauri A to host a possible exoplanet following in the footsteps of Proxima Centauri, in this case it’s a warm Neptune in its habitable zone. As ever more data is needed as instrumental artefact cannot be ruled at this time.

Much as the Pale Red Dot campaign studied Proxima, a study group called the Near Earths in the Alpha Cen Region (NEAR) did a similar effort for the larger members of Alpha Centauri.  The infrared capabilities of the Very Large Telescope were key to the tentative planet's discovery.

A PDF with additional details:

http://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf (http://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/11/2021 10:33 am
Now it’s the turn of Alpha Centauri A to host a possible exoplanet following in the footsteps of Proxima Centauri, in this case it’s a warm Neptune in its habitable zone. As ever more data is needed as instrumental artefact cannot be ruled at this time.

Much as the Pale Red Dot campaign studied Proxima, a study group called the Near Earths in the Alpha Cen Region (NEAR) did a similar effort for the larger members of Alpha Centauri.  The infrared capabilities of the Very Large Telescope were key to the tentative planet's discovery.

A PDF with additional details:

http://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf (http://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf)
I am guessing that a warm Neptune confirmed in that orbit would have ramifications for the whole system as it possible means that more rocky terrestrial planets suitable for life would have been scattered out of the system if it likely formed further out and then moved inwards towards the star.   
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 02/11/2021 07:50 pm
Now it’s the turn of Alpha Centauri A ...

Named Rigil Kentaurus. (B is named Toliman and C is named Proxima Centauri.) Just for interest. :)
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/12/2021 06:31 am
Quote
If you could explore Earth’s surface a billion years ago, the most remarkable sight might be the world’s un-remarkability. There would be no trees or bugs, nor birds overhead. The only life is simple and small, a slimy oceanic soup.
And a new study published in Science points to yet another feature that may be missing: towering mountains.

https://www.google.co.uk/amp/s/api.nationalgeographic.com/distribution/public/amp/science/2021/02/earths-mountains-may-have-mysteriously-stopped-growing-for-a-billion-years

Related paper:

https://science.sciencemag.org/content/371/6530/728
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/15/2021 10:47 am
Solar System’s Most Distant Known Member Confirmed

https://carnegiescience.edu/news/solar-systems-most-distant-known-member-confirmed
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/15/2021 07:42 pm
Chronostratigraphy of a 270-ka sediment record from Lake Selina, Tasmania: Combining radiometric, geomagnetic and climatic dating

Abstract
Lake sediment archives covering several glacial cycles are scarce in the Southern Hemisphere and they are challenging to date. Here we present the chronostratigraphy of the oldest continuous lake sediment archive in Tasmania, Australia; a 5.5 m and 270 ka (Marine Isotope Stage 8) sediment core from Lake Selina. We employ radiometric dating (radiocarbon and optically stimulated luminescence) and relative dating (geomagnetic and climate comparisons). Bayesian modeling of the radiometric ages reaches back to 80 ka (1.7 m) and relative dating using a dynamic programing algorithm allows dating of the full sequence. Elemental data, magnetic properties and beryllium isotopes from Lake Selina reveal a close fit to Antarctic ice core climate proxies. Weaker correlation during the Last Glacial Period (MIS 2–4) is attributed to additional local factors impacting Lake Selina proxies at a time of climate changes and human arrival into Tasmania. Over that period, full vector paleomagnetic records and authigenic 10Be/9Be ratios are combined to identify the Laschamp geomagnetic excursion for the first time in Australia and constrain the chronology. The multi-method approach provides two preferred age models, indiscernible within their uncertainties, which allows the use of a geomagnetic dipole-independent (full archive) or a climate-independent (111 ka to present) age model.

https://www.sciencedirect.com/science/article/abs/pii/S1871101421000030
Title: Astronomy & Planetary Science Thread
Post by: Star One on 02/18/2021 08:52 am
Breakup of a long-period comet as the origin of the dinosaur extinction

The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here, we show that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population could increase the impact rate of long-period comets capable of producing Chicxulub impact events by an order of magnitude. This new rate would be consistent with the age of the Chicxulub impact crater, thereby providing a satisfactory explanation for the origin of the impactor. Our hypothesis explains the composition of the largest confirmed impact crater in Earth’s history as well as the largest one within the last million years. It predicts a larger proportion of impactors with carbonaceous chondritic compositions than would be expected from meteorite falls of main-belt asteroids.

https://www.nature.com/articles/s41598-021-82320-2

Quote
Other researchers did not agree with the new study's findings and still say several clues point to an asteroid creating the Chicxulub crater.
For one, Iridium -- along with a handful of other chemical elements -- was found scattered around the globe after the impact, said David Kring, principal scientist at the Lunar and Planetary Institute in Houston, who was not involved with the comet study.
Kring said the proportions of those elements are the same proportions seen in meteorite samples of asteroids.
The comet piece would have also been too small to make a crater of that size, said Natalia Artemieva, senior scientist at the Planetary Science Institute, who also was not involved in the study.
The study estimated the size of the comet piece to be about 4 miles wide, and Artemieva argued the comet would need to be at least 7.5 miles wide to make a crater the size of Chicxulub. With the small comet piece, she said, "it is absolutely impossible," and the crater size from the impact would be at least half the size.

https://edition.cnn.com/2021/02/17/world/dinosaur-extinction-comet-study-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/26/2021 10:12 am
Scientists claim that all high-energy cosmic neutrinos are born by quasars
Quote
Scientists of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS), the Moscow Institute of Physics and Technology (MIPT) and the Institute for Nuclear Research of RAS (INR RAS) studied the arrival directions of astrophysical neutrinos with energies more than a trillion electronvolts (TeV) and came to an unexpected conclusion: all of them are born near black holes in the centers of distant active galaxies powerful radio sources. Previously, only neutrinos with the highest energies were assumed to be obtained in sources of this class.

https://www.eurekalert.org/pub_releases/2021-02/miop-sct022221.php
Title: Astronomy & Planetary Science Thread
Post by: Star One on 02/26/2021 06:50 pm
Astronomers Find an Astonishing 'Super-Earth' That's Nearly as Old as The Universe

Quote
But the TOI-561 system, planets and all, is one of the oldest ever seen, at an estimated age of around 10 billion years.

That's more than twice as old as the Solar System, nearly as old as the Universe itself, and evidence that rocky exoplanets can remain stable for a very long time.

"TOI-561 b is one of the oldest rocky planets yet discovered," said astronomer Lauren Weiss of the University of Hawai'i.

"Its existence shows that the universe has been forming rocky planets almost since its inception 14 billion years ago."

The three planets, named TOI-561 b, TOI-561 c and TOI-561 d, were identified by NASA's planet-hunting space telescope, TESS. TESS stares at sections of the sky, looking for periodic, faint dips in the light of distant stars. These are transits, when a planet passes between us and its star.

https://www.sciencealert.com/an-astonishing-super-earth-exoplanet-is-nearly-as-old-as-the-universe

https://youtu.be/SNjn9bzbN_Y
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/03/2021 07:26 pm
Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm

The model of cylindrical anisotropy in the inner core (IC) states that seismic rays traveling parallel to the Earth's rotational axis travel faster than those parallel to the equator. There have been continuing discrepancies in estimates of the strength and orientation of anisotropy, with some evidence suggesting that such a model may not be supported by available data. Here, we scrutinize the radial dependence of anisotropy within the IC, where the nature of anisotropy has been shown to change anywhere between a 300 and 800 km radius. We use recent travel time data from the International Seismological Centre in conjunction with the neighborhood algorithm to provide a robust means of testing this idea, through examination of an ensemble of models that satisfactorily fit the data. This can be done with no explicit regularization and without the need for subjective choices associated with binning of phase data. In addition, uncertainty bounds are calculated for anisotropic parameters using a likelihood ratio approach. We find evidence to suggest that commonly employed spatial averaging (binning) methods may be detrimental to obtaining reliable results. We conclude that there is no significant change in the strength of anisotropy with depth in the IC. Instead, we find a change in the slow direction of anisotropy to 54° within the innermost IC at an ∼650 km radius with fast direction parallel to the Earth's rotational axis.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JB020545?fbclid=IwAR2NX7XBgAOpdnsMEpExxpb4GCHGB8RT6xyoGRKX7OxYsxH-RxfZB2p4Qtk
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/06/2021 06:30 pm
Hemispheric Tectonics on LHS 3844b

Abstract
The tectonic regime of rocky planets fundamentally influences their long-term evolution and cycling of volatiles between interior and atmosphere. Earth is the only known planet with active plate tectonics, but observations of exoplanets may deliver insights into the diversity of tectonic regimes beyond the solar system. Observations of the thermal phase curve of super-Earth LHS 3844b reveal a solid surface and lack of a substantial atmosphere, with a temperature contrast between the substellar and antistellar point of around 1000 K. Here, we use these constraints on the planet's surface to constrain the interior dynamics and tectonic regimes of LHS 3844b using numerical models of interior flow. We investigate the style of interior convection by assessing how upwellings and downwellings are organized and how tectonic regimes manifest. We discover three viable convective regimes with a mobile surface: (1) spatially uniform distribution of upwellings and downwellings, (2) prominent downwelling on the dayside and upwellings on the nightside, and (3) prominent downwelling on the nightside and upwellings on the dayside. Hemispheric tectonics is observed for regimes (2) and (3) as a direct consequence of the day-to-night temperature contrast. Such a tectonic mode is absent in the present-day solar system and has never been inferred from astrophysical observations of exoplanets. Our models offer distinct predictions for volcanism and outgassing linked to the tectonic regime, which may explain secondary features in phase curves and allow future observations to constrain the diversity of super-Earth interiors.

https://iopscience.iop.org/article/10.3847/2041-8213/abe400
Title: Re: Astronomy & Planetary Science Thread
Post by: jbenton on 03/09/2021 05:58 am
https://www.space.com/black-holes-not-black-planck-heart

Quote
One theory of black hole singularities replaces those infinitely tiny points of infinitely compressed matter with something much more palatable: an incredibly tiny point of incredibly compressed matter. This is called a Planck core, because the idea theorizes that the matter inside a black hole is compressed all the way down to the smallest possible scale, the Planck length, which is 1.6 * 10^ minus 35 meters.

That's … small.

With a Planck core, which wouldn’t be a singularity, a black hole would no longer host an event horizon — there would be no place where the gravitational pull exceeds the speed of light. But to outside observers, the gravitational pull would be so strong that it would look and act like an event horizon. Only extremely sensitive observations, which we do not yet have the technology for, would be able to tell the difference
Title: Astronomy & Planetary Science Thread
Post by: Star One on 03/09/2021 07:18 am
Unprecedented find for the U.K. especially as the object was seen to come down and it’s orbit already worked out so it’s known where it came from, and it was collected so quickly it is almost as good as material brought back by probes to meteorites. Most of the material so far recovered has been lodged at the Natural History Museum.

Winchcombe meteorite is first UK find in 30 years:

https://www.bbc.co.uk/news/science-environment-56326246
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/09/2021 09:35 am
https://www.space.com/black-holes-not-black-planck-heart

Quote
One theory of black hole singularities replaces those infinitely tiny points of infinitely compressed matter with something much more palatable: an incredibly tiny point of incredibly compressed matter. This is called a Planck core, because the idea theorizes that the matter inside a black hole is compressed all the way down to the smallest possible scale, the Planck length, which is 1.6 * 10^ minus 35 meters.

That's … small.

With a Planck core, which wouldn’t be a singularity, a black hole would no longer host an event horizon — there would be no place where the gravitational pull exceeds the speed of light. But to outside observers, the gravitational pull would be so strong that it would look and act like an event horizon. Only extremely sensitive observations, which we do not yet have the technology for, would be able to tell the difference
That link doesn’t work so I am guessing they moved the webpage. It is now as follows:

https://www.space.com/black-holes-not-black-planck-hearts
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/10/2021 07:22 am
Quote
A chunk of meteorite found in the desert sands of Algeria could be a piece of a baby planet that never made it.

According to an in-depth analysis of the rock's composition and age, not only is the meteorite known as Erg Chech 002 older than Earth, it formed volcanically - suggesting that it could have once been part of the crust of an object known as a protoplanet.

https://www.sciencealert.com/earth-s-oldest-known-volcanic-rock-could-be-a-piece-of-lost-protoplanet

A 4,565-My-old andesite from an extinct chondritic protoplanet

Abstract

The age of iron meteorites implies that accretion of protoplanets began during the first millions of years of the solar system. Due to the heat generated by 26Al decay, many early protoplanets were fully differentiated with an igneous crust produced during the cooling of a magma ocean and the segregation at depth of a metallic core. The formation and nature of the primordial crust generated during the early stages of melting is poorly understood, due in part to the scarcity of available samples. The newly discovered meteorite Erg Chech 002 (EC 002) originates from one such primitive igneous crust and has an andesite bulk composition. It derives from the partial melting of a noncarbonaceous chondritic reservoir, with no depletion in alkalis relative to the Sun’s photosphere and at a high degree of melting of around 25%. Moreover, EC 002 is, to date, the oldest known piece of an igneous crust with a 26Al-26Mg crystallization age of 4,565.0 million years (My). Partial melting took place at 1,220 °C up to several hundred kyr before, implying an accretion of the EC 002 parent body ca. 4,566 My ago. Protoplanets covered by andesitic crusts were probably frequent. However, no asteroid shares the spectral features of EC 002, indicating that almost all of these bodies have disappeared, either because they went on to form the building blocks of larger bodies or planets or were simply destroyed.

https://www.pnas.org/content/118/11/e2026129118
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/11/2021 10:38 am
Quote
Evidence of a rare neutrino-interaction process called the Glashow resonance has been observed by a detector buried deep in the Antarctic ice — opening up a way to probe neutrino formation in astrophysical sources.

https://www.nature.com/articles/d41586-021-00486-1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/11/2021 07:01 pm
Detailed article on the Winchcombe meteorite and its significance.

https://www.nationalgeographic.com/science/article/newfound-meteorite-could-help-unlock-secrets-of-the-solar-system
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/16/2021 08:51 am
The discovery of a highly accreting, radio-loud quasar at z=6.82

Radio sources at the highest redshifts can provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. The number of astronomical objects identified at z&gt;6 has increased dramatically over the last few years, but previously only three radio-loud (R2500&gt;10) sources had been reported at z&gt;6, with the most distant being a quasar at z=6.18. Here we present the discovery and characterization of P172+18, a radio-loud quasar at z=6.823. This source has an MgII-based black hole mass of ~3x10^8 Msun and is one of the fastest accreting quasars, consistent with super-Eddington accretion. The ionized region around the quasar is among the largest measured at these redshifts, implying an active phase longer than the average lifetime of the z&gt;6 quasar population. From archival data, there is evidence that its 1.4 GHz emission has decreased by a factor of two over the last two decades. The quasar's radio spectrum between 1.4 and 3.0 GHz is steep (alpha=-1.31) and has a radio-loudness parameter R2500~90. A second steep radio source (alpha=-0.83) of comparable brightness to the quasar is only 23.1" away (~120 kpc at z=6.82; projection probability &lt;2%), but shows no optical or near-infrared counterpart. Further follow-up is required to establish whether these two sources are physically associated.

https://arxiv.org/abs/2103.03295

https://phys.org/news/2021-03-distant-radio-loud-quasar.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/17/2021 09:56 pm
1I/‘Oumuamua as an N2 ice fragment of an exoPluto surface: I. Size and Compositional Constraints

1I/‘Oumuamua is very strange and it is hard to explain where it came from. We looked at several different ices and the push they would give ‘Oumuamua as they evaporated. We found that the best ice is nitrogen (N2), which would explain many of the things we know about it. ‘Oumuamua was small, about half as long as a city block and only as thick as a three story building, but it was very shiny. The shininess is about the same as the surfaces of Pluto and Triton, which are also covered in nitrogen ice. We suggest ‘Oumuamua was probably thrown out of a young star system about half a billion years ago. Bodies like ‘Oumuamua may allow us to see what the surfaces of a so far unknown type of exoplanet, “exoPlutos”, are made of. In a following paper (Desch &amp; Jackson, 2021) we show that orbital instabilities in which giant planets move around, as happened in our own outer solar system 4 billion years ago, could make and throw out large numbers of small pieces of nitrogen ice like ‘Oumuamua. ‘Oumuamua may be the first piece of an exoplanet brought to us.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JE006706

1I/‘Oumuamua as an N2 ice fragment of an exopluto surface II: Generation of N2 ice fragments and the origin of ‘Oumuamua

Our Kuiper belt originally had much more mass than today, but an instability caused by Neptune’s migration disrupted their orbits, ejecting most of this material from the Solar System, and simultaneously causing numerous collisions among these bodies. There were thousands of bodies like Pluto, with N2 ice (like the gas in Earth’s atmosphere, but frozen) on their surfaces, and this instability would have generated trillions of N2 ice fragments. A similar fragment, generated in another solar system, after travelling for about a half billion years through interstellar space, would match the size, shape, brightness, and dynamics of the interstellar object 1I/‘Oumuamua. The odds of detecting such an object, as well as more cometlike objects like the interstellar object 2I/Borisov, are consistent with the numbers of such objects we expect in interstellar space if most stellar systems ejected comets and N2 ice fragments with the same efficiency our solar system did. This implies other stellar systems also had Kuiper belts and similar instabilities. There are hints that some N2 ice fragments may have survived in the Oort cloud of comets in our Solar System. ‘Oumuamua may be the first sample of an exoplanet born around another star, brought to Earth.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JE006807
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/18/2021 02:43 pm
Summary
Over time, sea levels have risen and fallen with temperatures—but Earth's total surface water was always assumed to be constant. Now, evidence is mounting that some 3 billion to 4 billion years ago, the planet's oceans held nearly twice as much water—enough to submerge today's continents. Rocks in today's mantle, the thick layer beneath the crust, are thought to sequester an ocean's worth of water or more in their mineral structures. But early in Earth's history, the mantle, warmed by radioactivity, was four times hotter. Work using hydraulic presses has shown that many minerals would be unable to hold as much hydrogen and oxygen at mantle temperatures and pressures. A new model of the mantle's evolution through time, based on these results, suggests the mantle could have held far less water in the past. And the most likely home for that water was the surface. This flood could have primed the engine of plate tectonics and made it more difficult for life to start on land.

https://science.sciencemag.org/content/371/6534/1088
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/20/2021 04:03 pm
New nova in Cassiopeia brightens rapidly

Quote
There’s a ‘new star’ – a classical nova – on show among the stars of the far-northern constellation of Cassiopeia. Nova Cas 2021 was discovered on 18 March shining at around magnitude +9.6, but it appears to have brightened rapidly to around magnitude +7.5 on 19 March.

Quote
Nova Cas 2021 was discovered by Yuji Nakamura of Japan on 18 March at about 10h UT, when it shone at around magnitude +9.6. He shot four 15-second frames with a 135mm, f/4 lens coupled to a CCD camera (a set-up which provided a limiting magnitude of +12) and further reported that no object was seen at the transient object’s position on frames shot with the same equipment on 14 March.

Just hours later, professional astronomers from the National Astronomical Observatory of Japan swung into action, obtaining a spectrum of the object with the 3.8-m Seimei Telescope at Okayama Observatory and photometry through a 0.4-m telescope at Kyoto University. The spectrum revealed the tell tale features of a classical nova, with emission lines of the Balmer series, N-III 4640 and He-II 4686, and He-I emission lines with P-Cyg profiles. They further found and identified lines N-II 5679, C-III 5695 and Paschen emission lines. The position of Nova Cas 2021 precisely coincides with that of the W UMa-type eclipsing variable star CzeV3217, which lies at a distance of about 5,500 light years.

https://astronomynow.com/2021/03/19/new-nova-in-cassiopeia-brightens-rapidly/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/22/2021 03:47 pm
A Restless Supermassive Black Hole in the Galaxy J0437+2456

Abstract
We present the results from an observing campaign to confirm the peculiar motion of the supermassive black hole (SMBH) in J0437+2456 first reported in Pesce et al. Deep observations with the Arecibo Observatory have yielded a detection of neutral hydrogen (H i) emission, from which we measure a recession velocity of 4910 km s−1 for the galaxy as a whole. We have also obtained near-infrared integral field spectroscopic observations of the galactic nucleus with the Gemini North telescope, yielding spatially resolved stellar and gas kinematics with a central velocity at the innermost radii (0farcs1 ≈ 34 pc) of 4860 km s−1. Both measurements differ significantly from the ~4810 km s−1 H2O megamaser velocity of the SMBH, supporting the prior indications of a velocity offset between the SMBH and its host galaxy. However, the two measurements also differ significantly from one another, and the galaxy as a whole exhibits a complex velocity structure that implies that the system has recently been dynamically disturbed. These results make it clear that the SMBH is not at rest with respect to the systemic velocity of the galaxy, though the specific nature of the mobile SMBH—i.e., whether it traces an ongoing galaxy merger, a binary black hole system, or a gravitational-wave recoil event—remains unclear.

https://iopscience.iop.org/article/10.3847/1538-4357/abde3d

https://www.independent.co.uk/life-style/gadgets-and-tech/black-hole-space-racing-b1820534.html
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/22/2021 03:59 pm
Long form documentary - Inside The Controversy Over Building One Of The World’s Largest Telescopes - Beyond The Mauna:

https://youtu.be/poRZ5lwCML0

I wonder if the TMT is now dead or not?
Title: Re: Astronomy &amp; Planetary Science Thread
Post by: jbenton on 03/23/2021 04:50 am
I wonder if the TMT is now dead or not?

I remember reading a couple of years ago that they had an alternate location in mind in the Canary Islands. Not ideal, but workable.
Title: Re: Astronomy &amp; Planetary Science Thread
Post by: tpw2 on 03/23/2021 06:38 am
I wonder if the TMT is now dead or not?

I remember reading a couple of years ago that they had an alternate location in mind in the Canary Islands. Not ideal, but workable.

Yes, there's a planned backup site at the Roque de los Muchachos Observatory on La Palma, in case Mauna Kea is not feasible. But I believe there are still hurdles to clear also with that one and funders will start running out of patience at some point. I wouldn't be surprised if the whole project collapsed.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 03/23/2021 07:11 am
I wonder if the TMT is now dead or not?

I remember reading a couple of years ago that they had an alternate location in mind in the Canary Islands. Not ideal, but workable.

Yes, there's a planned backup site at the Roque de los Muchachos Observatory on La Palma, in case Mauna Kea is not feasible. But I believe there are still hurdles to clear also with that one and funders will start running out of patience at some point. I wouldn't be surprised if the whole project collapsed.
Who are the organisations funding the TMT? As I wonder especially with the pandemic as well possibly hitting them hard economically, depending who they are, they may decide to cut their losses on the project.
Title: Re: Astronomy & Planetary Science Thread
Post by: tpw2 on 03/23/2021 07:20 am
I wonder if the TMT is now dead or not?

I remember reading a couple of years ago that they had an alternate location in mind in the Canary Islands. Not ideal, but workable.

Yes, there's a planned backup site at the Roque de los Muchachos Observatory on La Palma, in case Mauna Kea is not feasible. But I believe there are still hurdles to clear also with that one and funders will start running out of patience at some point. I wouldn't be surprised if the whole project collapsed.
Who are the organisations funding the TMT? As I wonder especially with the pandemic as well they may decide to cut their losses on the project.

The (biggest, at least) funders are the University of California, Caltech, Gordon Moore's (Intel's founder) foundation, and government funding from Canada, China, Japan and India. I'm not sure how much each is contributing, but I think the main sources are the governments of Canada (about $250 million), Japan and China.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/23/2021 09:18 am
I wonder if the TMT is now dead or not?

I remember reading a couple of years ago that they had an alternate location in mind in the Canary Islands. Not ideal, but workable.

Yes, there's a planned backup site at the Roque de los Muchachos Observatory on La Palma, in case Mauna Kea is not feasible. But I believe there are still hurdles to clear also with that one and funders will start running out of patience at some point. I wouldn't be surprised if the whole project collapsed.
Who are the organisations funding the TMT? As I wonder especially with the pandemic as well they may decide to cut their losses on the project.

The (biggest, at least) funders are the University of California, Caltech, Gordon Moore's (Intel's founder) foundation, and government funding from Canada, China, Japan and India. I'm not sure how much each is contributing, but I think the main sources are the governments of Canada (about $250 million), Japan and China.
Are the governments involved going to be so inclined to spend that kind of money on a troubled project with them no doubt looking to cut spending wherever they can at the moment.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/23/2021 08:46 pm
LHC finds tantalising hints of new physics https://www.bbc.co.uk/news/science-environment-56491033

Edited to add the related preprint:

Test of lepton universality in beauty-quark decays

The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton-proton collision data collected with the LHCb detector at CERN's Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the Standard Model, such as a new fundamental interaction between quarks and leptons.

https://arxiv.org/abs/2103.11769
Title: Astronomy & Planetary Science Thread
Post by: Star One on 03/24/2021 02:17 pm
First black hole photo gets an upgrade, revealing extreme magnetic fields

https://www.cnet.com/news/first-black-hole-photo-gets-an-upgrade-revealing-extreme-magnetic-fields/#ftag=CAD-09-10aai5b

Related video:

https://youtu.be/DzZ5mb0SD2E

eso2105 — Science Release

Astronomers image magnetic fields at the edge of M87’s black hole

The Event Horizon Telescope (EHT) collaboration, who produced the first ever image of a black hole, has today revealed a new view of the massive object at the centre of the Messier 87 (M87) galaxy: how it looks in polarised light. This is the first time astronomers have been able to measure polarisation, a signature of magnetic fields, this close to the edge of a black hole. The observations are key to explaining how the M87 galaxy, located 55 million light-years away, is able to launch energetic jets from its core.

“We are now seeing the next crucial piece of evidence to understand how magnetic fields behave around black holes, and how activity in this very compact region of space can drive powerful jets that extend far beyond the galaxy,” says Monika Mościbrodzka, Coordinator of the EHT Polarimetry Working Group and Assistant Professor at Radboud University in the Netherlands.

On 10 April 2019, scientists released the first ever image of a black hole, revealing a bright ring-like structure with a dark central region — the black hole’s shadow. Since then, the EHT collaboration has delved deeper into the data on the supermassive object at the heart of the M87 galaxy collected in 2017. They have discovered that a significant fraction of the light around the M87 black hole is polarised.

“This work is a major milestone: the polarisation of light carries information that allows us to better understand the physics behind the image we saw in April 2019, which was not possible before,” explains Iván Martí-Vidal, also Coordinator of the EHT Polarimetry Working Group and GenT Distinguished Researcher at the University of Valencia, Spain. He adds that “unveiling this new polarised-light image required years of work due to the complex techniques involved in obtaining and analysing the data.”

Light becomes polarised when it goes through certain filters, like the lenses of polarised sunglasses, or when it is emitted in hot regions of space where magnetic fields are present. In the same way that polarised sunglasses help us see better by reducing reflections and glare from bright surfaces, astronomers can sharpen their view of the region around the black hole by looking at how the light originating from it is polarised. Specifically, polarisation allows astronomers to map the magnetic field lines present at the inner edge of the black hole.

“The newly published polarised images are key to understanding how the magnetic field allows the black hole to 'eat' matter and launch powerful jets,” says EHT collaboration member Andrew Chael, a NASA Hubble Fellow at the Princeton Center for Theoretical Science and the Princeton Gravity Initiative in the US.

The bright jets of energy and matter that emerge from M87’s core and extend at least 5000 light-years from its centre are one of the galaxy’s most mysterious and energetic features. Most matter lying close to the edge of a black hole falls in. However, some of the surrounding particles escape moments before capture and are blown far out into space in the form of jets.

Astronomers have relied on different models of how matter behaves near the black hole to better understand this process. But they still don’t know exactly how jets larger than the galaxy are launched from its central region, which is comparable in size to the Solar System, nor how exactly matter falls into the black hole. With the new EHT image of the black hole and its shadow in polarised light, astronomers managed for the first time to look into the region just outside the black hole where this interplay between matter flowing in and being ejected out is happening.

The observations provide new information about the structure of the magnetic fields just outside the black hole. The team found that only theoretical models featuring strongly magnetised gas can explain what they are seeing at the event horizon.

“The observations suggest that the magnetic fields at the black hole’s edge are strong enough to push back on the hot gas and help it resist gravity’s pull. Only the gas that slips through the field can spiral inwards to the event horizon,” explains Jason Dexter, Assistant Professor at the University of Colorado Boulder, US, and Coordinator of the EHT Theory Working Group.

To observe the heart of the M87 galaxy, the collaboration linked eight telescopes around the world — including the northern Chile-based Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX), in which the European Southern Observatory (ESO) is a partner — to create a virtual Earth-sized telescope, the EHT. The impressive resolution obtained with the EHT is equivalent to that needed to measure the length of a credit card on the surface of the Moon.

“With ALMA and APEX, which through their southern location enhance the image quality by adding geographical spread to the EHT network, European scientists were able to play a central role in the research,” says Ciska Kemper, European ALMA Programme Scientist at ESO. “With its 66 antennas, ALMA dominates the overall signal collection in polarised light, while APEX has been essential for the calibration of the image.”

"ALMA data were also crucial to calibrate, image and interpret the EHT observations, providing tight constraints on the theoretical models that explain how matter behaves near the black hole event horizon," adds Ciriaco Goddi, a scientist at Radboud University and Leiden Observatory, the Netherlands, who led an accompanying study that relied only on ALMA observations.

The EHT setup allowed the team to directly observe the black hole shadow and the ring of light around it, with the new polarised-light image clearly showing that the ring is magnetised. The results are published today in two separate papers in The Astrophysical Journal Letters by the EHT collaboration. The research involved over 300 researchers from multiple organisations and universities worldwide.

"The EHT is making rapid advancements, with technological upgrades being done to the network and new observatories being added. We expect future EHT observations to reveal more accurately the magnetic field structure around the black hole and to tell us more about the physics of the hot gas in this region," concludes EHT collaboration member Jongho Park, an East Asian Core Observatories Association Fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taipei.

More information
This research was presented in two papers by the EHT collaboration published today in The Astrophysical Journal Letters: "First M87 Event Horizon Telescope Results VII: Polarization of the Ring" (doi: 10.3847/2041-8213/abe71d) and "First M87 Event Horizon Telescope Results VIII: Magnetic Field Structure Near The Event Horizon" (doi: 10.3847/2041-8213/abe4de). Accompanying research is presented in the paper "Polarimetric properties of Event Horizon Telescope targets from ALMA" (doi: 10.3847/2041-8213/abee6a) by Goddi, Martí-Vidal, Messias, and the EHT collaboration, which has been accepted for publication in The Astrophysical Journal Letters.

The EHT collaboration involves more than 300 researchers from Africa, Asia, Europe, North and South America. The international collaboration is working to capture the most detailed black hole images ever obtained by creating a virtual Earth-sized telescope. Supported by considerable international investment, the EHT links existing telescopes using novel systems — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.

The individual telescopes involved are: ALMA, APEX, the Institut de Radioastronomie Millimetrique (IRAM) 30-meter Telescope, the IRAM NOEMA Observatory, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), the South Pole Telescope (SPT), the Kitt Peak Telescope, and the Greenland Telescope (GLT).

The EHT consortium consists of 13 stakeholder institutes: the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, Radboud University and the Smithsonian Astrophysical Observatory. 

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The BlackHoleCam research group was awarded the European Research Council €14 million Synergy Grant in 2013. The Principal Investigators are Heino Falcke, Luciano Rezzolla and Michael Kramer and the partner institutes are JIVE, IRAM, MPE Garching, IRA/INAF Bologna, SKA and ESO. BlackHoleCam is part of the Event Horizon Telescope collaboration.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/24/2021 02:28 pm
First M87 Event Horizon Telescope Results. VII. Polarization of the Ring

Abstract
In 2017 April, the Event Horizon Telescope (EHT) observed the near-horizon region around the supermassive black hole at the core of the M87 galaxy. These 1.3 mm wavelength observations revealed a compact asymmetric ring-like source morphology. This structure originates from synchrotron emission produced by relativistic plasma located in the immediate vicinity of the black hole. Here we present the corresponding linear-polarimetric EHT images of the center of M87. We find that only a part of the ring is significantly polarized. The resolved fractional linear polarization has a maximum located in the southwest part of the ring, where it rises to the level of ~15%. The polarization position angles are arranged in a nearly azimuthal pattern. We perform quantitative measurements of relevant polarimetric properties of the compact emission and find evidence for the temporal evolution of the polarized source structure over one week of EHT observations. The details of the polarimetric data reduction and calibration methodology are provided. We carry out the data analysis using multiple independent imaging and modeling techniques, each of which is validated against a suite of synthetic data sets. The gross polarimetric structure and its apparent evolution with time are insensitive to the method used to reconstruct the image. These polarimetric images carry information about the structure of the magnetic fields responsible for the synchrotron emission. Their physical interpretation is discussed in an accompanying publication.

https://iopscience.iop.org/article/10.3847/2041-8213/abe71d
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/24/2021 02:31 pm
First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon

Abstract
Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EHT, along with simultaneous unresolved observations with the Atacama Large Millimeter/submillimeter Array, to expectations from theoretical models. The low fractional linear polarization in the resolved image suggests that the polarization is scrambled on scales smaller than the EHT beam, which we attribute to Faraday rotation internal to the emission region. We estimate the average density ne ~ 104–7 cm−3, magnetic field strength B ~ 1–30 G, and electron temperature Te ~ (1–12) × 1010 K of the radiating plasma in a simple one-zone emission model. We show that the net azimuthal linear polarization pattern may result from organized, poloidal magnetic fields in the emission region. In a quantitative comparison with a large library of simulated polarimetric images from general relativistic magnetohydrodynamic (GRMHD) simulations, we identify a subset of physical models that can explain critical features of the polarimetric EHT observations while producing a relativistic jet of sufficient power. The consistent GRMHD models are all of magnetically arrested accretion disks, where near-horizon magnetic fields are dynamically important. We use the models to infer a mass accretion rate onto the black hole in M87 of (3–20) × 10−4 M⊙ yr−1.

https://iopscience.iop.org/article/10.3847/2041-8213/abe4de
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/25/2021 06:59 pm
To help answer this question would be if we could get samples back from the Moon’s South Pole.

Remains of impact that created the Moon may lie deep within Earth

Quote
Desch says the team could test its idea by looking for geochemical similarities between the island lavas and rocks from the Moon’s mantle. None of the Apollo samples capture the unaltered mantle, which is one reason scientists want samples from the Moon’s largest impact crater, on its south pole, where such rocks may be exhumed. NASA and China are both planning robotic missions to the south pole this decade, and it is a leading candidate site for NASA’s return of astronauts to the Moon.

https://www.sciencemag.org/news/2021/03/remains-impact-created-moon-may-lie-deep-within-earth
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/27/2021 04:41 pm
You can put away your tin hats at least for now.

https://www.nasa.gov/feature/jpl/nasa-analysis-earth-is-safe-from-asteroid-apophis-for-100-plus-years

https://youtu.be/hjJIyZKbHqc
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/29/2021 09:27 pm
Possible discovery of the first intermediate mass black hole.

Quote
Summary:
Scientists discover one of the first black holes of its kind. Intermediate mass black holes (100 to 100,000 times the mass of the sun) have only been directly detected once before (LIGO, last year). They form an important link between the smaller black holes left behind after the deaths of stars, and the supermassive black holes which lurk in the hearts of every galaxy. The astrophysicists also find that there are about 40,000 of these objects in the neighbourhood of our galaxy.

https://www.sciencedaily.com/releases/2021/03/210329122904.htm
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/31/2021 07:01 pm
Dark energy may not exist and it’s all dark matter.

Consistency analysis of a Dark Matter velocity dependent force as an alternative to the Cosmological Constant

A range of cosmological observations demonstrate an accelerated expansion of the Universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is relevant to investigate alternative models. This article uses numerical simulations to test the consistency of one such alternative model. Specifically, this model has no cosmological constant, instead the dark matter particles have an extra force proportional to velocity squared, somewhat reminiscent of the magnetic force in electrodynamics. The constant strength of the force is the only free parameter. Since bottom-up structure formation creates cosmological structures whose internal velocity dispersions increase in time, this model may mimic the temporal evolution of the effect from a cosmological constant. It is shown that models with force linearly proportional to internal velocites, or models proportional to velocity to power three or more cannot mimic the accelerated expansion induced by a cosmological constant. However, models proportional to velocity squared are still consistent with the temporal evolution of a Universe with a cosmological model.

https://arxiv.org/abs/2102.07792

https://phys.org/news/2021-03-composition-percent-universe.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/31/2021 07:09 pm
Fluid-like elastic response of superionic NH3 in Uranus and Neptune

Significance

H2O and NH3 are representative materials comprising the mantle of ice giant planets. While H2O probably exists as the superionic state, in which hydrogen rapidly diffuses through oxygen sublattices, in the deep mantle of Uranus and Neptune, the stability field and physical properties of the superionic phase of NH3 are poorly understood. Our Brillouin study for NH3 suggested a new superionic phase exhibiting a longitudinal wave velocity comparable to that of the liquid, which is stable in the mantle of Uranus and Neptune at pressures higher than ∼50 GPa. We suggest that the superionic NH3 is nonviscous and thus cannot contribute to the internal stratification responsible for generation of the nondipolar magnetic fields observed at the icy planets.

https://www.pnas.org/content/118/14/e2021810118

https://phys.org/news/2021-03-strange-planets-neptune-uranus-mysterious.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/01/2021 09:00 pm
Interview with Dr. Brian Keating and his hunt for  Lorentz Invariance Violation:

https://youtu.be/UnMCpyIfmgM
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/04/2021 02:50 pm
https://www.sciencealert.com/an-exploding-star-65-light-years-away-from-earth-may-have-triggered-a-mass-extinction

Related paper:

Supernova triggers for end-Devonian extinctions

https://www.pnas.org/content/117/35/21008
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/05/2021 04:31 pm
Quote
A new study shows a correlation between the end of solar cycles and a switch from El Nino to La Nina conditions in the Pacific Ocean, suggesting that solar variability can drive seasonal weather variability on Earth.


If the connection outlined in the journal Earth and Space Science holds up, it could significantly improve the predictability of the largest El Nino and La Nina events, which have a number of seasonal climate effects over land. For example, the southern United States tends to be warmer and drier during a La Nina, while the northern U.S. tends to be colder and wetter.

Quote
The paper does not delve into what physical connection between the Sun and Earth could be responsible for the correlation, but the authors note that there are several possibilities that warrant further study, including the influence of the Sun's magnetic field on the amount of cosmic rays that escape into the solar system and ultimately bombard Earth. However, a robust physical link between cosmic rays variations and climate has yet to be determined.

"If further research can establish that there is a physical connection and that changes on the Sun are truly causing variability in the oceans, then we may be able to improve our ability to predict El Nino and La Nina events," McIntosh said.

https://phys.org/news/2021-04-ties-solar-variability-onset-decadal.html

Related paper:

Termination of Solar Cycles and Correlated Tropospheric Variability

Abstract

The Sun provides the energy required to sustain life on Earth and drive our planet's atmospheric circulation. However, establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge. The canon of solar variability is derived from the 400 years of observations that demonstrates the waxing and waning number of sunspots over an 11(‐ish) year period. Recent research has demonstrated the significance of the underlying 22 years magnetic polarity cycle in establishing the shorter sunspot cycle. Integral to the manifestation of the latter is the spatiotemporal overlapping and migration of oppositely polarized magnetic bands. We demonstrate the impact of “terminators”—the end of Hale magnetic cycles—on the Sun's radiative output and particulate shielding of our atmosphere through the rapid global reconfiguration of solar magnetism. Using direct observation and proxies of solar activity going back some six decades we can, with high statistical significance, demonstrate a correlation between the occurrence of terminators and the largest swings of Earth's oceanic indices: the transition from El Niño to La Niña states of the central Pacific. This empirical relationship is a potential source of increased predictive skill for the understanding of El Niño climate variations, a high‐stakes societal imperative given that El Niño impacts lives, property, and economic activity around the globe. A forecast of the Sun's global behavior places the next solar cycle termination in mid‐2020; should a major oceanic swing follow, then the challenge becomes: when does correlation become causation and how does the process work?

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EA001223
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/07/2021 07:01 pm
After the recent LHC results it’s another example of a challenge to the standard model by the behaviour of Muons.

Quote
In a landmark experiment, scientists have found fresh evidence that a subatomic particle is disobeying one of science’s most watertight theories, the Standard Model of particle physics. The gap between the model’s predictions and the particle’s newly measured behavior hints that the universe may contain unseen particles and forces beyond our current grasp.

In a seminar on Wednesday, researchers with Fermilab in Batavia, Illinois, announced the first results of the Muon g-2 experiment, which since 2018 has measured a particle called the muon, a heavier sibling of the electron that was discovered in the 1930s.

https://www.nationalgeographic.com/science/article/ultra-precise-experiment-finds-hints-of-unseen-particles-in-the-universe
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 04/07/2021 07:23 pm
Although we should bear in mind that this behaviour might not be unpredicted by the Standard Model at all. The team's models for how much muons should wobble according to the Standard Model do not include the latest theoretical results, which suggests it is more than previously found. This article explains fairly well;

https://www.quantamagazine.org/muon-g-2-experiment-at-fermilab-finds-hint-of-new-particles-20210407

Quote
Today’s long-anticipated announcement by Fermilab’s Muon g-2 team appears to solidify a tantalizing conflict between nature and theory. But a separate calculation, published at the same time, has clouded the picture.

Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/07/2021 09:31 pm
Although we should bear in mind that this behaviour might not be unpredicted by the Standard Model at all. The team's models for how much muons should wobble according to the Standard Model do not include the latest theoretical results, which suggests it is more than previously found. This article explains fairly well;

https://www.quantamagazine.org/muon-g-2-experiment-at-fermilab-finds-hint-of-new-particles-20210407

Quote
Today’s long-anticipated announcement by Fermilab’s Muon g-2 team appears to solidify a tantalizing conflict between nature and theory. But a separate calculation, published at the same time, has clouded the picture.
This is confusing as the article I posted said that the team concerned had also calculated the theoretical wobble for the Muon to an unprecedented level beyond what any other group had ever achieved based on years of real data. There doesn’t appear to be anything to suggest why this alternative theoretical driven model should be preferred to one based on actual data collection.
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 04/07/2021 09:43 pm
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/07/2021 09:46 pm
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
I don’t see as I said above why this model should be preferred to one based on actual data?
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 04/07/2021 09:54 pm
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
I don’t see as I said above why this model should be preferred to one based on actual data?

What model based on actual data?

Both teams are relying on theoretical models of Standard Model interactions to compare the observations with. They differ as to what the theory predicts should happen.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/08/2021 09:03 am
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
I don’t see as I said above why this model should be preferred to one based on actual data?

What model based on actual data?

Both teams are relying on theoretical models of Standard Model interactions to compare the observations with. They differ as to what the theory predicts should happen.
But unless I am misreading it isn’t one weighted more towards the use of past data in its prediction compared to the other?
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 04/08/2021 09:04 am
A graphical explanation:

https://twitter.com/Resonaances/status/1379924035421753350/photo/1 (https://twitter.com/Resonaances/status/1379924035421753350/photo/1)

 :)
NB: Some "nitpicking" comments that build on the above: " What you quote as "lattice" is only BMW collaboration result. There are lattice results in the green (mint?) average. - Correct, in this plot "lattice" is just BMW and reality is a bit more subtle. However, other lattice results have similar central values as BMW, just larger errors, so they do not change the picture qualitatively.".
Bottom line:
If lattice is correct, the difference between the theory and experiment is currently too small to be exciting.
Some more context from just-post-announcement reactions:
https://twitter.com/Resonaances/status/1379831945740292099
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 04/08/2021 10:05 am
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
I don’t see as I said above why this model should be preferred to one based on actual data?

What model based on actual data?

Both teams are relying on theoretical models of Standard Model interactions to compare the observations with. They differ as to what the theory predicts should happen.
But unless I am misreading it isn’t one weighted more towards the use of past data in its prediction compared to the other?

There is no actual data for the interaction in question. The 'data driven' theory is based on equating another type of interaction (electron scattering) with the one in question and assuming empirical data from that interaction also applies to this one. So for the value we need to know It's still just theoretical guesswork. It relies on the theory used to equate the interactions being correct.

Edit: I see Jester has just written a blog post about it;

http://resonaances.blogspot.com/2021/04/why-is-it-when-something-happens-it-is.html
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/08/2021 02:31 pm
It is mentioned further down the NatGeo article, though a bit more glossed over than it should have been,

Quote
Theorists also are beginning to poke and prod at the Standard Model’s prediction, especially the parts that are notoriously tricky to calculate. New supercomputer methods called lattice simulations should help, but early results disagree slightly with some of the values that El-Khadra’s team included in its theoretical calculation. It will take years to sift through these subtle differences and see how they affect the hunt for new physics.
I don’t see as I said above why this model should be preferred to one based on actual data?

What model based on actual data?

Both teams are relying on theoretical models of Standard Model interactions to compare the observations with. They differ as to what the theory predicts should happen.
But unless I am misreading it isn’t one weighted more towards the use of past data in its prediction compared to the other?

There is no actual data for the interaction in question. The 'data driven' theory is based on equating another type of interaction (electron scattering) with the one in question and assuming empirical data from that interaction also applies to this one. So for the value we need to know It's still just theoretical guesswork. It relies on the theory used to equate the interactions being correct.

Edit: I see Jester has just written a blog post about it;

http://resonaances.blogspot.com/2021/04/why-is-it-when-something-happens-it-is.html
Thank you for that explanation and the blog post link. I have to admit the maths discussed on that link is well above my maths understanding.

Would even more powerful supercomputers like the one that’s just coming online in Japan help much with the theoretical modelling accuracy?

Fermilab video:

https://youtu.be/ZjnK5exNhZ0
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/08/2021 02:45 pm
Five carbon- and nitrogen-bearing species in a hot giant planet’s atmosphere

Abstract
The atmospheres of gaseous giant exoplanets orbiting close to their parent stars (hot Jupiters) have been probed for nearly two decades1,2. They allow us to investigate the chemical and physical properties of planetary atmospheres under extreme irradiation conditions3. Previous observations of hot Jupiters as they transit in front of their host stars have revealed the frequent presence of water vapour4 and carbon monoxide5 in their atmospheres; this has been studied in terms of scaled solar composition6 under the usual assumption of chemical equilibrium. Both molecules as well as hydrogen cyanide were found in the atmosphere of HD 209458b5,7,8, a well studied hot Jupiter (with equilibrium temperature around 1,500 kelvin), whereas ammonia was tentatively detected there9 and subsequently refuted10. Here we report observations of HD 209458b that indicate the presence of water (H2O), carbon monoxide (CO), hydrogen cyanide (HCN), methane (CH4), ammonia (NH3) and acetylene (C2H2), with statistical significance of 5.3 to 9.9 standard deviations per molecule. Atmospheric models in radiative and chemical equilibrium that account for the detected species indicate a carbon-rich chemistry with a carbon-to-oxygen ratio close to or greater than 1, higher than the solar value (0.55). According to existing models relating the atmospheric chemistry to planet formation and migration scenarios3,11,12, this would suggest that HD 209458b formed far from its present location and subsequently migrated inwards11,13. Other hot Jupiters may also show a richer chemistry than has been previously found, which would bring into question the frequently made assumption that they have solar-like and oxygen-rich compositions.

https://www.nature.com/articles/s41586-021-03381-x
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/08/2021 03:02 pm
Ancient Earth was a water world

Summary
Over time, sea levels have risen and fallen with temperatures—but Earth's total surface water was always assumed to be constant. Now, evidence is mounting that some 3 billion to 4 billion years ago, the planet's oceans held nearly twice as much water—enough to submerge today's continents. Rocks in today's mantle, the thick layer beneath the crust, are thought to sequester an ocean's worth of water or more in their mineral structures. But early in Earth's history, the mantle, warmed by radioactivity, was four times hotter. Work using hydraulic presses has shown that many minerals would be unable to hold as much hydrogen and oxygen at mantle temperatures and pressures. A new model of the mantle's evolution through time, based on these results, suggests the mantle could have held far less water in the past. And the most likely home for that water was the surface. This flood could have primed the engine of plate tectonics and made it more difficult for life to start on land.

https://science.sciencemag.org/content/371/6534/1088
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/19/2021 02:23 pm
Discovery of a directly imaged planet to the young solar analog YSES 2

Abstract
Context. To understand the origin and formation pathway of wide-orbit gas giant planets, it is necessary to expand the limited sample of these objects. The mass of exoplanets derived with spectrophotometry, however, varies strongly as a function of the age of the system and the mass of the primary star.
Aims. By selecting stars with similar ages and masses, the Young Suns Exoplanet Survey (YSES) aims to detect and characterize planetary-mass companions to solar-type host stars in the Scorpius-Centaurus association.
Methods. Our survey is carried out with VLT/SPHERE with short exposure sequences on the order of 5 min per star per filter. The subtraction of the stellar point spread function (PSF) is based on reference star differential imaging using the other targets (with similar colors and magnitudes) in the survey in combination with principal component analysis. Two astrometric epochs that are separated by more than one year are used to confirm co-moving companions by proper motion analysis.
Results. We report the discovery of YSES 2b, a co-moving, planetary-mass companion to the K1 star YSES 2 (TYC 8984-2245-1, 2MASS J11275535-6626046). The primary has a Gaia EDR3 distance of 110 pc, and we derive a revised mass of 1.1 M⊙ and an age of approximately 14 Myr. We detect the companion in two observing epochs southwest of the star at a position angle of 205° and with a separation of ~1.′′05, which translates to a minimum physical separation of 115 au at the distance of the system. Photometric measurements in the H and Ks bands are indicative of a late L spectral type, similar to the innermost planets around HR 8799. We derive a photometric planet mass of 6.3−0.9+1.6 MJup using AMES-COND and AMES-dusty evolutionary models; this mass corresponds to a mass ratio of q = (0.5 ± 0.1)% with the primary. This is the lowest mass ratio of a direct imaging planet around a solar-type star to date. We discuss potential formation mechanisms and find that the current position of the planet is compatible with formation by disk gravitational instability, but its mass is lower than expected from numerical simulations. Formation via core accretion must have occurred closer to the star, yet we do not find evidence that supports the required outward migration, such as via scattering off another undiscovered companion in the system. We can exclude additional companions with masses greater than 13 MJup in the full field of view of the detector (0.′′15<ρ<5.′′50), at 0.′′5 we can rule out further objects that are more massive than 6 MJup, and for projected separations ρ >2′′ we are sensitive to planets with masses as low as 2 MJup.
Conclusions. YSES 2b is an ideal target for follow-up observations to further the understanding of the physical and chemical formation mechanisms of wide-orbit Jovian planets. The YSES strategy of short snapshot observations (≤5 min) and PSF subtraction based on a large reference library proves to be extremely efficient and should be considered for future direct imaging surveys.

https://www.aanda.org/articles/aa/full_html/2021/04/aa40508-21/aa40508-21.html

Source: https://phys.org/news/2021-04-giant-planet-large-distance-sun-like.html
Title: Re: Astronomy & Planetary Science Thread
Post by: sghill on 04/20/2021 02:38 am
I have a question for any experts who can educate me:

This Hubble image from 2012 of Hurcules A's black hole jets has been trending for some reason lately.

Could this be an image of jets from a "white hole" and not accretion disk jets from a super massive black hole?

https://hubblesite.org/contents/news-releases/2012/news-2012-47.html#section-id-2
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/20/2021 10:06 am
Article on Primordial Black Holes and their possible connection to Dark Matter.

https://www.pbs.org/newshour/science/primordial-black-holes-could-explain-dark-matter-galaxy-growth-and-more
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 04/20/2021 08:57 pm
Could this be an image of jets from a "white hole" and not accretion disk jets from a super massive black hole?

I believe a white hole would radiate particles etc uniformly in all directions.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/21/2021 07:04 pm
Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through Far-ultraviolet Observations

Abstract
We present the discovery of an extreme flaring event from Proxima Cen by the Australian Square Kilometre Array Pathfinder (ASKAP), Atacama Large Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST), Transiting Exoplanet Survey Satellite (TESS), and the du Pont Telescope that occurred on 2019 May 1. In the millimeter and FUV, this flare is the brightest ever detected, brightening by a factor of &gt;1000 and &gt;14,000 as seen by ALMA and HST, respectively. The millimeter and FUV continuum emission trace each other closely during the flare, suggesting that millimeter emission could serve as a proxy for FUV emission from stellar flares and become a powerful new tool to constrain the high-energy radiation environment of exoplanets. Surprisingly, optical emission associated with the event peaks at a much lower level with a time delay. The initial burst has an extremely short duration, lasting for &lt;10 s. Taken together with the growing sample of millimeter M dwarf flares, this event suggests that millimeter emission is actually common during stellar flares and often originates from short burst-like events.

https://iopscience.iop.org/article/10.3847/2041-8213/abf14c

Source: https://phys.org/news/2021-04-humungous-flare-sun-nearest-neighbor.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/23/2021 10:12 am
Evidence that Ultra-high-energy Gamma Rays Are a Universal Feature near Powerful Pulsars

Abstract
The highest-energy known gamma-ray sources are all located within 0fdg5 of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; &gt;56 TeV) gamma-ray emission is a universal feature expected near pulsars with a high spin-down power. Using four years of data from the High Altitude Water Cherenkov Gamma-Ray Observatory, we present a joint-likelihood analysis of 10 extremely powerful pulsars to search for subthreshold UHE gamma-ray emission correlated with these locations. We report a significant detection (&gt;3σ), indicating that UHE gamma-ray emission is a generic feature of powerful pulsars. We discuss the emission mechanisms of the gamma rays and the implications of this result. The individual environment, such as the magnetic field and particle density in the surrounding area, appears to play a role in the amount of emission.

https://iopscience.iop.org/article/10.3847/2041-8213/abf4dc

Source: https://phys.org/news/2021-04-ultra-high-energy-gamma-rays-pulsar-nebulae.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/23/2021 02:30 pm
Quote
An international team of researchers searched for pieces of a small asteroid tracked in space and then observed to impact Botswana on June 2, 2018. Guided by SETI Institute meteor astronomer Peter Jenniskens, they found 23 meteorites deep inside the Central Kalahari Game Reserve and now have published their findings online in the journal Meteoritics and Planetary Science.

"Combining the observations of the small asteroid in space with information gleaned from the meteorites shows it likely came from Vesta, second largest asteroid in our solar system and target of NASA's DAWN mission," said Jenniskens. "Billions of years ago, two giant impacts on Vesta created a family of larger, more dangerous asteroids. The newly recovered meteorites gave us a clue on when those impacts might have happened."

https://phys.org/news/2021-04-asteroid-botswana-vesta.html
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/25/2021 09:49 pm
Theia and The Mysterious Flash of Light at NGC 2547:

https://youtu.be/OflIp1M_zXE

Just to add unlike a lot of You Tubers he usually quotes from scientific papers, and links to them in the video description.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 04/27/2021 04:32 pm
Optical and Ultraviolet Monitoring of the Black Hole X-ray Binary MAXI J1820+070/ASASSN-18ey for 18 Months

MAXI J1820+070 is a low-mass black hole X-ray binary system with high luminosity in both optical and X-ray bands during the outburst periods. We present extensive photometry in X-ray, ultraviolet, and optical bands, as well as densely-cadenced optical spectra, covering the phase from the beginning of optical outburst to ∼550 days. During the rebrightening process, the optical emission preceded the X-ray by 20.80 ± 2.85 days. The spectra are characterized by blue continua and emission features of Balmer series, He I, He II lines and broad Bowen blend. The pseudo equivalent width (pEW) of emission lines are found to show anticorrelations with the X-ray flux measured at comparable phases, which is due to the increased suppression by the optical continuum. At around the X-ray peak, the full width at half maximums (FWHMs) of Hβ and He II λ4686 tend to stabilize at 19.4 Angstrom and 21.8 Angstrom, which corresponds to the line forming region at a radius of 1.7 and 1.3 R_sun within the disk. We further analyzed the absolute fluxes of the lines and found that the fluxes of Hβ and He II λ4686 show positive correlations with the X-ray flux, favoring that the irradiation model is responsible for the optical emission. However, the fact that X-ray emission experiences a dramatic flux drop at t∼200 days after the outburst, while the optical flux only shows little variations suggests that additional energy such as viscous energy may contribute to the optical radiation in addition to the X-ray irradiation.

https://arxiv.org/abs/2104.10370

Source: https://phys.org/news/2021-04-chinese-astronomers-black-hole-x-ray.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/29/2021 09:46 am
Constraints on the antistar fraction in the Solar System neighborhood from the 10-year Fermi Large Area Telescope gamma-ray source catalog

ABSTRACT
It is generally taken for granted that our Universe is free of antimatter objects and domains. This certitude has recently been challenged by the possible detection of antihelium nuclei by AMS-02. Should the observation be confirmed, the existence of nearby antistars would make a plausible hypothesis to explain the origin of the antinuclei. In this paper, we use the 10-year Fermi Large Area Telescope (LAT) gamma-ray source catalog to set constraints on the abundance of antistars around the Sun. We identify in the catalog 14 antistar candidates not associated with any objects belonging to established gamma-ray source classes and with a spectrum compatible with baryon-antibaryon annihilation. We use them along with an estimate of the LAT sensitivity to antistars to set upper limits on the local antistar fraction
f
¯

 with respect to normal stars. We provide parametric limits as a function of the closest antistar mass, velocity, and surrounding matter density. We also employ a novel Monte Carlo method to set limits for a few hypotheses about the antistar population. For a population with properties equivalent to those of regular stars concentrated in the Galactic disk, we obtain
f
¯

<
2.5
×
10

6
 at 95% confidence level, which is 20 times more constraining than limits previously available. For a primordial population of antistars distributed in the Galactic halo, we obtain new local upper limits which decrease as a function of antistar mass
M
from
f
¯

<
0.2
 at 95% confidence level for
M
=
1


M

 to
f
¯

<
1.6
×
10

4
 at 95% confidence level for
M
=
10


M

. By combining these limits with existing microlensing constraints for lighter objects in the Magellanic Clouds, we infer that a primordial population of halo antistars must have a density lower than
O
(
10

5


pc

3
)
 to
O
(
10

2


pc

3
)
 depending on their masses. Our limits can constrain models for the origin and propagation of antinuclei in cosmic rays.

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.083016

Source: https://www.sciencealert.com/these-14-milky-way-objects-could-be-stars-made-of-antimatter
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/03/2021 08:47 am
Quote
Why the renewed focus on astrometry when it comes to Alpha Centauri (a theme we saw as well in the previous post on ALMA observations from the surface)? One problem we face with other detection methods is simply statistical: We can study planets, as via the Kepler mission, by their transits, but if we want to know about specific stars that are near us, we can’t assume a lucky alignment.

Radial velocity requires no transits, but has yet to be pushed to the level of detecting Earth-mass planets at habitable-zone distances from stars like our own. This is why imaging is now very much in the mix, as is astrometry, and getting the latter into space in a dedicated mission has occupied a team at the University of Sydney led by Peter Tuthill for a number of years — I remember hearing Tuthill describe the technology at Breakthrough Discuss in 2016.

Out of this effort we get a concept called TOLIMAN, a space telescope that draws its title from Alpha Centauri B, whose medieval name in Arabic, so I’m told, was al-Zulmn. [Addendum: This is mistaken, as reader Joy Sutton notes in the comments. It wouldn’t be until well after the medieval period — in 1689 — that the binary nature of Centauri A and B was discovered by Jesuit missionary and astronomer Jean Richaud. The name al-Zulmn seems to be associated with an asterism that included Alpha Centauri, though I haven’t been able to track down anything more about it. Will do some further digging.]

More about this proposed mission on the link below.

https://www.centauri-dreams.org/2021/04/30/toliman-looking-for-earth-mass-planets-at-alpha-centauri/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/06/2021 02:25 pm
'Oddball supernova' reveals star's death throes before exploding

https://edition.cnn.com/2021/05/05/world/yellow-star-odd-supernova-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/06/2021 02:25 pm
'Oddball supernova' reveals star's death throes before exploding

https://edition.cnn.com/2021/05/05/world/yellow-star-odd-supernova-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/07/2021 07:56 pm
The Solar Wind: A Heliophysics Sea Shanty (The Wellerman parody):

https://youtu.be/LP3qzKGh1AM
Title: Re: Astronomy & Planetary Science Thread
Post by: tpw2 on 05/16/2021 06:15 am
Are the any news about the astrophysics decadal survey? The last I heard a few months ago was that the release was still planned for spring 2021, so it should happen very soon.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/17/2021 09:05 am
Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b

Recent discoveries of young exoplanets within their natal disks offer exciting opportunities to study ongoing planet formation. In particular, a planet's mass accretion rate can be constrained by observing the accretion-induced excess emission. So far, planetary accretion is only probed by the Hα line, which is then converted to a total accretion luminosity using correlations derived for stars. However, the majority of the accretion luminosity is expected to emerge from hydrogen continuum emission, and is best measured in the ultraviolet (UV). In this paper, we present HST/WFC3/UVIS F336W (UV) and F656N (Hα) high-contrast imaging observations of PDS 70. Applying a suite of novel observational techniques, we detect the planet PDS 70 b with signal-to-noise ratios of 5.3 and 7.8 in the F336W and F656N bands, respectively. This is the first time that an exoplanet has been directly imaged in the UV. Our observed Hα flux of PDS 70 b is higher by 3.5σ than the most recent published result. However, the light curve retrieved from our observations does not support greater than 30% variability in the planet's Hα emission in six epochs over a five-month timescale. We estimate a mass accretion rate of 1.4±0.2×10−8MJup/yr. Hα accounts for 36% of the total accretion luminosity. Such a high proportion of energy released in line emission suggests efficient production of Hα emission in planetary accretion, and motivates using the Hα band for searches of accreting planets. These results demonstrate HST/WFC3/UVIS's excellent high-contrast imaging performance and highlight its potential for planet formation studies.

https://arxiv.org/abs/2104.13934
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/17/2021 02:59 pm
Brightest cosmic light detected on Tibetan Plateau may help rewrite laws of physics

https://www.scmp.com/news/china/diplomacy/article/3133829/brightest-cosmic-light-detected-tibetan-plateau-may-help
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 05/21/2021 10:50 am
The radius of PSR J0740+6620 from NICER and XMM-Newton data

https://arxiv.org/abs/2105.06979

PSR J0740+6620 has a gravitational mass of 2.08±0.07 M⊙, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740+6620 is 13.7+2.6−1.5 km (68%). We apply our measurement, combined with the previous NICER mass and radius measurement of PSR J0030+0451, the masses of two other ∼2 M⊙ pulsars, and the tidal deformability constraints from two gravitational wave events, to three different frameworks for equation of state modeling, and find consistent results at ∼1.5−3 times nuclear saturation density. For a given framework, when all measurements are included the radius of a 1.4 M⊙ neutron star is known to ±4% (68% credibility) and the radius of a 2.08 M⊙ neutron star is known to ±5%. The full radius range that spans the ±1σ credible intervals of all the radius estimates in the three frameworks is 12.45±0.65 km for a 1.4 M⊙ neutron star and 12.35±0.75 km for a 2.08 M⊙ neutron star.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/21/2021 04:18 pm
Atomic-scale mixing between MgO and H2O in the deep interiors of water-rich planets

Abstract
Water-rich planets exist in our Solar System (Uranus and Neptune) and are found to be common in the extrasolar systems (some of the sub-Neptunes). In conventional models of these planets a thick water-rich layer is underlain by a separate rocky interior. Here we report experimental results on two rock-forming minerals, olivine ((Mg,Fe)2SiO4) and ferropericlase ((Mg,Fe)O), in water at the pressure and temperature conditions expected for the water-rich planets. Our data indicate a selective leaching of MgO, which peaks between 20 and 40 GPa and above 1,500 K. For water-rich planets with 1–6 Earth masses (>50 wt% H2O), the chemical reaction at the deep water–rock interface would lead to high concentrations of MgO in the H2O layer. For Uranus and Neptune, the top ~3% of the H2O layer would have a large storage capacity for MgO. If an early dynamic process enables the rock–H2O reaction, the topmost H2O layer may be rich in MgO, possibly affecting the thermal history of the planet.

https://www.nature.com/articles/s41550-021-01368-2
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2021 10:52 am
Heavy metal vapours unexpectedly found in comets throughout our Solar System — and beyond

A new study by a Belgian team using data from the European Southern Observatory’s Very Large Telescope (ESO’s VLT) has shown that iron and nickel exist in the atmospheres of comets throughout our Solar System, even those far from the Sun. A separate study by a Polish team, who also used ESO data, reported that nickel vapour is also present in the icy interstellar comet 2I/Borisov. This is the first time heavy metals, usually associated with hot environments, have been found in the cold atmospheres of distant comets.

https://www.eso.org/public/news/eso2108/

The two related papers:

https://www.nature.com/articles/s41586-021-03435-0

https://www.nature.com/articles/s41586-021-03485-4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/25/2021 10:39 am
Anomalous diffusion across a tera-Gauss magnetic field in accreting neutron stars

Abstract

When mass falls on the polar regions of a neutron star in a binary X-ray source system, it tends to spread out over the entire surface. A long-standing question in research on this problem is: will the mass be anchored on the magnetic field lines and drag the field with it or is there a special mechanism that allows the mass to slip through the magnetic field lines, leading to much less distortion? As the amount of mass falling on the neutron star can actually be comparable with the neutron star mass, the question of which alternative holds is very important. We suggest an efficient mechanism that will allow the mass to slip through the lines. The mechanism is based on a strong ideal Schwarzschild (Structure and Evolution of the Stars. Princeton University Press, 1958) instability. As the instability itself is ideal, it cannot directly force the mass to slip though the lines. However, it can create a cascade of eddies whose scale extends down to a resistive scale, at the same time mixing the field lines up without breaking them. On this scale the mass can cross the lines. This instability is efficient enough that it can produce a mass flow in the plasma without growing to a large amplitude but saturates at a small one. The instability determines the mass per flux distribution of the accumulated material on different lines so that the equilibrium is marginal to the instability on every line. This makes the equilibrium unique. Thus, as the extra mass on the neutron star grows, the state of the outer shell proceeds through a sequence of unique critically unstable equilibria. In an appendix, an attempt is made to track the critical equilibria over long times.

https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/anomalous-diffusion-across-a-teragauss-magnetic-field-in-accreting-neutron-stars/286039FE28ACDF79CF9EBE55E814A72E#

Source: https://www.sciencealert.com/this-could-be-how-plasma-breaks-through-a-neutron-star-s-insane-magnetic-field
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/25/2021 10:49 am
https://www.cnet.com/news/major-burst-of-solar-flares-could-trigger-bright-auroras-this-week/

https://twitter.com/CarolynKennett/status/1396747876529807361

Quote
Loving this video from NASA's SDO, the sun has woken from its slumber and at the weekend sunspot AR2824 sent out 2 large flares and 10 smaller ones, as they reach Earth on Wednesday there may be aurora. #astronomy #watchingthesun
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/27/2021 07:12 pm
The results cause possible issues with current theories.

New dark matter map reveals cosmic mystery

https://www.bbc.co.uk/news/science-environment-57244708
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/27/2021 07:28 pm
Natural Plutonium Discovered Beneath The Oceans Shows Cataclysmic History:

https://youtu.be/c-B3UVGVCmU
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/27/2021 09:30 pm
Mysterious radio burst from space is unusually close—and especially baffling

https://www.nationalgeographic.com/science/article/mysterious-radio-burst-from-space-is-unusually-close-and-especially-baffling

Related paper:

https://arxiv.org/pdf/2105.11445.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/31/2021 04:36 pm
The newborn black hole in GRB 191014C proves that it is alive

Abstract
A multi-decade theoretical effort has been devoted to finding an efficient mechanism to use the rotational and electrodynamical extractable energy of a Kerr-Newman black hole (BH), to power the most energetic astrophysical sources such as gamma-ray bursts (GRBs) and active galactic nuclei. We show an efficient general relativistic electrodynamical process which occurs in the “inner engine” of a binary driven hypernova. The inner engine is composed of a rotating Kerr BH of mass M and dimensionless spin parameter α, a magnetic field of strength B0 aligned and parallel to the rotation axis, and a very low-density ionized plasma. Here, we show that the gravitomagnetic interaction between the BH and the magnetic field induces an electric field that accelerates electrons and protons from the environment to ultrarelativistic energies emitting synchrotron radiation. We show that in GRB 190114C the BH of mass M=4.4M, α=0.4, and B0≈4×1010 G can lead to a high-energy (GeV) luminosity of 1051 erg s−1. The inner engine parameters are determined by requiring (1) that the BH extractable energy explains the GeV and ultrahigh-energy emission energetics, (2) that the emitted photons are not subjected to magnetic-pair production, and (3) that the synchrotron radiation timescale agrees with the observed high-energy timescale. We find for GRB 190114C a clear jetted emission of GeV energies with a semi-aperture angle of approximately 60° with respect to the BH rotation axis.

https://www.aanda.org/articles/aa/full_html/2021/05/aa37135-19/aa37135-19.html

Source: https://www.sciencealert.com/new-evidence-suggests-rotational-energy-can-be-extracted-from-the-event-horizon-of-a-black-hole
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/01/2021 04:42 pm
Neutron stars may be quite a bit bigger than previously though:

https://www.syfy.com/syfywire/neutron-stars-may-be-quite-a-bit-bigger-than-previously-thought
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/02/2021 02:52 pm
Identification of an [α/Fe]—Enhanced Thick Disk Component in an Edge-on Milky Way Analog

Abstract
The Milky Way disk consists of two prominent components—a thick, alpha-rich, low-metallicity component and a thin, metal-rich, low-alpha component. External galaxies have been shown to contain thin- and thick-disk components, but whether distinct components in the [α/Fe]–[Z/H] plane exist in other Milky Way-like galaxies is not yet known. We present Very Large Telescope (VLT)—Multi Unit Spectroscopic Explorer (MUSE) observations of UGC 10738, a nearby, edge-on Milky Way-like galaxy. We demonstrate through stellar population synthesis model fitting that UGC 10738 contains alpha-rich and alpha-poor stellar populations with similar spatial distributions to the same components in the Milky Way. We discuss how the finding that external galaxies also contain chemically distinct disk components may act as a significant constraint on the formation of the Milky Way's own thin and thick disk.

https://iopscience.iop.org/article/10.3847/2041-8213/abfc57

Source: https://www.popsci.com/space/milky-way-galaxy-insights/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/02/2021 03:23 pm
Quote
Ozone depletion following the Toba eruption around 74,000 years ago compounded the ensuing volcanic winter and caused a human population bottleneck.

https://discovery.kaust.edu.sa/en/article/1123/ancient-volcanic-eruption-destroyed-the-ozone-layer%C2%A0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2021 09:37 am
Oort cloud Ecology II: The chronology of the formation of the Oort cloud

We present a chronology on the formation and early evolution of the Oort cloud, and test the sequence of events of its formation by simulating the formation process in subsequent amalgamated steps. These simulations start with the Solar system being born with planets and asteroids in a stellar cluster orbiting the Galactic center. Upon ejection from its birth environment, we continue to follow the Solar system's evolution while it sojourns the Galaxy as an isolated planetary system. We conclude that the range in semi-major axis between ∼100\,au and several ∼103\,au still bears the signatures of the Sun being born in a $\apgt 1000$\,\Msun/pc3 star cluster, and that most of the outer Oort cloud formed after the Solar system escaped. The escape, we argue, happened between ∼20\,Myr and 50\,Myr after birth of the Solar system. Today, the bulk of the material in the Oort cloud (∼70\%) originates from the region in the circumstellar disk that was located between ∼15\,au and ∼35\,au, near the current location of the ice-giants and the Centaur family of asteroids. This population is eradicated if the ice-giant planets were born in orbital resonance. Planet migration or chaotic orbital reorganization, occurring while the Solar system is still a cluster member is, according to our model, inconsistent with the presence of the Oort cloud. About half the inner Oort cloud, between 100 and 104\,au, and a quarter of the material in the outer Oort cloud $\apgt 10^4$\,au could be non-native to the Solar system but was captured from free-floating derbis in the cluster or from the circumstellar disk of other stars in the birth cluster. Characterizing this population will help us to reconstruct the Solar system's history.

https://arxiv.org/abs/2105.12816
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2021 09:44 am
How Sublimation Delays the Onset of Dusty Debris Disk Formation Around White Dwarf Stars

Although numerous white dwarf stars host dusty debris disks, the temperature distribution of these stars differs significantly from the white dwarf population as a whole. Dusty debris disks exist exclusively around white dwarfs cooler than 27,000 K. This is all the more enigmatic given that the formation processes of dusty debris disks should favor younger, hotter white dwarfs, which likely host more dynamically unstable planetary systems. Here we apply a sophisticated material sublimation model to white dwarf systems to show that these statistics are actually a natural result of the interplay of thermal and tidal forces, and show how they define the circumstellar regions where dusty debris disks can form. We demonstrate that these processes tend to prevent stability against both sublimative destruction and reaccretion into planetesimals for rocky materials until white dwarfs cool to below ~25,000-32,000 K, in agreement with the observed limit of ~27,000 K. For pure water ice, this critical temperature is less than 2,700 K (requiring a cooling age older the universe); this precludes pure water ice-rich debris disks forming through the accepted two-step mechanism. The critical temperature is size-dependent; more massive white dwarfs could potentially host dusty debris disks at warmer temperatures. Our model suggests that the location of the disks within the PG 0010+280, GD 56, GD 362, and PG 1541+651 systems are consistent with a forsterite-dominated olivine composition. We also find that very cool white dwarfs may simultaneously host multiple, independently formed dusty debris disks, consistent with observations of the LSPM J0207+3331 system.

https://arxiv.org/abs/2104.14035
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2021 02:30 pm
Two related papers:

The California Legacy Survey I. A Catalog of 177 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades

We present a high-precision radial velocity (RV) survey of 719 FGKM stars, which host 163 known exoplanets and 14 newly discovered or revised exoplanets and substellar companions. This catalog updated the orbital parameters of known exoplanets and long-period candidates, some of which have decades-longer observational baselines than they did upon initial detection. The newly discovered exoplanets range from warm sub-Neptunes and super-Earths to cold gas giants. We present the catalog sample selection criteria, as well as over 100,000 radial velocity measurements, which come from the Keck-HIRES, APF-Levy, and Lick-Hamilton spectrographs. We introduce the new RV search pipeline RVSearch that we used to generate our planet catalog, and we make it available to the public as an open-source Python package. This paper is the first study in a planned series that will measure exoplanet occurrence rates and compare exoplanet populations, including studies of giant planet occurrence beyond the water ice line, and eccentricity distributions to explore giant planet formation pathways. We have made public all radial velocities and associated data that we use in this catalog.

https://arxiv.org/abs/2105.11583

The California Legacy Survey II. Occurrence of Giant Planets Beyond the Ice line

We used high-precision radial velocity measurements of FGKM stars to determine the occurrence of giant planets as a function of orbital separation spanning 0.03-30 au. Giant planets are more prevalent at orbital distances of 1-10 au compared to orbits interior or exterior of this range. The increase in planet occurrence at ∼1 au by a factor of ∼4 is highly statistically significant. A fall-off in giant planet occurrence at larger orbital distances is favored over models with flat or increasing occurrence. We measure 14.1+2.0−1.8 giant planets per 100 stars with semi-major axes of 2-8 au and 8.9+3.0−2.4 giant planets per 100 stars in the range 8-32 au, a decrease in giant planet occurrence with increasing orbital separation that is significant at the ∼2σ level. We find that the occurrence rate of sub-Jovian planets (0.1-1 Jupiter masses) is also enhanced for 1-10 au orbits. This suggests that lower mass planets may share the formation or migration mechanisms that drive the increased prevalence near the water-ice line for their Jovian counterparts. Our measurements of cold gas giant occurrence are consistent with the latest results from direct imaging surveys and gravitational lensing surveys despite different stellar samples. We corroborate previous findings that giant planet occurrence increases with stellar mass and metallicity.

https://arxiv.org/abs/2105.11584
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/09/2021 04:44 pm
CHIME has detected 535 new FRBs including 18 repeaters between 2018 and 2019. The repeaters also look different to the one off events. They occur evenly across the sky and at estimated rate of 9000 per day.

https://www.google.co.uk/amp/s/phys.org/news/2021-06-chime-telescope-mysterious-fast-radio.amp
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/11/2021 07:29 am
Quote
Astronomers have spotted a giant 'blinking' star towards the centre of the Milky Way, more than 25,000 light years away.

An international team of astronomers observed the star, VVV-WIT-08, decreasing in brightness by a factor of 30, so that it nearly disappeared from the sky. While many stars change in brightness because they pulsate or are eclipsed by another star in a binary system, it's exceptionally rare for a star to become fainter over a period of several months and then brighten again.

https://www.eurekalert.org/pub_releases/2021-06/uoc-asa060921.php

Related paper:

VVV-WIT-08: the giant star that blinked

We report the serendipitous discovery of a late-type giant star that exhibited a smooth, eclipse-like drop in flux to a depth of 97 per cent. Minimum flux occurred in April 2012 and the total event duration was a few hundred days. Light curves in V, I and Ks from the Optical Gravitational Lensing Experiment and VISTA Variables in the Via Lactea surveys show a remarkably achromatic event. During 17 years of observational coverage of this source only one such event was detected. The physical properties of the giant star itself appear somewhat unusual, which may ultimately provide a clue towards the nature of the system. By modelling the event as an occultation by an object that is elliptical in projection with uniform transparency, we place limits on its physical size and velocity. We find that the occultation is unlikely to be due to a chance alignment with a foreground object. We consider a number of possible candidates for the occulter, which must be optically thick and possess a radius or thickness in excess of 0.25 au. None are completely satisfactory matches to all the data. The duration, depth and relative achromaticity of the dip mark this out as an exceptionally unusual event, whose secret has still not been fully revealed. We find two further candidates in the VVV survey and we suggest that these systems, and two previously known examples, may point to a broad class of long period eclipsing binaries wherein a giant star is occulted by a circumsecondary disc.

https://arxiv.org/abs/2106.05300
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/11/2021 04:15 pm
Quote
The moons of planets that have no parent star can possess an atmosphere and retain liquid water. Astrophysicists at LMU have calculated that such systems could harbor sufficient water to make life possible – and sustain it.

https://www.lmu.de/en/newsroom/news-and-events/news/exoplanets-liquid-water-on-exomoons-of-free-floating-planets.html

Quote
Researchers from Penn’s Department of Physics and Astronomy have developed a new method for better understanding the relationship between a star’s chemical composition and planet formation.

http://penntoday.upenn.edu/news/connecting-stars-chemical-composition-and-planet-formation
Title: Re: Astronomy & Planetary Science Thread
Post by: tpw2 on 06/11/2021 07:08 pm
There's an update regarding the status of the astrophysics decadal survey: https://mailchi.mp/nas/june2021-astro2020-update?fbclid=IwAR3feM-BWc7XdF9SrOpoiXI1oGNKGCLTzQnDUJv6gD2-tfsaq7ZsGn4YUbk

The survey has only now been sent to reviewers, so it's going to take a while still. I doubt it'll be public before the autumn at the earliest.
Title: Re: Astronomy & Planetary Science Thread
Post by: tpw2 on 06/12/2021 04:12 pm
The science themes for the large-class missions of Voyage 2050 were announced yesterday: https://www.esa.int/Science_Exploration/Space_Science/Voyage_2050_sets_sail_ESA_chooses_future_science_mission_themes

They are: moons of the giant planets, galactic astronomy (exoplanets are mentioned specifically, but it could also be a mission to probe "hidden regions" of the Milky Way), and new physical probes of the early universe. To be honest, the astrophysics themes are so broad that almost any mission could be said to fall under one of them.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/19/2021 10:59 am
New Research of Impact Crater Blows Away Previous Estimates on Its Age

Quote
Scientists say the Boltysh crater in Ukraine formed well after the impact in Mexico that caused the dinosaurs to go extinct

https://www.smithsonianmag.com/science-nature/new-research-impact-crater-blows-away-previous-estimates-its-age-180978023/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/19/2021 11:06 am
Mysterious dimming of Betelgeuse was the result of star ejecting gas

Read more: https://www.newscientist.com/article/2280843-mysterious-dimming-of-betelgeuse-was-the-result-of-star-ejecting-gas/#ixzz6yEPMZP80

Related paper:

https://www.nature.com/articles/s41586-021-03546-8
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/23/2021 02:20 pm
Signs of geological activity found on Venus https://www.bbc.co.uk/news/science-environment-57567577

Here’s the related paper. It could be an analogue for early pre plate tectonic Earth.

A globally fragmented and mobile lithosphere on Venus

Abstract

Venus has been thought to possess a globally continuous lithosphere, in contrast to the mosaic of mobile tectonic plates that characterizes Earth. However, the Venus surface has been extensively deformed, and convection of the underlying mantle, possibly acting in concert with a low-strength lower crust, has been suggested as a source of some surface horizontal strains. The extent of surface mobility on Venus driven by mantle convection, however, and the style and scale of its tectonic expression have been unclear. We report a globally distributed set of crustal blocks in the Venus lowlands that show evidence for having rotated and/or moved laterally relative to one another, akin to jostling pack ice. At least some of this deformation on Venus postdates the emplacement of the locally youngest plains materials. Lithospheric stresses calculated from interior viscous flow models consistent with long-wavelength gravity and topography are sufficient to drive brittle failure in the upper Venus crust in all areas where these blocks are present, confirming that interior convective motion can provide a mechanism for driving deformation at the surface. The limited but widespread lithospheric mobility of Venus, in marked contrast to the tectonic styles indicative of a static lithosphere on Mercury, the Moon, and Mars, may offer parallels to interior–surface coupling on the early Earth, when global heat flux was substantially higher, and the lithosphere generally thinner, than today.

https://www.pnas.org/content/118/26/e2025919118
Title: Re: Astronomy & Planetary Science Thread
Post by: Vultur on 06/23/2021 07:52 pm
may offer parallels to interior–surface coupling on the early Earth, when global heat flux was substantially higher, and the lithosphere generally thinner, than today.

Huh, interesting... I remember reading that Venus didn't have plate tectonics probably because its crust was too thick...

I hope the newly approved Venus missions can give better data on what's going on.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/23/2021 08:02 pm
may offer parallels to interior–surface coupling on the early Earth, when global heat flux was substantially higher, and the lithosphere generally thinner, than today.

Huh, interesting... I remember reading that Venus didn't have plate tectonics probably because its crust was too thick...

I hope the newly approved Venus missions can give better data on what's going on.
I noted that the BBC article had a quote from someone working on the EnVision project about this paper.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/24/2021 02:27 pm
Here’s a good target for JWST.

Extremely eccentric minor planet to visit inner solar system this decade

Quote
The outskirts of our solar system is teeming with mysterious objects – and now one of them is heading our way. Astronomers have discovered a minor planet that’s about to make its closest pass to the Sun on its 600,000-year orbit.

The object in question is designated 2014 UN271, and it was only recently identified in data from the Dark Energy Survey captured between 2014 and 2018. Size estimates place it anywhere between 100 and 370 km (62 and 230 miles) wide. If it’s a comet, it’s quite a big one, especially for one coming from the outer solar system.

https://newatlas.com/space/2014-un271-comet-solar-system-close-pass/
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 06/24/2021 08:06 pm
Here’s a good target for JWST.

Extremely eccentric minor planet to visit inner solar system this decade

Quote
The outskirts of our solar system is teeming with mysterious objects – and now one of them is heading our way. Astronomers have discovered a minor planet that’s about to make its closest pass to the Sun on its 600,000-year orbit.

The object in question is designated 2014 UN271, and it was only recently identified in data from the Dark Energy Survey captured between 2014 and 2018. Size estimates place it anywhere between 100 and 370 km (62 and 230 miles) wide. If it’s a comet, it’s quite a big one, especially for one coming from the outer solar system.

https://newatlas.com/space/2014-un271-comet-solar-system-close-pass/

Just about reaching the orbit of Saturn hardly qualifies as visiting the inner solar system IMO! Still, an interesting object nonetheless.
Title: Re: Astronomy & Planetary Science Thread
Post by: Zed_Noir on 06/25/2021 07:51 am
Here’s a good target for JWST.

Extremely eccentric minor planet to visit inner solar system this decade

Quote
The outskirts of our solar system is teeming with mysterious objects – and now one of them is heading our way. Astronomers have discovered a minor planet that’s about to make its closest pass to the Sun on its 600,000-year orbit.

The object in question is designated 2014 UN271, and it was only recently identified in data from the Dark Energy Survey captured between 2014 and 2018. Size estimates place it anywhere between 100 and 370 km (62 and 230 miles) wide. If it’s a comet, it’s quite a big one, especially for one coming from the outer solar system.

https://newatlas.com/space/2014-un271-comet-solar-system-close-pass/ (https://newatlas.com/space/2014-un271-comet-solar-system-close-pass/)

Just about reaching the orbit of Saturn hardly qualifies as visiting the inner solar system IMO! Still, an interesting object nonetheless.


Maybe there is enough time to fly something to observed C/2014 UN271 up close when it fly through the Solar system orbital plane in early 2031.
Title: Re: Astronomy & Planetary Science Thread
Post by: edzieba on 06/25/2021 09:22 am
The ESA Comet Interceptor is intended for this sort of target-of-opportunity mission, but I don't know if it has the delta-V available to reach that far out or to do so in time for intercept (Comet Interceptor is expected to launch no earlier than 2029). Their documentation so far only describes mission to comets that cross nearby Earth's orbit, so likely not.
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 06/25/2021 11:11 pm
The ESA Comet Interceptor is intended for this sort of target-of-opportunity mission, but I don't know if it has the delta-V available to reach that far out or to do so in time for intercept (Comet Interceptor is expected to launch no earlier than 2029). Their documentation so far only describes mission to comets that cross nearby Earth's orbit, so likely not.

That mission immediately came to mind for me too.  It wouldn't be impossible to still do a flyby when this object passes into the solar system, and considering this thing is going to be bigger than any comet we've studied before I think it'd be worth it.  In any case, we have the luxury of ~9 years to prepare for the closeup.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/26/2021 10:23 am
By the way I’ve seen this object referred to as both a comet and minor planet for some reason which seems a bit silly calling it a minor planet considering the below.

Quote
Schwamb toned down the size estimate, saying 2014 UN271 is probably between 60 and 93 miles (100-150 km) in length, not even close to a dwarf planet in terms of size—nor is it likely to be spherical, she noted. Astronomers calculated its size by measuring the object’s reflectivity; as it gets nearer, they’ll be able to refine the size estimate even further.

Quote
That said, should the object develop a coma and tail during its perihelion in 2031, it will rank as among the largest comets ever recorded. Other examples of big comets include Comet Sarabat (observed in 1729), with an estimated nucleus around 62 miles (100 km) in diameter, and Comet Hale-Bopp, which had a nucleus from 25 to 50 miles (40 to 80 km). The newly detected object could very well be a record breaker, but we’ll have to wait for more precise size estimates to be sure.

Quote
Lawler agreed that the Vera Rubin Observatory, set to begin operations in the next year or two, will be “perfect” for monitoring the object as it nears, but she expressed some concerns about our ongoing ability to make these sorts of astronomical observations.

https://gizmodo.com/incoming-visitor-from-the-oort-cloud-could-be-among-the-1847149513
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 06/26/2021 12:17 pm
By the way I’ve seen this object referred to as both a comet and minor planet for some reason which seems a bit silly calling it a minor planet considering the below.

Quote
Schwamb toned down the size estimate, saying 2014 UN271 is probably between 60 and 93 miles (100-150 km) in length, not even close to a dwarf planet in terms of size—nor is it likely to be spherical, she noted. Astronomers calculated its size by measuring the object’s reflectivity; as it gets nearer, they’ll be able to refine the size estimate even further.

Quote
That said, should the object develop a coma and tail during its perihelion in 2031, it will rank as among the largest comets ever recorded. Other examples of big comets include Comet Sarabat (observed in 1729), with an estimated nucleus around 62 miles (100 km) in diameter, and Comet Hale-Bopp, which had a nucleus from 25 to 50 miles (40 to 80 km). The newly detected object could very well be a record breaker, but we’ll have to wait for more precise size estimates to be sure.

Quote
Lawler agreed that the Vera Rubin Observatory, set to begin operations in the next year or two, will be “perfect” for monitoring the object as it nears, but she expressed some concerns about our ongoing ability to make these sorts of astronomical observations.

https://gizmodo.com/incoming-visitor-from-the-oort-cloud-could-be-among-the-1847149513

A comet is not a comet until observed to have a coma and tail; it's an observationally-based distinction, not an intrinsic one. Until then officially it is a minor planet, even if we can guess it's likely to become a comet.
Title: Re: Astronomy & Planetary Science Thread
Post by: DreamyPickle on 06/26/2021 03:22 pm
How interesting would be it be to visit C/2016 UN271? There are many years before perihelion and it would require a mission with C3 less than New Horizons so unlikely with Oumuamua a mission is very realistic.

Are there other opportunities to visit such extremely long period comets? Intuitively the key factor would be discovering them many years before before their closest approach.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/26/2021 04:08 pm
By the way I’ve seen this object referred to as both a comet and minor planet for some reason which seems a bit silly calling it a minor planet considering the below.

Quote
Schwamb toned down the size estimate, saying 2014 UN271 is probably between 60 and 93 miles (100-150 km) in length, not even close to a dwarf planet in terms of size—nor is it likely to be spherical, she noted. Astronomers calculated its size by measuring the object’s reflectivity; as it gets nearer, they’ll be able to refine the size estimate even further.

Quote
That said, should the object develop a coma and tail during its perihelion in 2031, it will rank as among the largest comets ever recorded. Other examples of big comets include Comet Sarabat (observed in 1729), with an estimated nucleus around 62 miles (100 km) in diameter, and Comet Hale-Bopp, which had a nucleus from 25 to 50 miles (40 to 80 km). The newly detected object could very well be a record breaker, but we’ll have to wait for more precise size estimates to be sure.

Quote
Lawler agreed that the Vera Rubin Observatory, set to begin operations in the next year or two, will be “perfect” for monitoring the object as it nears, but she expressed some concerns about our ongoing ability to make these sorts of astronomical observations.

https://gizmodo.com/incoming-visitor-from-the-oort-cloud-could-be-among-the-1847149513

A comet is not a comet until observed to have a coma and tail; it's an observationally-based distinction, not an intrinsic one. Until then officially it is a minor planet, even if we can guess it's likely to become a comet.
Thanks for the clarification. It just seems odd to call an object that might be less than 100 miles in length a minor planet.
Title: Re: Astronomy & Planetary Science Thread
Post by: 192 on 06/26/2021 04:18 pm
By the way I’ve seen this object referred to as both a comet and minor planet for some reason which seems a bit silly calling it a minor planet considering the below.

Quote
Schwamb toned down the size estimate, saying 2014 UN271 is probably between 60 and 93 miles (100-150 km) in length, not even close to a dwarf planet in terms of size—nor is it likely to be spherical, she noted. Astronomers calculated its size by measuring the object’s reflectivity; as it gets nearer, they’ll be able to refine the size estimate even further.

Quote
That said, should the object develop a coma and tail during its perihelion in 2031, it will rank as among the largest comets ever recorded. Other examples of big comets include Comet Sarabat (observed in 1729), with an estimated nucleus around 62 miles (100 km) in diameter, and Comet Hale-Bopp, which had a nucleus from 25 to 50 miles (40 to 80 km). The newly detected object could very well be a record breaker, but we’ll have to wait for more precise size estimates to be sure.

Quote
Lawler agreed that the Vera Rubin Observatory, set to begin operations in the next year or two, will be “perfect” for monitoring the object as it nears, but she expressed some concerns about our ongoing ability to make these sorts of astronomical observations.

https://gizmodo.com/incoming-visitor-from-the-oort-cloud-could-be-among-the-1847149513

A comet is not a comet until observed to have a coma and tail; it's an observationally-based distinction, not an intrinsic one. Until then officially it is a minor planet, even if we can guess it's likely to become a comet.
Thanks for the clarification. It just seems odd to call an object that might be less than 100 miles in length a minor planet.

I think you're missing the context of the term minor planet here.https://en.wikipedia.org/wiki/Minor_planet (https://en.wikipedia.org/wiki/Minor_planet)

This is not the "big gravitationally rounded thing orbiting a star" sense of planet, but a more general term covering all other objects orbiting the sun other than comets. There are hundreds of thousands of minor planets.
Title: Re: Astronomy & Planetary Science Thread
Post by: punder on 06/26/2021 04:19 pm
This site says it’s officially a comet.

https://spaceweatherarchive.com/2021/06/24/huge-comet-discovery/
Title: Re: Astronomy & Planetary Science Thread
Post by: Alpha_Centauri on 06/26/2021 06:39 pm
A comet is not a comet until observed to have a coma and tail; it's an observationally-based distinction, not an intrinsic one. Until then officially it is a minor planet, even if we can guess it's likely to become a comet.
Thanks for the clarification. It just seems odd to call an object that might be less than 100 miles in length a minor planet.

Minor planet and dwarf planet are separate terms. While dwarf planet is based on an object's size, minor planet is just a catch-all term for any chunk of rock/ice not specifically classified as a comet, planet/dwarf planet or moon.

This site says it’s officially a comet.

https://spaceweatherarchive.com/2021/06/24/huge-comet-discovery/

Yeah, the latest identification of activity is the key point where a minor planet becomes reclassified a comet.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/27/2021 07:07 am
A comet is not a comet until observed to have a coma and tail; it's an observationally-based distinction, not an intrinsic one. Until then officially it is a minor planet, even if we can guess it's likely to become a comet.
Thanks for the clarification. It just seems odd to call an object that might be less than 100 miles in length a minor planet.

Minor planet and dwarf planet are separate terms. While dwarf planet is based on an object's size, minor planet is just a catch-all term for any chunk of rock/ice not specifically classified as a comet, planet/dwarf planet or moon.

This site says it’s officially a comet.

https://spaceweatherarchive.com/2021/06/24/huge-comet-discovery/

Yeah, the latest identification of activity is the key point where a minor planet becomes reclassified a comet.
Thanks I was mixing it up with the dwarf planet term, that makes a lot more sense.
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 06/27/2021 08:10 pm
Minor planet and dwarf planet are separate terms. While dwarf planet is based on an object's size, minor planet is just a catch-all term for any chunk of rock/ice not specifically classified as a comet, planet/dwarf planet or moon.

When Ceres and similar objects were first discovered they were regarded as planets because they orbited the Sun in roughly circular orbits, which was the common definition of 'planet' at the time. As more were discovered and not much was known about them, writers of astronomy books would describe the big, well-known planets in their own sections and would collect the rest in a separate section labelled 'minor planets'. As understanding progressed the consensus became that these weren't planets at all, but the term minor planet stuck.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/28/2021 04:51 pm
See ISS transit the Sun during a spacewalk in view from the Earth:

https://youtu.be/pWEmvZyFZ9Y
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/28/2021 09:24 pm
https://youtu.be/nQr2QKIR0yI
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/29/2021 11:45 am
Venus’ clouds too dry, acidic for life

https://arstechnica.com/science/2021/06/venus-clouds-too-dry-acidic-for-life/

Here’s the related paper:

https://www.nature.com/articles/s41550-021-01391-3

They also ruled out life in the Martian atmosphere and the upper atmosphere of Earth. But not some places in Jupiter’s atmosphere.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/29/2021 07:52 pm
Black holes and Neuton stars merge! 1st ever detection simulated:

https://youtu.be/vMehrzEk8oQ

Rare black hole and neutron star collisions sighted twice in 10 days https://www.bbc.co.uk/news/science-environment-57639520
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 06:38 am
An Extreme Supernova Lit The Skies 1,000 Years Ago. We May Finally Know Its Type

Quote
Based on an analysis of a more recent supernova labeled SN 2018zd, astronomers think both SN 2018zd and the 1054 CE supernova are electron-capture supernovae – a rare third type of supernova alongside type I (thermonuclear) and type II (core collapse).

Experts have hypothesized about this third type of exploding star for decades at this point, though actual physical evidence of electron-capture supernovae has been difficult to come by. The unusual characteristics of SN 2018zd – a mere 31 million light-years away – may be the first one we've actually properly identified.

https://www.sciencealert.com/this-supernova-discovery-could-help-explain-a-thousand-year-old-mystery

Here’s the related paper:

The electron-capture origin of supernova 2018zd

Abstract
In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O + Ne + Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse1,2,3,4. However, no supernovae have unequivocally been identified from an electron-capture origin, partly because of uncertainty in theoretical predictions. Here we present six indicators of electron-capture supernovae and show that supernova 2018zd is the only known supernova with strong evidence for or consistent with all six: progenitor identification, circumstellar material, chemical composition5,6,7, explosion energy, light curve and nucleosynthesis8,9,10,11,12. For supernova 2018zd, we infer a super-asymptotic giant branch progenitor based on the faint candidate in the pre-explosion images and the chemically enriched circumstellar material revealed by the early ultraviolet colours and flash spectroscopy. The light-curve morphology and nebular emission lines can be explained by the low explosion energy and neutron-rich nucleosynthesis produced in an electron-capture supernova. This identification provides insights into the complex stellar evolution, supernova physics, cosmic nucleosynthesis and remnant populations in the transitional mass range.

https://www.nature.com/articles/s41550-021-01384-2
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 09:40 am
It’s Time To Retire The Super-Earth, The Most Unsupported Idea In Exoplanets

Quote
What came as a bit of a surprise to many, however, was where that transition point occurred. Many scientists working on exoplanets — based on no physical motivation in particular — had drawn an imaginary line at about two Earth radii in their minds: below that, and you’re likely to be rocky, above that, and you’re likely to be gas-rich. The simplest way to tell, of course, would be to look at the density of your planet. In our own Solar System, the rocky planets and the gas-rich planets possess enormously different densities, so if you’re two Earth radii and still rocky, you’d expect such a planet to have about eight times the mass of Earth.

But when the data came in, it showed something remarkable: there is a transition between rocky planets and gas-rich planets, but it occurs much, much earlier, at about two Earth masses, or just 1.2 to 1.3 Earth radii. There appears to be some variety in exoplanets above that size/mass, with most of them appearing to be miniature versions of Neptune, but with a few of them, perhaps all the way up to 1.5 or even 1.6 Earth radii, still being rocky. (The majority of those, interestingly enough, are extremely hot as well.)

Quote
There is no need, and in fact it’s harmful, to remain wedded to erroneous assumptions that were made in the early days of exploring a new scientific field. As it stands today, it’s already been some ~5 years since we recognized how exoplanet populations were actually distributed; we now have PhDs who entered graduate school when it was already known that almost everything we currently call a “super-Earth” is not a rocky planet at all. Although there’s still much to learn about these exoplanets, including what’s underneath those atmospheres, we know enough about them to know which worlds are rocky and which ones are more like the gas giants we have. Based on that, now is absolutely the proper time to retire the archaic, inaccurate term, “super-Earth.”

https://www.forbes.com/sites/startswithabang/2021/06/30/its-time-to-retire-the-super-earth-the-most-unsupported-idea-in-exoplanets/?sh=1257964b5935
Title: Re: Astronomy & Planetary Science Thread
Post by: jebbo on 06/30/2021 10:02 am
The discussion on "super-Earth" was motivated by the latest CHEOPS paper about Nu2 Lupi ... and I think there's broad consensus for retiring the term.

https://arxiv.org/abs/2106.14491

There is similar discomfort with "Earth-like", which usually means "Earth-sized".

--- Tony
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 02:38 pm
Characteristics of the Basal Interface of the Martian South Polar Layered Deposits

Using radio waves, we investigated the properties of materials lying below the surface of Mars’ south polar regions (South Polar Layered Deposits; “SPLD”). We made maps of the buried surface below the SPLD (“basal interface”) and measured the radar energy reflected by this interface. From these maps, we measured the SPLD volume as 1.6 million cubic kilometers. Additionally, we found that there are multiple areas throughout the south polar region where the energy reflected from the basal interface is unexpectedly higher than that of the surface. Previous analyses of one such region suggested that these stronger reflections could be caused by the presence of an underground lake.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL093631
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 02:39 pm
The discussion on "super-Earth" was motivated by the latest CHEOPS paper about Nu2 Lupi ... and I think there's broad consensus for retiring the term.

https://arxiv.org/abs/2106.14491

There is similar discomfort with "Earth-like", which usually means "Earth-sized".

--- Tony
The article I posted above to me makes a very persuasive argument for the retirement of the term.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 03:16 pm
Astronomers Thrill at Giant Comet Flying into Our Solar System

Quote
Efforts to study the object since it was announced have been swift. Already a team of astronomers has been able to detect signs of activity, most likely melting ices forming an atmosphere, or “coma,” around its solid nucleus, confirming it to be a comet. “Its brightness has increased a lot, which means that it’s active,” says Rosita Kokotanekova of the European Southern Observatory, who led the observations using a network of telescopes in the Southern Hemisphere. Getting continued rapid observations will be crucial in learning more about the comet. “There might still be a possibility we can see a rotational signal from the nucleus,” Kokotanekova says. “When the activity gets stronger, it will be completely obscured.”
Observing that activity will be enlightening, too, “because we’ve never observed a comet being active so far out [from the sun],” Kokotanekova says. This will allow researchers to probe the regions of the solar system where cometary activity begins. From the object’s initial apparition in DES optics in 2014 to 2018, it did not appear to show activity, meaning it likely “switched on” at some point in the past three years, Fitzsimmons says. “It’s going to give us a really nice ability to study what happens in this transition region—from being a frozen ice ball out in the Oort cloud to a fully active comet in the solar system.”

https://www.scientificamerican.com/article/astronomers-thrill-at-giant-comet-flying-into-our-solar-system/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 03:21 pm
Someone on Twitter has worked out the various launch dates and requirements to reach comet Bernardinelli-Bernstein.

Quote
So, remember that giant "mega comet" I reported on yesterday called 2014 UN271 that's flying into the Solar System?

Well, here are some possible launch dates to send a mission there, after it makes its close approach to Saturn's orbit in 2031!

https://twitter.com/Astro_Jonny/status/1407364662459518980
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2021 03:54 pm
A highly magnetized and rapidly rotating white dwarf as small as the Moon

Abstract
White dwarfs represent the last stage of evolution of stars with mass less than about eight times that of the Sun and, like other stars, are often found in binaries1,2. If the orbital period of the binary is short enough, energy losses from gravitational-wave radiation can shrink the orbit until the two white dwarfs come into contact and merge3. Depending on the component masses, the merger can lead to a supernova of type Ia or result in a massive white dwarf4. In the latter case, the white dwarf remnant is expected to be highly magnetized5,6 because of the strong magnetic dynamo that should arise during the merger, and be rapidly spinning from the conservation of the orbital angular momentum7. Here we report observations of a white dwarf, ZTF J190132.9+145808.7, that exhibits these properties, but to an extreme: a rotation period of 6.94 minutes, a magnetic field ranging between 600 megagauss and 900 megagauss over its surface, and a stellar radius of 2140+160−230
2140

230
+
160
 kilometres, only slightly larger than the radius of the Moon. Such a small radius implies that the star’s mass is close to the maximum white dwarf mass, or Chandrasekhar mass. ZTF J190132.9+145808.7 is likely to be cooling through the Urca processes (neutrino emission from electron capture on sodium) because of the high densities reached in its core.

https://www.nature.com/articles/s41586-021-03615-y
Title: Re: Astronomy & Planetary Science Thread
Post by: edzieba on 06/30/2021 04:16 pm
Someone on Twitter has worked out the various launch dates and requirements to reach comet Bernardinelli-Bernstein.

Quote
So, remember that giant "mega comet" I reported on yesterday called 2014 UN271 that's flying into the Solar System?

Well, here are some possible launch dates to send a mission there, after it makes its close approach to Saturn's orbit in 2031!

https://twitter.com/Astro_Jonny/status/1407364662459518980
With the 2028 C3 not being too far above 100km/s, and Comet Interceptor massing around 850kg, it's tantalisingly close to viable to place a completed Comet Interceptor (launch target 2028) onto an expendable Falcon Heavy, Delta IV Heavy (if still flying then), or Vulcan Centaur 6. It looks like none would be capable as-is, but with the conservative LSP numbers and possibly trading some mass for a kick-stage (and a big trajectory change to take advantage of that) it might juuust be plausible. Vulcan Centaur Heavy - if it's flying by then - may be capable outright.
That's assuming Comet Interceptor is capable of operating 8-9 AU further out than intended (about 1% available solar power for same panel area), though. By the time you start adding extra panels and thermal management while staying inside the same mass budget, that's almost a new probe, and design probably needs to change yesterday to make it happen.
Title: Re: Astronomy & Planetary Science Thread
Post by: Robotbeat on 06/30/2021 04:36 pm
Heck, Atlas V or droneship Falcon 9 may be able to do a 850kg probe to that much with a sufficient kick stage.
Title: Re: Astronomy & Planetary Science Thread
Post by: Zed_Noir on 07/05/2021 05:17 am
Someone on Twitter has worked out the various launch dates and requirements to reach comet Bernardinelli-Bernstein.

Quote
So, remember that giant "mega comet" I reported on yesterday called 2014 UN271 that's flying into the Solar System?

Well, here are some possible launch dates to send a mission there, after it makes its close approach to Saturn's orbit in 2031!

https://twitter.com/Astro_Jonny/status/1407364662459518980 (https://twitter.com/Astro_Jonny/status/1407364662459518980)
With the 2028 C3 not being too far above 100km/s, and Comet Interceptor massing around 850kg, it's tantalisingly close to viable to place a completed Comet Interceptor (launch target 2028) onto an expendable Falcon Heavy, Delta IV Heavy (if still flying then), or Vulcan Centaur 6. It looks like none would be capable as-is, but with the conservative LSP numbers and possibly trading some mass for a kick-stage (and a big trajectory change to take advantage of that) it might juuust be plausible. Vulcan Centaur Heavy - if it's flying by then - may be capable outright.
That's assuming Comet Interceptor is capable of operating 8-9 AU further out than intended (about 1% available solar power for same panel area), though. By the time you start adding extra panels and thermal management while staying inside the same mass budget, that's almost a new probe, and design probably needs to change yesterday to make it happen.


Heck, Atlas V or droneship Falcon 9 may be able to do a 850kg probe to that much with a sufficient kick stage.


By 2028 something a lot more capable than the Falcon Heavy, Delta IV or Vulcan Centaur Heavy should be available. Think the Vulcan Centaur Heavy will not enter service.


If a mission is send what type of sensors is needed on the spacecraft?

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/08/2021 06:54 pm
Observational Evidence for a Thick Disk of Dark Molecular Gas in the Outer Galaxy

Abstract
We present the serendipitous discovery of an extremely broad (ΔVLSR ~ 150 km s−1), faint (Tmb &lt; 10 mK), and ubiquitous 1667 and 1665 MHz ground-state thermal OH emission toward the second quadrant of the outer Galaxy (Rgal &gt; 8 kpc) with the Green Bank Telescope. Originally discovered in 2015, we describe the redundant experimental, observational, and data quality tests of this result over the last five years. The longitude–velocity distribution of the emission unambiguously suggests large-scale Galactic structure. We observe a smooth distribution of OH in radial velocity that is morphologically similar to the H i radial velocity distribution in the outer Galaxy, showing that molecular gas is significantly more extended in the outer Galaxy than previously expected. Our results imply the existence of a thick (−200 pc &lt; z &lt; 200 pc) disk of diffuse (${n}_{{{\rm{H}}}_{2}}$ ~ 5 × 10−3 cm−3) molecular gas in the outer Galaxy previously undetected in all-sky 12CO surveys.

https://iopscience.iop.org/article/10.3847/1538-4357/abf832

Source: https://www.google.co.uk/amp/s/www.koin.com/news/massive-galactic-structure-discovered-by-accident/amp/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/12/2021 07:06 pm
Study Projects a Surge in Coastal Flooding, Starting in 2030s

Quote
In the mid-2030s, every U.S. coast will experience rapidly increasing high-tide floods, when a lunar cycle will amplify rising sea levels caused by climate change.

https://www.nasa.gov/feature/jpl/study-projects-a-surge-in-coastal-flooding-starting-in-2030s
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/13/2021 07:44 am
The problem with this theory isn’t just that it requires active volcanoes on Venus, but explosive active ones at a high level in the recent past to get the phosphides in the amounts where they need to be in the atmosphere.


Biosignature Spotted on Venus Could Be From Volcanoes, Not Life

Quote
“The phosphine is not telling us about the biology of Venus,” said Jonathan Lunine, a planetary scientist at Cornell University and co-author of the paper, in a university press release. “It’s telling us about the geology. Science is pointing to a planet that has active explosive volcanism today or in the very recent past.”

But the mystery of whether Venus has phosphine or not, and what might have produced it, is far from settled. “I sadly remain unconvinced by this latest argument,” said Clara Sousa-Silva, a quantum astrochemist at the Center for Astrophysics | Harvard and Smithsonian, in an email. “The reaction of mineral phosphides with concentrated sulfuric acid will not necessarily generate phosphine. ... A likely outcome of reacting phosphides with concentrated sulfuric acid would be an oxidation reaction and not production of phosphine.”

Sousa-Silva’s previous work has examined the atmospheres of Venus and other planets for potential signs of life like phosphine. She added, “we have known (and stated as much, repeatedly) that there are abiotic routes for the formation of phosphine, including volcanism. It’s just that these routes are extremely rare and inefficient.”

https://gizmodo.com/biosignature-spotted-on-venus-could-be-from-volcanoes-1847275328
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/13/2021 03:19 pm
TESS Finds Related Stars Have Young Exoplanets:

https://youtu.be/RE-NpbAW3lM
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/13/2021 07:08 pm
A Single-Year Cosmic Ray Event at 5410 BCE Registered in 14C of Tree Rings

Plain Language Summary
The 14C data of tree rings register extreme storms of solar energetic particles (SEPs), far larger than the largest SEP event ever observed in the Space Era. So far, three extreme SEP events have been reported as a rapid 14C increase in tree rings and 10Be and 36Cl increases in ice cores. In this study, we found a new rapid 14C increase in 5410 BCE using annual 14C content in ring samples from California, Switzerland, and Finland. The 14C signature of 5410 BCE event ties the origin of this 14C excursion to an extreme SEP event similar to three other extreme SEP events (774/775 CE, 992/993 CE, and ∼660 BCE) confirmed with radionuclides of ice cores.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL093419

Source: https://phys.org/news/2021-07-tree-newly-extreme-solar-event.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/14/2021 03:35 pm
A hot subdwarf–white dwarf super-Chandrasekhar candidate supernova Ia progenitor

Abstract
Supernovae Ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the Universe. They are understood to result from a thermonuclear detonation in a white dwarf that formed from the exhausted core of a star more massive than the Sun. However, the possible progenitor channels leading to an explosion are a long-standing debate, limiting the precision and accuracy of supernovae Ia as distance indicators. Here we present HD 265435, a binary system with an orbital period of less than a hundred minutes that consists of a white dwarf and a hot subdwarf, which is a stripped core-helium-burning star. The total mass of the system is 1.65 ± 0.25 solar masses, exceeding the Chandrasekhar limit (the maximum mass of a stable white dwarf). The system will merge owing to gravitational wave emission in 70 million years, likely triggering a supernova Ia event. We use this detection to place constraints on the contribution of hot subdwarf–white dwarf binaries to supernova Ia progenitors.

https://www.nature.com/articles/s41550-021-01413-0

Source: http://www.sci-news.com/astronomy/hd-265435-type-ia-supernova-progenitor-09857.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/18/2021 10:12 am
Methane in the plumes of Saturn's moon Enceladus: Possible signs of life?

Quote
An unknown methane-producing process is likely at work in the hidden ocean beneath the icy shell of Saturn's moon Enceladus, suggests a new study published in Nature Astronomy by scientists at the University of Arizona and Paris Sciences & Lettres University.

https://www.google.co.uk/amp/s/phys.org/news/2021-07-methane-plumes-saturn-moon-enceladus.amp

Related paper:

Bayesian analysis of Enceladus’s plume data to assess methanogenesis

Abstract
Observations from NASA’s Cassini spacecraft established that Saturn’s moon Enceladus has an internal liquid ocean. Analysis of a plume of ocean material ejected into space suggests that alkaline hydrothermal vents are present on Enceladus’s seafloor. On Earth, such deep-sea vents harbour microbial ecosystems rich in methanogenic archaea. Here we use a Bayesian statistical approach to quantify the probability that methanogenesis (biotic methane production) might explain the escape rates of molecular hydrogen and methane in Enceladus’s plume, as measured by Cassini instruments. We find that the observed escape rates (1) cannot be explained solely by the abiotic alteration of the rocky core by serpentinization; (2) are compatible with the hypothesis of habitable conditions for methanogens; and (3) score the highest likelihood under the hypothesis of methanogenesis, assuming that the probability of life emerging is high enough. If the probability of life emerging on Enceladus is low, the Cassini measurements are consistent with habitable yet uninhabited hydrothermal vents and point to unknown sources of methane (for example, primordial methane) awaiting discovery by future missions.

https://www.nature.com/articles/s41550-021-01372-6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/21/2021 08:32 am
EHT Pinpoints Dark Heart of the Nearest Radio Galaxy

Quote
In a new paper published Monday in Nature Astronomy, data from the 2017 Event Horizon Telescope (EHT) observations have been analyzed to image Centaurus A in unprecedented detail.

"This allows us for the first time to see and study an extragalactic radio jet on scales smaller than the distance light travels in one day. We see up close and personal how a monstrously gigantic jet launched by a supermassive black hole is being born,” says astronomer Michael Janssen of the Max Planck Institute for Radio Astronomy and Radboud University.

Quote
The researchers predict that future observations at an even shorter wavelength and higher resolution will be able to photograph the central black hole of Centaurus A. This will require the use of space-based satellite observatories.

“These data are from the same observing campaign that delivered the famous image of the black hole in M87. The new results show that the EHT provides a treasure trove of data on the rich variety of black holes and there is still more to come”, says Heino Falcke, EHT board member and professor for astrophysics at Radboud University.

https://www.newswise.com/articles/eht-pinpoints-dark-heart-of-the-nearest-radio-galaxy

Event Horizon Telescope observations of the jet launching and collimation in Centaurus A

Abstract
Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii (rg ≡ GM/c2) scales in nearby sources1. Centaurus A is the closest radio-loud source to Earth2. It bridges the gap in mass and accretion rate between the supermassive black holes (SMBHs) in Messier 87 and our Galactic Centre. A large southern declination of −43° has, however, prevented VLBI imaging of Centaurus A below a wavelength of 1 cm thus far. Here we show the millimetre VLBI image of the source, which we obtained with the Event Horizon Telescope at 228 GHz. Compared with previous observations3, we image the jet of Centaurus A at a tenfold higher frequency and sixteen times sharper resolution and thereby probe sub-lightday structures. We reveal a highly collimated, asymmetrically edge-brightened jet as well as the fainter counterjet. We find that the source structure of Centaurus A resembles the jet in Messier 87 on ~500 rg scales remarkably well. Furthermore, we identify the location of Centaurus A’s SMBH with respect to its resolved jet core at a wavelength of 1.3 mm and conclude that the source’s event horizon shadow4 should be visible at terahertz frequencies. This location further supports the universal scale invariance of black holes over a wide range of masses5,6.

https://www.nature.com/articles/s41550-021-01417-w
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/21/2021 03:36 pm
Chunk of an ancient supercontinent discovered under New Zealand

Quote
As the California heat blazed outside in the summer of 2018, Rose Turnbull sat in the cool confines of a windowless basement sorting through grains of fine sand. A geologist based in New Zealand, Turnbull was in a colleague’s lab at California State University, Northridge, trying to find tiny crystals of zircon, which she hoped would help unravel secrets of the mysterious eighth continent of Zealandia, also known by its Māori name Te Riu-a-Māui.

The task required a practiced hand and a bit of elbow grease—or rather, nose grease. Turnbull demonstrates over Zoom, raising the closed tweezers to the outside of her nose to pick up a bit of oil, which prevents the grains from zinging across the room when plucked.

The crystals hailed from rocks that were collected from the islands of New Zealand, which are among the few bits of Zealandia's nearly two million square miles that poke above the sea. Only recently recognized by scientists, Zealandia is the most submerged, thinnest, and youngest continent yet found. Turnbull, who works at the research and consulting group GNS Science in New Zealand, and her colleagues wanted to know more about the processes that shaped this unusual landmass.

https://www.nationalgeographic.com/science/article/chunk-of-an-ancient-supercontinent-discovered-under-new-zealand

A hidden Rodinian lithospheric keel beneath Zealandia, Earth’s newly recognized continent

We present a data set of >1500 in situ O-Hf-U-Pb zircon isotope analyses that document the existence of a concealed Rodinian lithospheric keel beneath continental Zealandia. The new data reveal the presence of a distinct isotopic domain of Paleozoic–Mesozoic plutonic rocks that contain zircon characterized by anomalously low δ18O values (median = +4.1‰) and radiogenic εHf(t) (median = +6.1). The scale (>10,000 km2) and time span (>>250 m.y.) over which plutonic rocks with this anomalously low-δ18O signature were emplaced appear unique in a global context, especially for magmas generated and emplaced along a continental margin. Calculated crustal-residence ages (depleted mantle model, TDM) for this low-δ18O isotope domain range from 1300 to 500 Ma and are interpreted to represent melting of a Precambrian lithospheric keel that was formed and subsequently hydrothermally altered during Rodinian assembly and rifting. Recognition of a concealed Precambrian lithosphere beneath Zealandia and the uniqueness of the pervasive low-δ18O isotope domain link Zealandia to South China, providing a novel test of specific hypotheses of continental block arrangements within Rodinia.

https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G48711.1/598229/A-hidden-Rodinian-lithospheric-keel-beneath
Title: Re: Astronomy & Planetary Science Thread
Post by: ugordan on 07/22/2021 06:30 pm
Astronomers make first clear detection of a moon-forming disc around an exoplanet

Quote
Our work presents a clear detection of a disc in which satellites could be forming,” says Myriam Benisty, a researcher at the University of Grenoble, France, and at the University of Chile, who led the new research published today in The Astrophysical Journal Letters. “Our ALMA observations were obtained at such exquisite resolution that we could clearly identify that the disc is associated with the planet and we are able to constrain its size for the first time,” she adds.

The disc in question, called a circumplanetary disc, surrounds the exoplanet PDS 70c, one of two giant, Jupiter-like planets orbiting a star nearly 400 light-years away. Astronomers had found hints of a “moon-forming” disc around this exoplanet before but, since they could not clearly tell the disc apart from its surrounding environment, they could not confirm its detection — until now.

https://www.eso.org/public/news/eso2111/
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 07/22/2021 10:51 pm
Impressive they essentially discovered an alien equivalent of the Galilean moons' nursery.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/27/2021 08:50 am
A peculiarly short-duration gamma-ray burst from massive star core collapse

Abstract
Gamma-ray bursts (GRBs) have been phenomenologically classified into long and short populations based on the observed bimodal distribution of duration1. Multi-wavelength and multi-messenger observations in recent years have revealed that in general long GRBs originate from massive star core collapse events2, whereas short GRBs originate from binary neutron star mergers3. It has been known that the duration criterion is sometimes unreliable, and multi-wavelength criteria are needed to identify the physical origin of a particular GRB4. Some apparently long GRBs have been suggested to have a neutron star merger origin5, whereas some apparently short GRBs have been attributed to genuinely long GRBs6 whose short, bright emission is slightly above the detector’s sensitivity threshold. Here, we report the comprehensive analysis of the multi-wavelength data of the short, bright GRB 200826A. Characterized by a sharp pulse, this burst shows a duration of 1 second and no evidence of an underlying longer-duration event. Its other observational properties such as its spectral behaviours, total energy and host galaxy offset are, however, inconsistent with those of other short GRBs believed to originate from binary neutron star mergers. Rather, these properties resemble those of long GRBs. This burst confirms the existence of short-duration GRBs with stellar core-collapse origin4, and presents some challenges to the existing models.

https://www.nature.com/articles/s41550-021-01395-z

Discovery and confirmation of the shortest gamma-ray burst from a collapsar

Abstract
Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the Universe. The duration and hardness distribution of GRBs has two clusters1, now understood to reflect (at least) two different progenitors2. Short-hard GRBs (SGRBs; T90 &lt; 2 s) arise from compact binary mergers, and long-soft GRBs (LGRBs; T90 &gt; 2 s) have been attributed to the collapse of peculiar massive stars (collapsars)3. The discovery of SN 1998bw/GRB 980425 (ref. 4) marked the first association of an LGRB with a collapsar, and AT 2017gfo (ref. 5)/GRB 170817A/GW170817 (ref. 6) marked the first association of an SGRB with a binary neutron star merger, which also produced a gravitational wave. Here, we present the discovery of ZTF20abwysqy (AT2020scz), a fast-fading optical transient in the Fermi satellite and the Interplanetary Network localization regions of GRB 200826A; X-ray and radio emission further confirm that this is the afterglow. Follow-up imaging (at rest-frame 16.5 days) reveals excess emission above the afterglow that cannot be explained as an underlying kilonova, but which is consistent with being the supernova. Although the GRB duration is short (rest-frame T90 of 0.65 s), our panchromatic follow-up data confirm a collapsar origin. GRB 200826A is the shortest LGRB found with an associated collapsar; it appears to sit on the brink between a successful and a failed collapsar. Our discovery is consistent with the hypothesis that most collapsars fail to produce ultra-relativistic jets.

https://www.nature.com/articles/s41550-021-01428-7

Source: https://www.google.co.uk/amp/s/scitechdaily.com/nasas-fermi-spots-a-weird-pulse-of-high-energy-radiation-racing-toward-earth/amp/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/27/2021 09:34 am
Meteor wows Norway after blazing through night sky https://www.bbc.co.uk/news/world-europe-57962384
Title: Re: Astronomy & Planetary Science Thread
Post by: Rondaz on 08/04/2021 09:22 pm
TESS Maps Red Giants Across the Sky

https://youtu.be/uZaRnyN0wp0
Title: Re: Astronomy & Planetary Science Thread
Post by: Rondaz on 08/04/2021 09:26 pm
TESS Tracks a Giant’s Pulsations

https://youtu.be/jrI-7COKnic
Title: Re: Astronomy & Planetary Science Thread
Post by: Rondaz on 08/04/2021 09:27 pm
Tuning Into a Trio of Red Giants

https://youtu.be/MRXC12BFStI
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/05/2021 03:22 pm
A neighbouring Planetary system reveals its secrets (ESO cast 242 Light):

https://youtu.be/BfnlIoapky0

Quote
A team of astronomers have used ESO’s Very Large Telescope in Chile to shed new light on planets around a nearby star that resemble those in the inner Solar System. This video summarises what they found about the planetary system, called L 98-59.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/06/2021 04:41 pm
One Year in the Life of Young Suns: Data Constrained Corona-Wind Model of kappa1 Ceti

The young magnetically active solar-like stars are efficient generators of ionizing radiation in the form of X-ray and Extreme UV (EUV) flux, stellar wind and eruptive events. These outputs are the critical factors affecting atmospheric escape and chemistry of (exo)planets around active stars. While X-ray fluxes and surface magnetic fields can be derived from observations, the EUV emission and wind mass fluxes, Coronal Mass Ejections and associated Stellar Energetic Particle events cannot be directly observed. Here, we present the results of a three-dimensional magnetohydrodynamic (MHD) model with inputs constrained by spectropolarimetric data, HST/STIS Far UV, X-ray data data and stellar magnetic maps reconstructed at two epochs separated by 11 months. The simulations show that over the course of the year, the global stellar corona had undergone a drastic transition from a simple dipole-like to a tilted dipole with multipole field components, and thus, provided favorable conditions for Corotating Interaction Events (CIRs) that drive strong shocks. The dynamic pressure exerted by CIRs are 1300 times larger than those observed from the Sun and can contribute to the atmospheric erosion of early Venus, Earth, Mars and young Earth-like exoplanets. Our data-constrained MHD model provides the framework to model coronal environments of G-M planet hosting dwarfs. The model outputs can serve as a realistic input for exoplanetary atmospheric models to evaluate the impact of stellar coronal emission, stellar winds and CIRs on their atmospheric escape and chemistry that can be tested in the upcoming JWST and ground-based observations.

https://arxiv.org/abs/2106.01284
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/10/2021 02:19 pm
Quote
About 66 million years ago, an estimated 6-mile-wide (9.6 kilometers) object slammed into Earth, triggering a cataclysmic series of events that resulted in the demise of non-avian dinosaurs.

Now, scientists think they know where that object came from.

According to new research, the impact was caused by a giant dark primitive asteroid from the outer reaches of the solar system's main asteroid belt, situated between Mars and Jupiter. This region is home to many dark asteroids — space rocks with a chemical makeup that makes them appear darker (reflecting very little light) compared with other types of asteroids.

Quote
Simulating over hundreds of millions of years, the model showed thermal forces and gravitational tugs from planets periodically slingshotting large asteroids out of the belt. On average, an asteroid more than 6 miles wide from the outer edge of the belt was flung into a collision course with Earth once every 250 million years, the researchers found. This calculation makes such an event five times more common than previously thought and consistent with the Chicxulub crater created just 66 million years ago, which is the only known impact crater thought to have been produced by such a large asteroid in the last 250 million years. Furthermore, the model looked at the distribution of "dark" and "light" impactors in the asteroid belt and showed half of the expelled asteroids were the dark carbonaceous chondrites, which matches the type thought to have caused Chicxulub crater.

https://www.livescience.com/dinosaur-killing-asteroid-origin-dark.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/10/2021 04:03 pm
Quote
The recurrent nova RS Ophiuchi (RS Oph), located in the constellation of Ophiuchus, is in a rare outburst, its first for more than 15 years. RS Oph brightened rapidly on 8 August 2021 from around magnitude +12 to shine presently at about magnitude +4.8, a 600-fold in just a day. This is its first outburst since February 2006 and only five other eruptions have been observed since 1898.

https://astronomynow.com/2021/08/10/rs-ophiuchi-in-a-rare-outburst-to-naked-eye-visibility/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/10/2021 04:11 pm
An international team of astronomers using data from NASA’s Juno spacecraft, the W.M. Keck Observatory and Japan’s Hisaki satellite was able to nail down the source of Jupiter’s surprising temperature, reporting their findings in the journal Nature.

“We found that Jupiter’s intense aurora, the most powerful in the solar system, is responsible for heating the entire planet’s upper atmosphere to surprisingly high temperatures,” said James O’Donoghue of the JAXA Institute of Space and Astronautical Science in Sagamihara, Japan.

https://youtu.be/pXTpL3DA6yY

https://astronomynow.com/2021/08/04/jupiters-high-temperature-traced-to-planets-powerful-auroras/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/16/2021 03:15 pm
Rings around a black hole from X-ray echoes off interstellar dust

Quote
Some 7,800 light years from Earth, a black hole is actively sucking in material from a companion star with about half the mass of the Sun. The material forms a disc around the black hole, glowing in X-rays as particles crash together in a swirling inferno. The binary system is known as V404 Cygni and on 5 June 2015, the Swift space telescope detected an X-ray outburst that created a spectacular ring of “light echoes” as the high-energy radiation bounced off intervening clouds of smoke-like interstellar dust. In the composite image below, observations by the Chandra X-ray Telescope (shown in blue) were combined with optical imagery from the Pan-STARRS telescope in Hawaii. Eight concentric X-ray echoes can be seen as radiation reflects off dust at different distances.

https://astronomynow.com/2021/08/08/rings-around-a-black-hole-from-x-ray-echoes-off-interstellar-dust/
Title: Re: Astronomy & Planetary Science Thread
Post by: matthewkantar on 08/16/2021 03:46 pm
Rings around a black hole from X-ray echoes off interstellar dust

Quote
Some 7,800 light years from Earth, a black hole is actively sucking in material from a companion star with about half the mass of the Sun. The material forms a disc around the black hole, glowing in X-rays as particles crash together in a swirling inferno. The binary system is known as V404 Cygni and on 5 June 2015, the Swift space telescope detected an X-ray outburst that created a spectacular ring of “light echoes” as the high-energy radiation bounced off intervening clouds of smoke-like interstellar dust. In the composite image below, observations by the Chandra X-ray Telescope (shown in blue) were combined with optical imagery from the Pan-STARRS telescope in Hawaii. Eight concentric X-ray echoes can be seen as radiation reflects off dust at different distances.

https://astronomynow.com/2021/08/08/rings-around-a-black-hole-from-x-ray-echoes-off-interstellar-dust/

Am stunned that events 7,800 LYs away are a danger to detectors on or near Earth. Wild!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/17/2021 10:18 am
Saturn’s core is a big, diffuse, rocky slushball

Quote
The process should leave planets like Jupiter and Saturn with a solid, rocky core buried deep within the envelope of gas. But confirming that core composition has been difficult. Now, researchers have used features in Saturn's rings to detect subtle gravitational influences from the core. While not definitive, the results suggest that the core is large, and the solid, rocky portion is widely spread out across that area.

Quote
The new work relies on the features of the waves we've detected within Saturn's rings. In essence, the researchers built multiple models of what Saturn's core could look like and check whether the models would create the patterns we actually see. The real-world data is then used to put constraints on the possible elements of Saturn's core.

Quote
Overall, the models that fit the data place Saturn's core-envelope boundary a significant distance from the planet's center, roughly 60 percent of the way to the surface. That's a radius of nearly 60,000 kilometers, or over nine times Earth's radius.
The exact composition of the core is much harder to figure out, since the constraints are fairly wide. The total mass of heavier elements in the core is about 19 times Earth's mass, consistent with models of gas-giant formation that place rock and iron at the center, although a lot of this material could also be water ice. Yet the total mass of the core could be as high as 55 times the Earth's mass, indicating that there's a lot of other material there—likely metallic hydrogen and helium.

https://arstechnica.com/science/2021/08/saturns-core-is-a-big-diffuse-rocky-slushball/

A diffuse core in Saturn revealed by ring seismology

Abstract
The best constraints on the internal structures of giant planets have historically originated from measurements of their gravity fields1,2,3. These data are inherently mostly sensitive to a planet’s outer regions, stymieing efforts to measure the mass and compactness of the cores of Jupiter2,4,5 and Saturn6,7. However, studies of Saturn’s rings have detected waves driven by pulsation modes within the planet8,9,10,11, offering independent seismic probes of Saturn’s interior12,13,14. The observations reveal gravity-mode pulsations, which indicate that part of Saturn’s deep interior is stable against convection13. Here, we compare structural models with gravity and seismic measurements from Cassini to show that the data can only be explained by a diffuse, stably stratified core–envelope transition region in Saturn extending to approximately 60% of the planet’s radius and containing approximately 17 Earth masses of ice and rock. This gradual distribution of heavy elements constrains mixing processes at work in Saturn, and it may reflect the planet’s primordial structure and accretion history.

https://www.nature.com/articles/s41550-021-01448-3
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/19/2021 07:20 pm
Cool Worlds - Could Origami Be The Key to Detecting Exomoons?

https://youtu.be/2sXTNfU5pHc

Transit Origami: A Method to Coherently Fold Exomoon Transits in Time Series Photometry

One of the simplest ways to identify an exoplanetary transit is to phase fold a photometric time series upon a trial period - leading to a coherent stack when using the correct value. Such phase-folded transits have become a standard data visualisation in modern transit discovery papers. There is no analogous folding mechanism for exomoons, which would have to represent some kind of double-fold; once for the planet and then another for the moon. Folding with the planet term only, a moon imparts a small decrease in the surrounding out-of-transit averaged intensity, but its incoherent nature makes it far less convincing than the crisp stacks familiar to exoplanet hunters. Here, a new approach is introduced that can be used to achieve the transit origami needed to double fold an exomoon, in the case where a planet exhibits TTVs. This double fold has just one unknown parameter, the satellite-to-planet mass ratio, and thus a simple one-dimensional grid search can be used to rapidly identify power associated with candidate exomoons. The technique is demonstrated on simulated light curves, exploring the breakdown limits of close-in and/or inclined satellites. As an example, the method is deployed on Kepler-973b, a warm mini-Neptune exhibiting an 8 minute TTV, where the possibility that the TTVs are caused by a single exomoon is broadly excluded, with upper limits probing down to a Ganymede-sized moon.

https://arxiv.org/abs/2108.02903
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/26/2021 09:56 am
Interstellar objects outnumber Solar system objects in the Oort cloud

ABSTRACT
Here, we show that the detection of Borisov implies that interstellar objects outnumber Solar system objects in the Oort cloud, whereas the reverse is true near the Sun due to the stronger gravitational focusing of bound objects. This hypothesis can be tested with stellar occultation surveys of the Oort cloud. Furthermore, we demonstrate that ∼1 per cent
 of carbon and oxygen in the Milky Way Galaxy may be locked in interstellar objects, implying a heavy element budget for interstellar objects comparable to the heavy element budget of the minimum mass Solar nebula model. There is still considerable uncertainty regarding the size distribution of the interstellar objects.

https://academic.oup.com/mnrasl/article-abstract/507/1/L16/6353622?redirectedFrom=fulltext
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/26/2021 10:03 am
Belatedly Habitable Planets

Abstract
Stars do not remain static, so their habitable zones evolve in time. Over a star's evolution, its habitable zone encompasses new planets, and it remains uncertain whether these planets can become habitable. We refer to this often overlooked class of planets as lying in the belatedly habitable zone, and stress that many planets found in the habitable zones of other stars will belong to this class. Future studies should take belated habitability into account and not implicitly assume that these planets are habitable.

https://iopscience.iop.org/article/10.3847/2515-5172/ac1ea2
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/26/2021 10:13 am
“Anomalous Stellar Acceleration: Causes and Consequences,” JBIS Vol. 74 (2021), pp. 269-275

Abstract:

As a successor to Hipparcus, an earlier European Space Agency (ESA) space telescope, the ESA Gaia space telescope was launched in December 2013 and is currently on-station at the Earth-Sun L2 Lagrange point, about 1.5 x 106km from Earth. The goal of this mission is accurate determination of position and motions for ~1 billion stars in the Milky Way galaxy [1].

https://bis-space.com/shop/product/anomalous-stellar-acceleration-causes-and-consequences/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/27/2021 11:13 am
Fastest-moving asteroid flies closer to Sun than Mercury

Quote
Astronomers using the 570-megapixel Dark Energy Camera have found the fastest-moving asteroid yet discovered, a 1-kilometre-wide (0.6-mile-wide) body that crosses the orbits of Venus and Mercury and passes within just 20 million kilometres (12 million miles) of the Sun every 113 days. The asteroid, catalogued as 2021 PH27, heats up to almost 500 Celsius (about 900 Fahrenheit) during close approach, hot enough to melt lead.

Quote
The asteroid, catalogued as 2021 PH27, may have originated in the main asteroid belt between Mars and Jupiter, subsequently dislodged by gravitational interactions with the inner planets. But its orbit is tilted 32 degrees to the Sun’s equatorial plane, indicating it could be an extinct comet that ended up in a short-period orbit after passing by a terrestrial planet.

https://astronomynow.com/2021/08/23/fastest-moving-asteroid-flies-closer-to-sun-than-mercury/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/27/2021 11:22 am
New class of habitable exoplanets are 'a big step forward' in the search for life

Quote
A new class of exoplanet very different to our own, but which could support life, has been identified by astronomers, which could greatly accelerate the search for life outside our Solar System.

Quote
The researchers have identified a new class of habitable planets, dubbed ‘Hycean’ planets – ocean-covered planets with hydrogen-rich atmospheres – which are more numerous and observable than Earth-like planets.

The researchers say the results, reported in The Astrophysical Journal, could mean that finding biosignatures of life outside our Solar System within the next few years is a real possibility.

“Hycean planets open a whole new avenue in our search for life elsewhere,” said Dr Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.

Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth’s most extreme aquatic environments.

https://www.cam.ac.uk/research/news/new-class-of-habitable-exoplanets-are-a-big-step-forward-in-the-search-for-life

Habitability and Biosignatures of Hycean Worlds

We investigate a new class of habitable planets composed of water-rich interiors with massive oceans underlying H2-rich atmospheres, referred to here as Hycean worlds. With densities between those of rocky super-Earths and more extended mini-Neptunes, Hycean planets can be optimal candidates in the search for exoplanetary habitability and may be abundant in the exoplanet population. We investigate the bulk properties (masses, radii, and temperatures), potential for habitability, and observable biosignatures of Hycean planets. We show that Hycean planets can be significantly larger compared to previous considerations for habitable planets, with radii as large as 2.6 Earth radii (2.3 Earth radii) for a mass of 10 Earth masses (5 Earth masses). We construct the Hycean habitable zone (HZ), considering stellar hosts from late M to sun-like stars, and find it to be significantly wider than the terrestrial-like HZ. While the inner boundary of the Hycean HZ corresponds to equilibrium temperatures as high as ~500 K for late M dwarfs, the outer boundary is unrestricted to arbitrarily large orbital separations. Our investigations include tidally locked `Dark Hycean' worlds that permit habitable conditions only on their permanent nightsides and `Cold Hycean' worlds that see negligible irradiation. Finally, we investigate the observability of possible biosignatures in Hycean atmospheres. We find that a number of trace terrestrial biomarkers which may be expected to be present in Hycean atmospheres would be readily detectable using modest observing time with the James Webb Space Telescope (JWST). We identify a sizable sample of nearby potential Hycean planets that can be ideal targets for such observations in search of exoplanetary biosignatures.

https://arxiv.org/abs/2108.10888
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/01/2021 03:46 pm
A quarter of Sun-like stars eat their own planets, according to new research

Quote
The relatively calm history of our Solar System has favoured the flourishing of life here on Earth. In the search for alien worlds that may contain life, we can narrow down the targets if we have a way to identify systems that have had similarly peaceful pasts.

Our international team of astronomers has tackled this issue in research published in Nature Astronomy. We found that between 20% and 35% of Sun-like stars eat their own planets, with the most likely figure being 27%.

https://theconversation.com/a-quarter-of-sun-like-stars-eat-their-own-planets-according-to-new-research-166904

Here’s the related paper:

Chemical evidence for planetary ingestion in a quarter of Sun-like stars

Abstract
Stellar members of binary systems are formed from the same material, and therefore they should be chemically identical. However, recent studies have unveiled chemical differences between the two members of binary pairs composed of Sun-like stars. These chemically inhomogeneous binaries represent one of the most contradictory examples in stellar astrophysics and a source of tension between theory and observations. It is still unclear whether the abundance variations are the result of inhomogeneities in the protostellar gas clouds or are due to planet engulfment events that occurred after the stellar formation. The former scenario undermines the general belief that the chemical makeup of stars provides the fossil information of the environment in which they formed, whereas the second scenario would shed light on the possible evolutionary paths of planetary systems. Our study provides compelling evidence in favour of the planet engulfment scenario. We also establish that planet engulfment events occur in Sun-like stars with a 20–35% probability. Therefore, an important fraction of planetary systems undergo very dynamical evolutionary paths that critically modify their architectures, unlike our calm Solar System. This study opens the possibility of using chemical abundances of stars to identify which ones are the most likely to host Solar System analogues.

https://www.nature.com/articles/s41550-021-01451-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/02/2021 08:36 pm
Radio evidence of a stellar merger

Core collapse supernovae occur when a massive star exhausts its fuel and explodes. Theorists have predicted that a similar explosion could occur if an evolved massive star merges with a compact companion, such as a neutron star. Dong et al. have identified a radio source that was not present in earlier radio surveys. Follow-up radio and optical spectroscopy show that it is an expanding supernova remnant slamming into surrounding material, probably ejected from the star centuries before it exploded. An unidentified x-ray transient occurred at a consistent location in 2014, suggesting an explosion at that time that produced a jet. The authors suggest that the most likely explanation is a merger-triggered supernova. —KTS

https://www.science.org/doi/10.1126/science.abg6037

Source: https://www.eurekalert.org/news-releases/927166
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/08/2021 02:35 pm
The Enigmatic Brown Dwarf WISEA J153429.75-104303.3 (a.k.a. "The Accident")

Abstract
Continued follow-up of WISEA J153429.75−104303.3, announced in Meisner et al., has proven it to have an unusual set of properties. New imaging data from Keck/MOSFIRE and HST/WFC3 shows that this object is one of the few faint proper motion sources known with J − ch2 &gt;8 mag, indicating a very cold temperature consistent with the latest known Y dwarfs. Despite this, it has W1−W2 and ch1−ch2 colors ∼1.6 mag bluer than a typical Y dwarf. A new trigonometric parallax measurement from a combination of WISE, Spitzer, and HST astrometry confirms a nearby distance of ${16.3}_{-1.2}^{+1.4}$ pc and a large transverse velocity of 207.4 ± 15.9 km s−1. The absolute J, W2, and ch2 magnitudes are in line with the coldest known Y dwarfs, despite the highly discrepant W1−W2 and ch1−ch2 colors. We explore possible reasons for the unique traits of this object and conclude that it is most likely an old, metal-poor brown dwarf and possibly the first Y subdwarf. Given that the object has an HST F110W magnitude of 24.7 mag, broadband spectroscopy and photometry from JWST are the best options for testing this hypothesis.

https://iopscience.iop.org/article/10.3847/2041-8213/ac0437
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/09/2021 09:37 pm
ESO captures best images yet of peculiar “dog-bone” asteroid

Quote
Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT), a team of astronomers have obtained the sharpest and most detailed images yet of the asteroid Kleopatra. The observations have allowed the team to constrain the 3D shape and mass of this peculiar asteroid, which resembles a dog bone, to a higher accuracy than ever before. Their research provides clues as to how this asteroid and the two moons that orbit it formed.

https://www.eso.org/public/news/eso2113/?lang

Accompanying video:

https://youtu.be/3TUjPyDeZec
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/10/2021 09:32 am
A search of the full six years of the Dark Energy Survey for outer Solar System objects

We present the results of a search for outer Solar System objects in the full six years of data (Y6) from the Dark Energy Survey (DES). The DES covered a contiguous 5000 deg2 of the southern sky with ≈80,000 3 deg2 exposures in the grizY optical/IR filters between 2013 and 2019. This search yielded 815 trans-Neptunian objects (TNOs), one Centaur and one Oort cloud comet, with 461 objects reported for the first time in this paper. We present methodology that builds upon our previous search carried out on the first four years of data. Here, all DES images were reprocessed with an improved detection pipeline that leads to an average completeness gain of 0.47 mag per exposure, as well as an improved transient catalog production and optimized algorithms for linkage of detections into orbits. All objects were verified by visual inspection and by computing the sub-threshold significance, the total signal-to-noise ratio in the stack of images in which the object's presence is indicated by the orbit fit, but no detection was reported. This yields a highly pure catalog of TNOs complete to r≈23.8 mag and distances 29&lt;d&lt;2500 au. The Y6 TNOs have minimum (median) of 7 (12) distinct nights' detections and arcs of 1.1 (4.2) years, and will have grizY magnitudes available in a further publication. We present software for simulating our observational biases that enable comparisons of population models to our detections. Initial inferences demonstrating the statistical power of the DES catalog are: the data are inconsistent with the CFEPS-L7 model for the classical Kuiper Belt; the 16 ``extreme'' TNOs (a&gt;150 au, q&gt;30 au) are consistent with the null hypothesis of azimuthal isotropy; and non-resonant TNOs with q&gt;38 au, a&gt;50 au show a highly significant tendency to be sunward of the major mean motion resonances, whereas this tendency is not present for q&lt;38 au.

https://arxiv.org/abs/2109.03758

Source: https://www.sciencealert.com/over-450-new-objects-have-been-found-in-the-cold-dark-reaches-of-the-solar-system
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/13/2021 08:15 pm
Quote
Physicists at the University of Sussex have discovered that black holes exert a pressure on their environment, in a scientific first.

In 1974 Stephen Hawking made the seminal discovery that black holes emit thermal radiation. Previous to that, black holes were believed to be inert, the final stages of a dying heavy star.

The University of Sussex scientists have shown that they are in fact even more complex thermodynamic systems, with not only a temperature but also a pressure.

https://www.sussex.ac.uk/news/research?id=56072

Quantum gravitational corrections to the entropy of a Schwarzschild black hole

ABSTRACT
We calculate quantum gravitational corrections to the entropy of black holes using the Wald entropy formula within an effective field theory approach to quantum gravity. The corrections to the entropy are calculated to second order in curvature and we calculate a subset of those at third order. We show that, at third order in curvature, interesting issues appear that had not been considered previously in the literature. The fact that the Schwarzschild metric receives corrections at this order in the curvature expansion has important implications for the entropy calculation. Indeed, the horizon radius and the temperature receive corrections. These corrections need to be carefully considered when calculating the Wald entropy.

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.066012?ft=1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/17/2021 09:24 am
Quote
Did Jupiter just get smacked again? Amateur astronomer José Luis Pereira of Brazil just discovered a probable new impact at the gas giant on September 13th at around 22:39:30 UT (18:39:30 EDT). Weather conditions were poor at the time, but Pereira decided to search anyway for possible flashes with DeTeCt software. The free program, created by planetary observer Marc Delcroix, is a useful tool to check for transient events such as planetary impacts.

https://skyandtelescope.org/astronomy-news/amateur-spots-possible-new-impact-flash-at-jupiter/
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/21/2021 02:14 pm
Quote
Water is essential for life on Earth and other planets, and scientists have found ample evidence of water in Mars’ early history. But Mars has no liquid water on its surface today. New research from Washington University in St. Louis suggests a fundamental reason: Mars may be just too small to hold onto large amounts of water.
Wang and his team measured the potassium isotope compositions of 20 previously confirmed Martian meteorites, selected to be representative of the bulk silicate composition of the red planet.

Quote
Using this approach, the researchers determined that Mars lost more potassium and other volatiles than Earth during its formation, but retained more of these volatiles than the moon and asteroid 4-Vesta, two much smaller and drier bodies than Earth and Mars.

Quote
The researchers found a well-defined correlation between body size and potassium isotopic composition.
"This study emphasizes that there is a very limited size range for planets to have just enough but not too much water to develop a habitable surface environment," said Klaus Mezger of the Center for Space and Habitability at the University of Bern, Switzerland, a co-author of the study. "These results will guide astronomers in their search for habitable exoplanets in other solar systems."

Quote
Wang now thinks that, for planets that are within habitable zones, planetary size probably should be more emphasized and routinely considered when thinking about whether an exoplanet could support life.

https://www.eurekalert.org/news-releases/928771

Related paper:

Potassium isotope composition of Mars reveals a mechanism of planetary volatile retention

Significance

Using spacecraft data and elemental abundances derived from martian meteorites, earlier studies set a paradigm of a volatile- and water-rich Mars relative to Earth. Nevertheless, inherent difficulty in determining the volatile budget of bulk silicate Mars (BSM) makes it challenging to directly compare the extents of volatile depletions among differentiated bodies in the Solar System. This study provides an alternative for evaluating the nature of volatiles on Mars using potassium (K) isotopes. The K isotopic composition of BSM and the strong correlation between δ41K and planet mass reveals that the sizes of planetary bodies fundamentally control their ability to retain volatiles. This could further shed light on the habitability of planets and assist with constraining unknown parent body sizes.

Abstract

The abundances of water and highly to moderately volatile elements in planets are considered critical to mantle convection, surface evolution processes, and habitability. From the first flyby space probes to the more recent “Perseverance” and “Tianwen-1” missions, “follow the water,” and, more broadly, “volatiles,” has been one of the key themes of martian exploration. Ratios of volatiles relative to refractory elements (e.g., K/Th, Rb/Sr) are consistent with a higher volatile content for Mars than for Earth, despite the contrasting present-day surface conditions of those bodies. This study presents K isotope data from a spectrum of martian lithologies as an isotopic tracer for comparing the inventories of highly and moderately volatile elements and compounds of planetary bodies. Here, we show that meteorites from Mars have systematically heavier K isotopic compositions than the bulk silicate Earth, implying a greater loss of K from Mars than from Earth. The average “bulk silicate” δ41K values of Earth, Moon, Mars, and the asteroid 4-Vesta correlate with surface gravity, the Mn/Na “volatility” ratio, and most notably, bulk planet H2O abundance. These relationships indicate that planetary volatile abundances result from variable volatile loss during accretionary growth in which larger mass bodies preferentially retain volatile elements over lower mass objects. There is likely a threshold on the size requirements of rocky (exo)planets to retain enough H2O to enable habitability and plate tectonics, with mass exceeding that of Mars.

https://www.pnas.org/content/118/39/e2101155118
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/21/2021 04:24 pm
Quote
As the inhabitants of an ancient Middle Eastern city now called Tall el-Hammam went about their daily business one day about 3,600 years ago, they had no idea an unseen icy space rock was speeding toward them at about 38,000 mph (61,000 kph).

Flashing through the atmosphere, the rock exploded in a massive fireball about 2.5 miles (4 kilometers) above the ground. The blast was around 1,000 times more powerful than the Hiroshima atomic bomb. The shocked city dwellers who stared at it were blinded instantly. Air temperatures rapidly rose above 3,600 degrees Fahrenheit (2,000 degrees Celsius). Clothing and wood immediately burst into flames. Swords, spears, mudbricks and pottery began to melt. Almost immediately, the entire city was on fire.

Some seconds later, a massive shockwave smashed into the city. Moving at about 740 mph (1,200 kph), it was more powerful than the worst tornado ever recorded. The deadly winds ripped through the city, demolishing every building. They sheared off the top 40 feet (12 m) of the 4-story palace and blew the jumbled debris into the next valley. None of the 8,000 people or any animals within the city survived – their bodies were torn apart and their bones blasted into small fragments.

About a minute later, 14 miles (22 km) to the west of Tall el-Hammam, winds from the blast hit the biblical city of Jericho. Jericho’s walls came tumbling down and the city burned to the ground.

https://theconversation.com/a-giant-space-rock-demolished-an-ancient-middle-eastern-city-and-everyone-in-it-possibly-inspiring-the-biblical-story-of-sodom-167678

Related paper:

A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea

We present evidence that in ~ 1650 BCE (~ 3600 years ago), a cosmic airburst destroyed Tall el-Hammam, a Middle-Bronze-Age city in the southern Jordan Valley northeast of the Dead Sea. The proposed airburst was larger than the 1908 explosion over Tunguska, Russia, where a ~ 50-m-wide bolide detonated with ~ 1000× more energy than the Hiroshima atomic bomb. A city-wide ~ 1.5-m-thick carbon-and-ash-rich destruction layer contains peak concentrations of shocked quartz (~ 5–10 GPa); melted pottery and mudbricks; diamond-like carbon; soot; Fe- and Si-rich spherules; CaCO3 spherules from melted plaster; and melted platinum, iridium, nickel, gold, silver, zircon, chromite, and quartz. Heating experiments indicate temperatures exceeded 2000 °C. Amid city-side devastation, the airburst demolished 12+ m of the 4-to-5-story palace complex and the massive 4-m-thick mudbrick rampart, while causing extreme disarticulation and skeletal fragmentation in nearby humans. An airburst-related influx of salt (~ 4 wt.%) produced hypersalinity, inhibited agriculture, and caused a ~ 300–600-year-long abandonment of ~ 120 regional settlements within a > 25-km radius. Tall el-Hammam may be the second oldest city/town destroyed by a cosmic airburst/impact, after Abu Hureyra, Syria, and possibly the earliest site with an oral tradition that was written down (Genesis). Tunguska-scale airbursts can devastate entire cities/regions and thus, pose a severe modern-day hazard.

https://www.nature.com/articles/s41598-021-97778-3
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/22/2021 04:09 pm
Quote
Astronomers have found a huge cavity in space – and no definite explanation of where it came from.

The vast void is shaped like a sphere, stretches almost 500 light-years across and is found in space among the constellations Perseus and Taurus. The molecular clouds – regions where stars form – that are named after those constellations surround the cavity.

But despite that intriguing fact, scientists have not been able to pin down how exactly the cavity was formed.

https://www.independent.co.uk/space/cavity-supernova-galaxy-void-harvard-b1924841.html

Quote
Unusual signals have led scientists to previously undiscovered galaxies – and there could be many, many more out there waiting to be found.

Scientists have long been looking to find more about the history of the early universe, by looking deep into space. Distant galaxies allow us to see how the universe was much closer to its beginning, effectively allowing astronomers to look back in time.

https://www.independent.co.uk/space/signals-galaxies-early-universe-dust-b1924938.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/23/2021 10:26 am
Quote
THE EIGHT PLANETS of our Solar System aren’t the only ones we’ve ever had — they’re merely the survivors.

But that doesn’t mean the other planets were destroyed. Earth may have a long-lost sibling somewhere in interstellar space. At least one rocky planet, around the same mass as Mars, may have been booted out of the early Solar System.

Quote
The rogue planet scenario isn’t to be confused with Planet Nine, a much larger hypothetical planet that some planetary scientists suggest may be awaiting discovery even further out in trans-Neptunian space.

https://www.inverse.com/science/earth-missing-twin

Transneptunian Space

Abstract

We provide a nonspecialist overview of the current state of understanding of the structure and origin of our Solar System's transneptunian region (often called the Kuiper Belt), highlighting perspectives on planetesimal formation, planet migration, and the contextual relationship with protoplanetary disks. We review the dynamical features of the transneptunian populations and their associated differences in physical properties. We describe aspects of our knowledge that have advanced in the past two decades and then move on to current issues of research interest (which thus still have unclear resolution).


The current transneptunian population consists of both implanted and primordial objects.


The primordial (aka cold) population is a largely unaltered remnant of the population that formed in situ.


The reason for the primordial cold population's current outer edge is unexplained.


The large semimajor-axis population now dynamically detached from Neptune is critical for understanding the Solar System's history.


Observational constraints on the number and orbits of distant objects remain poor.

https://www.annualreviews.org/doi/10.1146/annurev-astro-120920-010005
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 09/23/2021 11:09 am
A new study shows that they have been better able to describe this huge comet.

C/2014 UN271 (Bernardinelli-Bernstein): the nearly spherical cow of comets

C/2014 UN271 (Bernardinelli-Bernstein) is a comet incoming from the Oort cloud which is remarkable in having the brightest (and presumably largest) nucleus of any well-measured comet, and having been discovered at heliocentric distance rh≈29 au farther than any Oort-cloud member. We describe the properties that can be inferred from images recorded until the first reports of activity in June 2021. The orbit has i=95, with perihelion of 10.97 au to be reached in 2031, and previous aphelion at 40,400±260 au. Backwards integration of the orbit under a standard Galactic tidal model and known stellar encounters suggests this is a pristine new comet, with a perihelion of q≈18 au on its previous perihelion passage 3.5 Myr ago. The photometric data show an unresolved nucleus with absolute magnitude Hr=8.0, colors that are typical of comet nuclei or Damocloids, and no secular trend as it traversed the range 34--23 au. For r-band geometric albedo pr, this implies a diameter of 150(pr/0.04)−0.5 km. There is strong evidence of brightness fluctuations at ±0.2 mag level, but no rotation period can be discerned. A coma consistent with a ``stationary' 1/ρ surface-brightness distribution grew in scattering cross-section at an exponential rate from Afρ≈1 m to ≈150 m as the comet approached from 28 to 20 au. The activity is consistent with a simple model of sublimation of a surface species in radiative equilibrium with the Sun. The inferred enthalpy of sublimation matches those of CO2 and NH3. More-volatile species -- N2, CH4, and CO -- must be far less abundant on the sublimating surfaces.

https://arxiv.org/abs/2109.09852
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/29/2021 08:20 am
WASP-127b: A misaligned planet with a partly cloudy atmosphere and tenuous sodium signature seen by ESPRESSO

The study of exoplanet atmospheres is essential to understand the formation, evolution and composition of exoplanets. The transmission spectroscopy technique is playing a significant role in this domain. In particular, the combination of state-of-the-art spectrographs at low- and high-spectral resolution is key to our understanding of atmospheric structure and composition. Two transits of the close-in sub Saturn-mass planet,WASP-127b, have been observed with ESPRESSO in the frame of the Guaranteed Time Observations Consortium. Transit observations allow us to study simultaneously the system architecture and the exoplanet atmosphere. We found that this planet is orbiting its slowly rotating host star (veq sin(i)=0.53+/-0.07 km/s) on a retrograde misaligned orbit (lambda=-128.41+/-5.60 deg). We detected the sodium line core at the 9-sigma confidence level with an excess absorption of 0.3+/-0.04%, a blueshift of 2.7+/-0.79 km/s and a FWHM of 15.18+/-1.75 km/s. However, we did not detect the presence of other atomic species but set upper-limits of only few scale heights. Finally, we put a 3-sigma upper limit, to the average depth of the 1600 strongest water lines at equilibrium temperature in the visible band, of 38 ppm. This constrains the cloud-deck pressure between 0.3 and 0.5 mbar by combining our data with low-resolution data in the near-infrared and models computed for this planet. To conclude, WASP-127b, with an age of about 10 Gyr, is an unexpected exoplanet by its orbital architecture but also by the small extension of its sodium atmosphere (~7 scale heights). ESPRESSO allows us to take a step forward in the detection of weak signals, thus bringing strong constraints on the presence of clouds in exoplanet atmospheres. The framework proposed in this work can be applied to search for molecular species and study cloud-decks in other exoplanets.

https://arxiv.org/abs/2010.15143
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/01/2021 08:33 am
Modons on Tidally Synchronised Extrasolar Planets

We investigate modons on tidally synchronised extrasolar planets. Modons are highly dynamic, coherent flow structures composed of a pair of storms with opposite signs of vorticity. They are important because they divert flows on the large-scale; and, powered by the intense irradiation from the host star, they are planetary-scale sized and exhibit quasi-periodic life-cycles -- chaotically moving around the planet, breaking and reforming many times over long durations (e.g. thousands of planet days). Additionally, modons transport and mix planetary-scale patches of hot and cold air around the planet, leading to high-amplitude and quasi-periodic signatures in the disc-averaged temperature flux. Hence, they induce variations of the "hot spot" longitude to either side of the planet's sub-stellar point -- consistent with observations at different epoch. The variability behaviour in our simulations broadly underscores the importance of accurately capturing vortex dynamics in extrasolar planet atmosphere modelling, particularly in understanding current observations.

https://arxiv.org/abs/2109.06568
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/02/2021 07:00 am
Study Finds Photosynthesis in Venus’ Clouds Could Support Life

Quote
New data analysis has found that the sunlight filtering through Venus’ clouds could support Earth-like photosynthesis in the cloud layers and that chemical conditions are potentially amenable to the growth of microorganisms.

https://polycentric.cpp.edu/2021/09/study-finds-photosynthesis-in-venus-clouds-could-support-life/

Potential for Phototrophy in Venus' Clouds

Abstract

We show that solar irradiances calculated across Venus' clouds support the potential for Earth-like phototrophy and that treatment of Venus' aerosols containing neutralized sulfuric acid favor a habitable zone. The phototrophic potential of Venus' atmosphere was assessed by calculating irradiances (200–2000 nm, 15° solar zenith angle, local noon) using a radiative transfer model that accounted for absorption and scattering by the major and minor atmospheric constituents. Comparisons to Earth's surface (46 W m−2, 280–400 nm) suggest that Venus' middle and lower clouds receive ∼87% less normalized UV flux (6–7 W m−2) across 200–400 nm, yet similar normalized photon flux densities (∼4400–6200 μmol m−2 s−1) across 350–1200 nm. Further, Venus' signature phototrophic windows and subwindows overlap with the absorption profiles of several photosynthetic pigments, especially bacteriochlorophyll b from intact cells and phycocyanin. Therefore, Venus' light, with limited UV flux in the middle and lower clouds, is likely quite favorable for phototrophy. We additionally present interpretations to refractive index and radio occultation measures for Venus' aerosols that suggest the presence of lower sulfuric abundances and/or neutralized forms of sulfuric acid, such as ammonium bisulfate. Under these considerations, the aerosols in Venus' middle clouds could harbor water activities (≥0.6) and buffered acidities (Hammett acidity factor, H0 -0.1 to -1.5) that lie within the limits of acidic cultivation (≥H0 -0.4) and are tantalizingly close to the limits of oxygenic photosynthesis (≥H0 0.1). Together, these photophysical and chemical considerations support a potential for phototrophy in Venus' clouds.

https://www.liebertpub.com/doi/full/10.1089/ast.2021.0032
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/02/2021 06:37 pm
GW Ori: circumtriple rings and planets

ABSTRACT
GW Ori is a hierarchical triple star system with a misaligned circumtriple protoplanetary disc. Recent Atacama Large Millimeter/submillimeter Array observations have identified three dust rings with a prominent gap at 100au
 and misalignments between each of the rings. A break in the gas disc may be driven by the torque from either the triple star system or a planet that is massive enough to carve a gap in the disc. Once the disc is broken, the rings nodally precess on different time-scales and become misaligned. We investigate the origins of the dust rings by means of N-body integrations and 3D hydrodynamic simulations. We find that for observationally motivated parameters of protoplanetary discs, the disc does not break due to the torque from the star system. We suggest that the presence of a massive planet (or planets) in the disc separates the inner and outer discs. We conclude that the disc breaking in GW Ori is likely caused by undetected planets – the first planet(s) in a circumtriple orbit.

https://academic.oup.com/mnras/article-abstract/508/1/392/6371904?redirectedFrom=fulltext
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/11/2021 07:40 am
Energy burst from most distant known galaxy might have been a satellite orbiting Earth

Quote
Gamma rays are one of the most energetic forms of light, and gamma ray bursts release almost unimaginable quantities of them. First discovered during the cold war – by military satellites searching for the signs of nuclear tests in the upper atmosphere – gamma ray bursts are now thought to be caused by massive stars undergoing huge explosions when they run out of fuel. These events are rare, but so energetic they can be seen in galaxies many billions of light years away.

Recently, astronomers thought they had seen evidence for one of these explosions from the most distant galaxy every seen. But a recently published paper casts doubt on these claims, suggesting it might have been caused by a more mundane source much closer to home.

Quote
Around the time that the original team were studying the sky, a Russian proton rocket reached low Earth orbit and released its upper stages (dubbed Breeze-M), which then became space junk, orbiting the Earth. By looking at the orbit of the space debris and matching with the observations taken in the original study, the new team found the flash could be simply explained by the upper stage falling past the part of the sky the telescope was observing.

https://theconversation.com/energy-burst-from-most-distant-known-galaxy-might-have-been-a-satellite-orbiting-earth-159171

Related paper:

GN-z11-flash from a man-made satellite not a gamma-ray burst at redshift 11

https://www.nature.com/articles/s41550-021-01472-3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/12/2021 02:09 pm
Meet 42 Asteroids in Our Solar System (ESOcast 243 Light):

https://youtu.be/dMrTgD1mYEQ
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/12/2021 04:50 pm
Astronomers discover 'extraordinary' unknown radio signal from heart of Milky Way

Quote
Across the vast desert plains of Western Australia, on the lands of the Wajarri Yamatji people, lies one of the most capable radio telescope arrays in the world. Containing 36 dish antennas, the Australian Square Kilometre Array Pathfinder, ASKAP, is an eye to the universe. The three dozen antennas watch for radio waves that crash over the Earth.

Over the last two years the antennas have, on occasion, been pointed toward the heart of the Milky Way, our home galaxy. And, on occasion, they've detected a highly unusual radio signal -- one that does not seem to fit with any object we currently know is lurking in the cosmos.

The detection of the signal appears in the Astrophysical Journal on Oct. 12. It was first published as a preprint on arXiv in September.

The name of the strange signal is a mouthful: ASKAP J173608.2-321635. We're going to call it the Ghost. Between April 2019 and August 2020, the Ghost was spotted 13 times but without any consistent timing.

https://www.cnet.com/news/astronomers-discover-extraordinary-unknown-radio-signal-from-heart-of-milky-way/

Here’s the related paper:

https://arxiv.org/pdf/2109.00652.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/15/2021 07:16 am
The population of M dwarfs observed at low radio frequencies

Abstract
Coherent low-frequency (200 MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events and space weather1,2,3,4,5. Previous low-frequency searches for radio-emitting stellar systems have lacked the sensitivity to detect the general population, instead largely focusing on targeted studies of anomalously active stars5,6,7,8,9. Here we present 19 detections of coherent radio emission associated with known M dwarfs from a blind flux-limited low-frequency survey. Our detections show that coherent radio emission is ubiquitous across the M dwarf main sequence, and that the radio luminosity is independent of known coronal and chromospheric activity indicators. While plasma emission can generate the low-frequency emission from the most chromospherically active stars of our sample1,10, the origin of the radio emission from the most quiescent sources is yet to be ascertained. Large-scale analogues of the magnetospheric processes seen in gas giant planets3,11,12 probably drive the radio emission associated with these quiescent stars. The slowest-rotating stars of this sample are candidate systems to search for star–planet interaction signatures.

https://www.nature.com/articles/s41550-021-01483-0

Source: https://www.popsci.com/space/radio-signals-exoplanets/
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 10/21/2021 07:08 am
Probably stretching the terms of this thread but I thought this was interesting.

Quote
In A.D. 993, a storm on the sun released an enormous pulse of radiation that was absorbed and stored by trees all over the Earth. Now, that solar event has proved a critical tool in pinpointing an exact year the Vikings were present in the Americas.

Quote
There was one more thing that stood out: Three of the wood samples were from trees alive during the solar event of 993, when the cosmic storm released a pulse of radiation so powerful that it was recorded in the rings of the world’s trees. Referred to by researchers as a “cosmogenic radiocarbon event,” the phenomenon has only happened twice in the last 2,000 years.

https://www.nationalgeographic.com/history/article/ancient-solar-storm-pinpoints-viking-settlement-americas-exactly-1000-years-ago
Title: Astronomy & Planetary Science Thread
Post by: Star One on 10/25/2021 03:32 pm
A Stable H2O Atmosphere on Europa’s Trailing Hemisphere From HST Images

Abstract

Previous studies of the global intensities of the oxygen emissions at 1,356 Å and 1,304 Å revealed molecular oxygen (O2) in Europa's atmosphere. Here we investigate the relative changes of the two oxygen emissions when Europa emerges from eclipse as well as the radial profiles of the relative emissions across the sunlit disk in Hubble Space Telescope observations taken in 1999, 2012, 2014, and 2015 while the moon was at various orbital positions. The eclipse observation constrains the atomic oxygen (O) column density to urn:x-wiley:00948276:media:grl63016:grl63016-math-0001 urn:x-wiley:00948276:media:grl63016:grl63016-math-0002 or lower. We then find that the OI1356-Å/OI1304-Å ratio systematically decreases towards the disk center on the trailing hemisphere. The observed emission ratio pattern and the persistence of it from 1999 to 2015 imply a stable H2O abundance in the central sunlit trailing hemisphere with an H2O/O2 ratio of 12–22. On the leading hemisphere, the emissions are consistent with a pure O2 atmosphere everywhere across the moon disk.
Plain Language Summary

Observations by the Hubble Space Telescope in far-ultraviolet light of Jupiter's icy moons were used in the past to detect their oxygen atmospheres. Results of a new analysis of images and spectra of the moon Ganymede have recently shown that the same observations also contain information that water vapor is abundant in the atmosphere in addition to oxygen. We use the same analysis here for Europa and find a water vapor atmosphere as well, but only above the orbital trailing hemisphere of the moon.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL094289
Title: Re: Astronomy & Planetary Science Thread
Post by: Dinamobolso on 10/25/2021 07:24 pm
https://www.visualcapitalist.com/a-visual-introduction-to-the-dwarf-planets-in-our-solar-system/ (https://www.visualcapitalist.com/a-visual-introduction-to-the-dwarf-planets-in-our-solar-system/)

A good animation of dwarf planet.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/26/2021 06:51 am
Unfortunately the link in this article to the related paper is broken.

Signs of an extreme planet found in another galaxy

Quote
In a study published today in the journal Nature Astronomy, researchers led by astrophysicist Rosanne Di Stefano argue that M51-ULS-1, the x-ray binary system within the Whirlpool Galaxy, may host a Saturn-size planet that orbits as far from the binary as Uranus does from our sun.

If this planet really exists, M51-ULS-1 would mark the first pinpointed star system in another galaxy that has an “extroplanet,” or a planet found outside of our home galaxy, the Milky Way.

https://www.nationalgeographic.com/science/article/signs-of-an-extreme-planet-found-in-another-galaxy
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/27/2021 07:38 am
Not so fast on those claims of having discovered the first exoplanet outside the Milky Way.

Quote
"Either this is a completely unexpected exoplanet discovered almost immediately in a small amount of data or it's something quite common or garden variety," says Benjamin Pope, an astrophysicist studying exoplanets at the University of Queensland in Australia.

Quote
Pope is less convinced. "Personally, I wouldn't bet that this is a planet," he says. "In my view this is probably a stellar companion or something exotic happening in the disk."

Quote
Pope notes that if we found analogous systems in the Milky Way, we'd be able to follow up with optical telescopes and get a better understanding of what might be happening at these types of systems.

We know there must be planets outside of the Milky Way and so, eventually, humans will discover them. For Galloway, the study is exciting not because of what caused the X-ray binary to dip in brightness, but what happens next.

"The really exciting thing is there might be additional events in other data, so now we have a motivation where we can go and look for them," he says.

https://www.cnet.com/news/have-scientists-found-the-first-planet-outside-our-galaxy-its-complicated/
Title: Re: Astronomy & Planetary Science Thread
Post by: AnalogMan on 10/27/2021 10:49 am
Unfortunately the link in this article to the related paper is broken.

Signs of an extreme planet found in another galaxy

[...]

Try this link:

A possible planet candidate in an external galaxy detected through X-ray transit
https://www.nature.com/articles/s41550-021-01495-w/ (https://www.nature.com/articles/s41550-021-01495-w/)

(copy of pdf attached)


Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/27/2021 04:15 pm
Quote
While analyzing some of the world's oldest coloured gemstones, researchers from the University of Waterloo discovered carbon residue that was once ancient life, encased in a 2.5 billion-year-old ruby.

https://www.sciencedaily.com/releases/2021/10/211021084608.htm
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/04/2021 07:40 pm
Strange Signals Coming From the Center of The Galaxy with Dr. Tara Murphy:

https://youtu.be/KK4bbCsTbT8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/07/2021 07:33 am
The First Astronomers

For thousands of years indigenous Australians, the longest living culture on Earth, have been fascinated by the stars. In this episode Kamilaroi man and ANU astrophysics graduate Peter Swanton shines a light on the great depth of knowledge indigenous Australians associate with various constellations: from the multi-layered story about the Southern Cross to the unique study of the Dark Emu to how Torres Strait islanders used the phases of the Moon for weather predictions and seasons.

https://play.acast.com/s/the-ancients/thefirstastronomers
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/10/2021 02:24 pm
A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone

Abstract
Cosmic rays are important probe of a number of fundamental physical problems such as the acceleration of high and very high energy particles in extreme astrophysical environments. The Galactic center is widely anticipated to be an important cosmic-ray source and the observations of some Imaging Atmospheric Cherenkov Telescopes did successfully reveal a component of TeV-PeV cosmic rays in the vicinity of the Galactic center. Here we report the identification of GeV-TeV cosmic rays in the central molecular zone with the γ-ray observations of the Fermi Large Area Telescope, whose spectrum and spatial gradient are consistent with that measured by the Imaging Atmospheric Cherenkov Telescopes but the corresponding cosmic-ray energy density is substantially lower than the so-called cosmic-ray sea component, suggesting the presence of a high energy particle accelerator at the Galactic center and the existence of a barrier that can effectively suppress the penetration of the particles from the cosmic-ray sea to the central molecular zone.

https://www.nature.com/articles/s41467-021-26436-z

Source: https://phys.org/news/2021-11-fermi-large-area-telescope-particle.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/11/2021 04:23 pm
Black Hole Discovered in Galaxy Next Door (ESOcast 245 light):

https://youtu.be/qW-HXYXYybk

For the first time, astronomers have discovered a small black hole outside the Milky Way by looking at how it influences the motion of a star in its close vicinity. This video summarises the discovery.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/17/2021 02:49 pm
A mysterious ‘superbubble’ carved in the heart of a glowing emission nebula

https://astronomynow.com/2021/11/03/a-mysterious-superbubble-carved-in-the-heart-of-a-glowing-emission-nebula/
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/18/2021 07:28 am
It seems that the search for life on Mars could easily be misled by geological processes.

False biosignatures on Mars: anticipating ambiguity

Abstract

It is often acknowledged that the search for life on Mars might produce false positive results, particularly via the detection of objects, patterns or substances that resemble the products of life in some way but are not biogenic. The success of major current and forthcoming rover missions now calls for significant efforts to mitigate this risk. Here, we review known processes that could have generated false biosignatures on early Mars. These examples are known largely from serendipitous discoveries rather than systematic research and remain poorly understood; they probably represent only a small subset of relevant phenomena. These phenomena tend to be driven by kinetic processes far from thermodynamic equilibrium, often in the presence of liquid water and organic matter, conditions similar to those that can actually give rise to, and support, life. We propose that strategies for assessing candidate biosignatures on Mars could be improved by new knowledge on the physics and chemistry of abiotic self-organization in geological systems. We conclude by calling for new interdisciplinary research to determine how false biosignatures may arise, focusing on geological materials, conditions and spatiotemporal scales relevant to the detection of life on Mars, as well as the early Earth and other planetary bodies.

https://jgs.lyellcollection.org/content/early/2021/10/07/jgs2021-050
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/25/2021 05:03 pm
An upper limit on late accretion and water delivery in the TRAPPIST-1 exoplanet system

Abstract
The TRAPPIST-1 system contains seven roughly Earth-sized planets locked in a multiresonant orbital configuration1,2, which has enabled precise measurements of the planets’ masses and constrained their compositions3. Here we use the system’s fragile orbital structure to place robust upper limits on the planets’ bombardment histories. We use N-body simulations to show how perturbations from additional objects can break the multiresonant configuration by either triggering dynamical instability or simply removing the planets from resonance. The planets cannot have interacted with more than ~5% of one Earth mass (M⊕) in planetesimals—or a single rogue planet more massive than Earth’s Moon—without disrupting their resonant orbital structure. This implies an upper limit of 10−4 M⊕ to 10−2 M⊕ of late accretion on each planet since the dispersal of the system’s gaseous disk. This is comparable to (or less than) the late accretion on Earth after the Moon-forming impact4,5, and demonstrates that the growth of the TRAPPIST-1 planets was complete in just a few million years, roughly an order of magnitude faster than that of the Earth6,7. Our results imply that any large water reservoirs on the TRAPPIST-1 planets must have been incorporated during their formation in the gaseous disk.

https://www.nature.com/articles/s41550-021-01518-6

Source: https://phys.org/news/2021-11-orbital-harmony-limits-late-trappist-.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/26/2021 04:46 pm
The HD 137496 system: A dense, hot super-Mercury and a cold Jupiter

Most of the currently known planets are small worlds with radii between that of the Earth and that of Neptune. The characterization of planets in this regime shows a large diversity in compositions and system architectures, with distributions hinting at a multitude of formation and evolution scenarios. Using photometry from the K2 satellite and radial velocities measured with the HARPS and CORALIE spectrographs, we searched for planets around the bright and slightly evolved Sun-like star HD 137496. We precisely estimated the stellar parameters, M∗ = 1.035 +/- 0.022 M, R∗ = 1.587 +/- 0.028 R, Teff = 5799 +/- 61 K, together with the chemical composition of the slightly evolved star. We detect two planets orbiting HD 137496. The inner planet, HD 137496 b, is a super-Mercury (an Earth-sized planet with the density of Mercury) with a mass of Mb = 4.04 +/- 0.55 M⊕, a radius of Rb=1.31+0.06−0.05R⊕, and a density of ρb=10.49+2.08−1.82 gcm−3. With an interior modeling analysis, we find that the planet is composed mainly of iron, with the core representing over 70% of the planet's mass (Mcore/Mtotal=0.73+0.11−0.12). The outer planet, HD 137496 c, is an eccentric (e = 0.477 +/- 0.004), long period (P = 479.9+1.0−1.1 days) giant planet (Mcsinic = 7.66 +/- 0.11 MJup) for which we do not detect a transit. HD 137496 b is one of the few super-Mercuries detected to date. The accurate characterization reported here enhances its role as a key target to better understand the formation and evolution of planetary systems. The detection of an eccentric long period giant companion also reinforces the link between the presence of small transiting inner planets and long period gas giants.

https://arxiv.org/abs/2111.08764
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2021 04:53 pm
Solar wind contributions to Earth’s oceans

Abstract
The isotopic composition of water in Earth’s oceans is challenging to recreate using a plausible mixture of known extraterrestrial sources such as asteroids—an additional isotopically light reservoir is required. The Sun’s solar wind could provide an answer to balance Earth’s water budget. We used atom probe tomography to directly observe an average ~1 mol% enrichment in water and hydroxyls in the solar-wind-irradiated rim of an olivine grain from the S-type asteroid Itokawa. We also experimentally confirm that H+ irradiation of silicate mineral surfaces produces water molecules. These results suggest that the Itokawa regolith could contain ~20 l m−3 of solar-wind-derived water and that such water reservoirs are probably ubiquitous on airless worlds throughout our Galaxy. The production of this isotopically light water reservoir by solar wind implantation into fine-grained silicates may have been a particularly important process in the early Solar System, potentially providing a means to recreate Earth’s current water isotope ratios.

https://www.nature.com/articles/s41550-021-01487-w

Quote
Curtin graduate Dr. Luke Daly, now of the University of Glasgow, said the research not only gives scientists a remarkable insight into the past source of Earth's water, but could also help future space missions.

"How astronauts would get sufficient water, without carrying supplies, is one of the barriers of future space exploration," Dr. Daly said.

"Our research shows that the same space weathering process which created water on Itokawa likely occurred on other airless planets, meaning astronauts may be able to process fresh supplies of water straight from the dust on a planet's surface, such as the Moon."

https://phys.org/news/2021-11-sun-unaccounted-source-earth.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/02/2021 02:22 pm
Supermassive Black Holes on a Collision Course (ESOcast 246 Light)

https://youtu.be/GfNQfUloEyA

Quote
Using the ESO’s Very Large Telescope, astronomers have revealed the closest pair of supermassive black holes to Earth ever observed. This video summarises the discovery.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/08/2021 02:52 pm
NASA’s Next-Generation Asteroid Impact Monitoring System Goes Online

The new system improves the capabilities of NASA JPL’s Center for Near Earth Object Studies to assess the impact risk of asteroids that can come close to our planet.

To date, nearly 28,000 near-Earth asteroids (NEAs) have been found by survey telescopes that continually scan the night sky, adding new discoveries at a rate of about 3,000 per year. But as larger and more advanced survey telescopes turbocharge the search over the next few years, a rapid uptick in discoveries is expected. In anticipation of this increase, NASA astronomers have developed a next-generation impact monitoring algorithm called Sentry-II to better evaluate NEA impact probabilities.

Popular culture often depicts asteroids as chaotic objects that zoom haphazardly around our solar system, changing course unpredictably and threatening our planet without a moment’s notice. This is not the reality. Asteroids are extremely predictable celestial bodies that obey the laws of physics and follow knowable orbital paths around the Sun.

But sometimes, those paths can come very close to Earth’s future position and, because of small uncertainties in the asteroids’ positions, a future Earth impact cannot be completely ruled out. So, astronomers use sophisticated impact monitoring software to automatically calculate the impact risk.

Managed by NASA’s Jet Propulsion Laboratory in Southern California, the Center for Near Earth Object Studies (CNEOS) calculates every known NEA orbit to improve impact hazard assessments in support of NASA’s Planetary Defense Coordination Office (PDCO). CNEOS has monitored the impact risk posed by NEAs with software called Sentry, developed by JPL in 2002.

“The first version of Sentry was a very capable system that was in operation for almost 20 years,” said Javier Roa Vicens, who led the development of Sentry-II while working at JPL as a navigation engineer and recently moved to SpaceX. “It was based on some very smart mathematics: In under an hour, you could reliably get the impact probability for a newly discovered asteroid over the next 100 years – an incredible feat.”

But with Sentry-II, NASA has a tool that can rapidly calculate impact probabilities for all known NEAs, including some special cases not captured by the original Sentry. Sentry-II reports the objects of most risk in the CNEOS Sentry Table.

By systematically calculating impact probabilities in this new way, the researchers have made the impact monitoring system more robust, enabling NASA to confidently assess all potential impacts with odds as low as a few chances in 10 million.

Special Cases

As an asteroid travels through the solar system, the Sun’s gravitational pull dictates the path of its orbit, and the gravity of the planets will also tug at its trajectory in predictable ways. Sentry modeled to a high precision how these gravitational forces shaped an asteroid’s orbit, helping to predict where it will be far into the future. But it couldn’t account for non-gravitational forces, the most significant being the thermal forces caused by the Sun’s heat. 

As an asteroid spins, sunlight heats the object’s dayside. The heated surface will then rotate to the asteroid’s shaded nightside and cool down. Infrared energy is released as it cools, generating a tiny yet continual thrust on the asteroid. This phenomenon is known as the Yarkovsky effect, which has little influence on the asteroid’s motion over short periods but can significantly change its path over decades and centuries.

https://youtu.be/Cb9IL8AqrGA

This video explains how asteroid Bennu’s orbit around the Sun was determined by considering gravitational and non-gravitational forces, helping scientists understand how the asteroid’s trajectory will change over time.
Credits: NASA’s Goddard Space Flight Center
“The fact that Sentry couldn’t automatically handle the Yarkovsky effect was a limitation,” said Davide Farnocchia, a navigation engineer at JPL who also helped develop Sentry-II. “Every time we came across a special case – like asteroids Apophis, Bennu, or 1950 DA – we had to do complex and time-consuming manual analyses. With Sentry-II, we don’t have to do that anymore.”

Another issue with the original Sentry algorithm was that it sometimes couldn’t accurately predict the impact probability of asteroids that undergo extremely close encounters with Earth. The motion of these NEAs gets significantly deflected by our planet’s gravity, and the post-encounter orbital uncertainties can grow dramatically. In those cases, the old Sentry’s calculations could fail, requiring manual intervention. Sentry-II doesn’t have that limitation.

“In terms of numbers, the special cases we’d find were a very tiny fraction of all the NEAs that we’d calculate impact probabilities for,” said Roa Vicens. “But we are going to discover many more of these special cases when NASA’s planned NEO Surveyor mission and the Vera C. Rubin Observatory in Chile go online, so we need to be prepared.”

Many Needles, One Haystack

This is how impact probabilities are calculated: When telescopes track a new NEA, astronomers measure the asteroid’s observed positions in the sky and report them to the Minor Planet Center. CNEOS then uses that data to determine the asteroid’s most likely orbit around the Sun. But because there are slight uncertainties in the asteroid’s observed position, its “most likely orbit” might not represent its true orbit. The true orbit is somewhere inside an uncertainty region, like a cloud of possibilities surrounding the most likely orbit.

To assess whether an impact is possible and narrow down where the true orbit may be, the original Sentry would make some assumptions as to how the uncertainty region may evolve. It would then select a set of evenly spaced points along a line spanning the uncertainty region. Each point represented a slightly different possible current location of the asteroid.

Sentry would then wind the clock forward, watch those “virtual asteroids” orbit the Sun, and see if any came near Earth in the future. If so, further calculations would be required to “zoom in” to see whether any intermediate points might impact Earth, and if they did, estimate the impact probability.

https://youtu.be/t94moJHoL2w

This animation shows an example of how the uncertainties in a near-Earth asteroid’s orbit can evolve with time. After such an asteroid’s close encounter with Earth, the uncertainty region becomes larger, making the possibility of future impacts more challenging to assess.
Credits: NASA/JPL-Caltech
Sentry-II has a different philosophy. The new algorithm models thousands of random points not limited by any assumptions about how the uncertainty region may evolve; instead, it selects random points throughout the entire uncertainty region. Sentry-II’s algorithm then asks: What are the possible orbits within the entire region of uncertainty that could hit Earth?

This way, the orbital determination calculations aren’t shaped by predetermined assumptions about which portions of the uncertainty region might lead to a possible impact. This allows Sentry-II to zero in on more very low probability impact scenarios, some of which Sentry may have missed.

Farnocchia likens the process to searching for needles in a haystack: The needles are possible impact scenarios, and the haystack is the uncertainty region. The more the uncertainty in an asteroid’s position, the bigger the haystack. Sentry would randomly poke at the haystack thousands of times looking for needles located near a single line stretching through the haystack. The assumption was that following this line was the best way of searching for needles. But Sentry-II assumes no line and instead throws thousands of tiny magnets randomly all over that haystack, which quickly get attracted to, and then find, the nearby needles.

“Sentry-II is a fantastic advancement in finding tiny impact probabilities for a huge range of scenarios,” said Steve Chesley, senior research scientist at JPL, who led the development of Sentry and collaborated on Sentry-II. “When the consequences of a future asteroid impact are so big, it pays to find even the smallest impact risk hiding in the data.”

A study describing Sentry-II was published in the Astronomical Journal on Dec. 1, 2021.

More information about CNEOS, asteroids, and near-Earth objects can be found at:

https://cneos.jpl.nasa.gov

For more information about PDCO, visit:

https://www.nasa.gov/planetarydefense
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/08/2021 08:16 pm
Surprise planet found around extreme star pair (ESOcast 247 Light):

https://youtu.be/JuOz9QY6mjI
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/09/2021 05:04 pm
A young, sun-like star may hold warnings for life on Earth

Quote
Astronomers spying on a stellar system located dozens of lightyears from Earth have, for the first time, observed a troubling fireworks show: A star, named EK Draconis, ejected a massive burst of energy and charged particles much more powerful than anything scientists have seen in our own solar system.

Quote
Still, Notsu noted that huge mass ejections may have been much more common in the early years of the solar system. Gigantic coronal mass ejections, in other words, could have helped to shape planets like Earth and Mars into what they look like today.

“The atmosphere of present-day Mars is very thin compared to Earth’s,” Notsu said. “In the past, we think that Mars had a much thicker atmosphere. Coronal mass ejections may help us to understand what happened to the planet over billions of years.”

https://www.colorado.edu/today/2021/12/09/ek-draconis

Related paper:

Probable detection of an eruptive filament from a superflare on a solar-type star

Abstract
Solar flares are often accompanied by filament/prominence eruptions (~104 K and ~1010−11 cm−3), sometimes leading to coronal mass ejections that directly affect the Earth’s environment1,2. ‘Superflares’ are found on some active solar-type (G-type main-sequence) stars3,4,5, but the filament eruption–coronal mass ejection association has not been established. Here we show that our optical spectroscopic observation of the young solar-type star EK Draconis reveals evidence for a stellar filament eruption associated with a superflare. This superflare emitted a radiated energy of 2.0 × 1033 erg, and a blueshifted hydrogen absorption component with a high velocity of −510 km s−1 was observed shortly afterwards. The temporal changes in the spectra strongly resemble those of solar filament eruptions. Comparing this eruption with solar filament eruptions in terms of the length scale and velocity strongly suggests that a stellar coronal mass ejection occurred. The erupted filament mass of 1.1 × 1018 g is ten times larger than those of the largest solar coronal mass ejections. The massive filament eruption and an associated coronal mass ejection provide the opportunity to evaluate how they affect the environment of young exoplanets/the young Earth6 and stellar mass/angular momentum evolution7.

https://www.nature.com/articles/s41550-021-01532-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/09/2021 08:27 pm
NASA Goddard - Mini-Jet Found Near Milky Way’s Supermassive Black Hole:

https://youtu.be/zxqQ4G0NOhI
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/13/2021 07:21 am
Quote
The existence of carbon dioxide (CO2) cold traps on the Moon has been confirmed, offering a potential resource for future exploration of the lunar surface, according to a new paper by Planetary Science Institute Senior Scientist Norbert Schorghofer.

https://psi.edu/news/lunarco2coldtraps

Related paper:

Carbon Dioxide Cold Traps on the Moon

Abstract
Water ice is expected to be trapped in permanently cold regions near the lunar poles. Other ices (“super-volatiles”) are trapped at lower temperatures, close to the lowest temperatures measured within the lunar permanently shadowed regions (PSRs). Here, the thermal stability of solid carbon dioxide in the south polar region is determined by analysis of 11 years of temperature measurements by Diviner, a radiometer onboard the Lunar Reconnaissance Orbiter. Sublimation rates averaged over a draconic year are far lower than peak sublimation rates. Small spatially contiguous pockets of CO2 ice stability are found in the craters Amundsen, Haworth, de Gerlache, and others, over a cumulative area of roughly 200 km2. The LCROSS probe impacted one of those pockets and released CO2, serving as validation of the thermal stability calculations. Future surface missions can utilize this highly localized resource for the production of fuel, steel, and biological materials.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL095533
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/13/2021 07:48 pm
Quote
In June of 2018, telescopes around the world picked up a brilliant blue flash from the spiral arm of a galaxy 200 million light years away. The powerful burst appeared at first to be a supernova, though it was much faster and far brighter than any stellar explosion scientists had yet seen. The signal, procedurally labeled AT2018cow, has since been dubbed simply “the Cow,” and astronomers have catalogued it as a fast blue optical transient, or FBOT — a bright, short-lived event of unknown origin.

Now an MIT-led team has found strong evidence for the signal’s source. In addition to a bright optical flash, the scientists detected a strobe-like pulse of high-energy X-rays. They traced hundreds of millions of such X-ray pulses back to the Cow, and found the pulses occurred like clockwork, every 4.4 milliseconds, over a span of 60 days.

Based on the frequency of the pulses, the team calculated that the X-rays must have come from an object measuring no more than 1,000 kilometers wide, with a mass smaller than 800 suns. By astrophysical standards, such an object would be considered compact, much like a small black hole or a neutron star.

https://news.mit.edu/2021/stellar-black-hole-neutron-star-1213

https://youtu.be/NSZIewPb0zU
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/14/2021 07:41 pm
Watch Stars Move Around our Galaxy’s Central Black Hole (ESOcast 248 Light):

https://youtu.be/QZapi-pavhs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/20/2021 04:03 pm
A Harsh Test of Far-Field Scrambling with the Habitable Zone Planet Finder and the Hobby Eberly Telescope

The Habitable zone Planet Finder (HPF) is a fiber fed precise radial velocity spectrograph at the 10 m Hobby Eberly Telescope (HET). Due to its fixed altitude design, the HET pupil changes appreciably across a track, leading to significant changes of the fiber far-field illumination. HPF's fiber scrambler is designed to suppress the impact of these illumination changes on the radial velocities -- but the residual impact on the radial velocity measurements has yet to be probed on sky. We use GJ 411, a bright early type (M2) M dwarf to probe the effects of far-field input trends due to these pupil variations on HPF radial velocities (RVs). These large changes (∼ 2x) in pupil area and centroid present a harsh test of HPF's far-field scrambling. Our results show that the RVs are effectively decoupled from these extreme far-field input changes due to pupil centroid offsets, attesting to the effectiveness of the scrambler design. This experiment allows us to test the impact of these changes with large pupil variation on-sky, something we would not easily be able to do at a conventional optical telescope. While the pupil and illumination changes expected at these other telescopes are small, scaling from our results enables us to estimate and bound these effects, and show that they are controllable even for the new and next generation of RV instruments in their quest to beat down instrumental noise sources towards the goal of a few cm/s.

https://arxiv.org/abs/2103.05148

Source: https://phys.org/news/2021-12-evidence-coronal-cool-small-m-dwarf.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/20/2021 07:22 pm
Supermassive black hole at the center of our galaxy may have a friend

Quote
Finally, if there are two massive black holes orbiting each other at the galactic center, as my team suggests is possible, they will emit gravitational waves. Since 2015, the LIGO-Virgo observatories have been detecting gravitational wave radiation from merging stellar-mass black holes and neutron stars. These groundbreaking detections have opened a new way for scientists to sense the universe.

Any waves emitted by our hypothetical black hole pair will be at low frequencies, too low for the LIGO-Virgo detectors to sense. But a planned space-based detector known as LISA may be able to detect these waves which will help astrophysicists figure out whether our galactic center black hole is alone or has a partner.

https://newsroom.ucla.edu/stories/supermassive-black-hole-at-the-center-of-our-galaxy-may-have-a-friend
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 12/22/2021 04:07 pm
Rogue planets uncovered (ESOcast 249 Light):

https://youtu.be/fQNFj8GoZJA
Title: Re: Astronomy & Planetary Science Thread
Post by: jbenton on 12/27/2021 03:01 am
This came out a few days ago:

https://news.arizona.edu/story/astronomers-detect-signature-magnetic-field-exoplanet (https://news.arizona.edu/story/astronomers-detect-signature-magnetic-field-exoplanet)

Quote
An international team of astronomers used data from the Hubble Space Telescope to discover the signature of a magnetic field in a planet outside our solar system. The finding, described in a paper in the journal Nature Astronomy, marks the first time such a feature has been seen on an exoplanet.

A magnetic field best explains the observations of an extended region of charged carbon particles that surround the planet and stream away from it in a long tail. Magnetic fields play a crucial role in protecting planetary atmospheres, so the ability to detect the magnetic fields of exoplanets is a significant step toward better understanding what these alien worlds may look like.

The team used Hubble to observe the exoplanet HAT-P-11b, a Neptune-sized planet 123 light-years from Earth, pass directly across the face of its host star six times in what is known as a "transit." The observations were made in the ultraviolet light spectrum, which is just beyond what the human eye can see.

Hubble detected carbon ions – charged particles that interact with magnetic fields – surrounding the planet in what is known as a magnetosphere. A magnetosphere is a region around a celestial object (such as Earth) that is formed by the object's interaction with the solar wind emitted by its host star.

So I've read, becaues this transiting exoplanet orbits so close to its star, it is a frequent target for scientific observation. I've decided to link the Wikipedia article for it:
https://en.wikipedia.org/wiki/HAT-P-11b (https://en.wikipedia.org/wiki/HAT-P-11b)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/05/2022 10:04 am
Mysterious Dust-emitting Object Orbiting TIC 400799224

We report the discovery of a unique object of uncertain nature -- but quite possibly a disintegrating asteroid or minor planet -- orbiting one star of the widely separated binary TIC 400799224. We initially identified the system in data from TESS Sector 10 via an abnormally-shaped fading event in the light curve (hereafter 'dips'). Follow-up speckle imaging determined that TIC 400799224 is actually two stars of similar brightness at 0.62" separation, forming a likely bound binary with projected separation of ~300 au. We cannot yet determine which star in the binary is host to the dips in flux. ASAS-SN and Evryscope archival data show that there is a strong periodicity of the dips at ~19.77 days, leading us to believe that an occulting object is orbiting the host star, though the duration, depth, and shape of the dips vary substantially. Statistical analysis of the ASAS-SN data shows that the dips only occur sporadically at a detectable threshold in approximately one out of every three to five transits, lending credence to the possibility that the occulter is a sporadically-emitted dust cloud. The cloud is also fairly optically thick, blocking up to 37% or 75% of the light from the host star, depending on the true host. Further observations may allow for greater detail to be gleaned as to the origin and composition of the occulter, as well as to a determination of which of the two stars comprising TIC 400799224 is the true host star of the dips.

https://arxiv.org/abs/2110.01019
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/07/2022 08:08 pm
Star cluster ‘ruins’ discovered at Milky Way rim:

https://youtu.be/AHObdTl12Gg
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/07/2022 08:21 pm
The Worlds Biggest Telescopes Through History - From Galileo to Gran Telescopio Canarias:

https://youtu.be/JypEu99RXgY
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/11/2022 04:12 pm
Astronomers find ‘deformed’ planet that isn’t round for the first time

Quote
Astronomers have found a “deformed” exoplanet shaped like a rugby ball for the first time.

The planet has been stretched out and squashed down by the tidal forces between it and Wasp-103, the distant star around which it orbits. That star is about 200 degrees hotter and 1.7 times bigger than our Sun.

The unusual planet known as Wasp-103b was spotted using new data from Cheops, the European Space Agency’s mission to find exoplanets, which was combined with existing information from the Hubble and Spitzer space elescopes.

https://www.independent.co.uk/space/planet-round-shape-deformed-wasp-103b-b1990735.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/11/2022 07:03 pm
‘Small’ supermassive black hole discovery could answer growth questions:

https://youtu.be/VdBsG5sgHWs
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 01/13/2022 06:56 pm
Cool Worlds - We Discovered a New Exomoon Candidate! A Survey of 70 Cool Gas Giants:

https://youtu.be/Blej3YvveCI

An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i

Abstract
Exomoons represent a crucial missing puzzle piece in our efforts to understand extrasolar planetary systems. To address this deficiency, we here describe an exomoon survey of 70 cool, giant transiting exoplanet candidates found by Kepler. We identify only one exhibiting a moon-like signal that passes a battery of vetting tests: Kepler-1708 b. We show that Kepler-1708 b is a statistically validated Jupiter-sized planet orbiting a Sun-like quiescent star at 1.6 au. The signal of the exomoon candidate, Kepler-1708 b-i, is a 4.8σ effect and is persistent across different instrumental detrending methods, with a 1% false-positive probability via injection–recovery. Kepler-1708 b-i is ~2.6 Earth radii and is located in an approximately coplanar orbit at ~12 planetary radii from its ~1.6 au Jupiter-sized host. Future observations will be necessary to validate or reject the candidate.

https://www.nature.com/articles/s41550-021-01539-1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/13/2022 07:23 pm
It’s another sub-Neptune exomoon candidate around a cool gas giant.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/17/2022 04:45 pm
Citizen Scientists Spot Jupiter-like Planet in NASA TESS Data

Tom Jacobs of Bellevue, Washington, loves treasure hunts. Since 2010, the former U.S. naval officer has participated in online volunteer projects that allow anyone who is interested — “citizen scientists” — to look through NASA telescope data for signs of exoplanets, planets beyond our solar system.

Now, Jacobs has helped discover a giant gaseous planet about 379 light-years from Earth, orbiting a star with the same mass as the Sun. The Jupiter-size planet is special for astronomers because its 261-day year is long compared to many known gas giants outside our solar system. The result also suggests the planet is just a bit farther from its star than Venus is from the Sun. The finding was published in the Astronomical Journal and presented at an American Astronomical Society virtual press event on Jan. 13.

Uncovering this planet and pinning down its size and mass required a large collaboration between professional astronomers and citizen scientists like Jacobs. To track the planet, they engaged in “a global uniting effort, because we all need to go after it together to keep eyes on this particular planet,” said Paul Dalba, astronomer at the University of California, Riverside, and lead author of the study.

“Discovering and publishing TOI-2180 b was a great group effort demonstrating that professional astronomers and seasoned citizen scientists can successfully work together,” Jacobs said. “It is synergy at its best.”

How the discovery happened

The signature for the newly discovered planet was hiding in data from NASA’s Transiting Exoplanet Survey Satellite, or TESS. Using TESS data, scientists look for changes in brightness of nearby stars, which could indicate the presence of orbiting planets.

Jacobs is part of a group of citizen scientists who look at plots of TESS data, showing the change in a star’s brightness over time, in search of new planets. While professional astronomers use algorithms to scan tens of thousands of data points from stars automatically, these citizen scientists use a program called LcTools, created by Alan R. Schmitt, to inspect telescope data by eye. That’s why Jacobs’ group, which includes several citizen scientists and two veteran astronomers, calls themselves the Visual Survey Group. Many of them met while working on Planet Hunters, a NASA-funded citizen science project through Zooniverse that focused on data from NASA’s Kepler spacecraft.

On February 1, 2020, Jacobs happened to notice a plot showing starlight from TOI-2180 dim by less than half a percent and then return to its previous brightness level over a 24-hour period, which may be explained by an orbiting planet that is said to “transit” as it passes in front of the star from our point of view. By measuring the amount of light that dims as the planet passes, scientists can estimate how big the planet is and, in combination with other measurements, its density. But a transit can only be seen if a star and its planet line up with telescopes looking for them.

A graph showing starlight over time is called a “light curve.” The Visual Survey Group alerted two professional scientist collaborators — Paul Dalba at the University of California, Riverside, and Diana Dragomir, assistant professor at the University of New Mexico, that this light curve was potentially interesting.

“With this new discovery, we are also pushing the limits of the kinds of planets we can extract from TESS observations,” Dragomir said. “TESS was not specifically designed to find such long-orbit exoplanets, but our team, with the help of citizen scientists, are digging out these rare gems nonetheless.”

Computer algorithms used by professional astronomers are designed to search for planets by identifying multiple transit events from a single star. That’s why citizen scientists’ visual inspection is so useful when there is only one transit available. Since this is the only instance of the TOI-2180 b star dimming in this dataset, it is called a “single transit event.”

“The manual effort that they put in is really important and really impressive, because it's actually hard to write code that can go through a million light curves and identify single transit events reliably,” Dalba said. “This is one area where humans are still beating code.”

But how could the team rule out other explanations for the brief dip in starlight? Could they be sure they had found a planet? They would need follow-up observations.

Fortunately, Dalba was able to recruit the Automated Planet Finder Telescope at Lick Observatory in California. “I use that telescope to measure the wobble of the star to then determine how massive this planet is, if it is a planet at all,” he said. The research team also used the Keck I telescope at the W. M. Keck Observatory in Hawaii to perform some of these measurements when Lick Observatory was threatened by wildfires.

With 27 hours of observations spread over more than 500 days, Dalba and colleagues observed the planet’s gravitational tug on the star, which allowed them to calculate the planet’s mass and estimate a range of possibilities for its orbit. Still, they wanted to observe the planet’s transit when it came back around to confirm the orbit. Unfortunately, finding a second transit event was going to be difficult because there was so much uncertainty about when the planet would cross the face of its star again.

Dalba pressed on, and organized an observing campaign including both professional astronomers and citizen scientists using telescopes at 14 sites across three continents in August 2020. To support the campaign, Dalba camped for five nights in California’s Joshua Tree National Park and looked for the transit with two portable amateur telescopes. The collaborative effort yielded 55 datasets over 11 days.

Ultimately, none of these telescopes detected the planet with confidence. Still, the lack of a clear detection in this time period put a boundary on how long the orbit could be, indicating a period of about 261 days. Using that estimate, they predict TESS will see the planet transit its star again in February 2022.

About the planet

TOI-2180 b is almost three times more massive than Jupiter but has the same diameter, meaning it is more dense than Jupiter. This made scientists wonder whether it formed in a different way than Jupiter.

Another clue about the planet’s formation could be what’s inside it. Through computer models they determined that the new planet may have as much as 105 Earth masses worth of elements heavier than hydrogen and helium. “That’s a lot,” says Dalba. “That’s more than what we suspect is inside Jupiter.”

Astronomers still have much to learn about the range of planets that are out there. About 4,800 exoplanets have been confirmed, but there are thought to be billions of planets in our galaxy. The new finding indicates that among giant planets, some have many more heavy elements than others.

In our solar system, gigantic Jupiter orbits the Sun every 12 years; for Saturn, a “year” is 29 years. We don’t have giant planets like TOI-2180 b between the Earth and Sun. But outside the solar system, astronomers have found dozens of exoplanets that are even bigger than Jupiter and orbit much closer to their stars, even closer than the orbit of Mercury.

With an average temperature of about 170 degrees Fahrenheit, TOI-2180 b is warmer than room temperature on Earth, and warmer than the outer planets of our solar system including Jupiter and Saturn. But compared to the array of transiting giant exoplanets that astronomers have found orbiting other stars, TOI-2180 b is abnormally chilly.

“It's a nice stepping stone in between most giant exoplanets we’ve found, and then really cold Jupiter and Saturn,” Dalba said.

What’s next

When TESS observes the star again in February, Dalba and the citizen scientists are eager to get the data and dive back in. If they find the planet’s signature, confirming the 261-day period, that would give more meaning to the data from their global campaign to find it in 2020.

NASA’s James Webb Space Telescope, which launched on Dec. 25, could potentially observe this planet and its atmosphere. But there’s another reason Dalba is excited about Webb’s capabilities. Given that in our own solar system, Jupiter has rings and moons, Webb could be used to look for the presence of small objects orbiting TOI-2180 b.

So far, no rings or moons have been found outside of our solar system with certainty, but one reason could be that many exoplanets are found very close to their star, whose gravity might strip such objects away. TOI-2180 b, located at a farther distance from its host star, might present an interesting opportunity for such a search. “I think this is a fun system for that later on in the future,” Dalba said.

When he’s not pursuing his planet-hunting hobby, Jacobs, the citizen scientist, works with nonprofits that help people with disabilities find employment in their communities.

The Visual Survey Group members “devote many hours each day surveying the data out of pure joy and interest in furthering science,” said Jacobs. Collectively, the team has co-authored more than 68 peer-reviewed science papers, including the discovery of transiting “exocomets” or comets outside the solar system crossing the face of a star.

“We love contributing to science,” Jacobs said. “And I love this type of surveying, knowing that one is in new undiscovered territory not seen by any humans before.”

More About Citizen Science

NASA has a wide variety of citizen science collaborations across topics ranging from Earth science to the Sun to the wider universe. Anyone in the world can participate. Check out the latest opportunities at science.nasa.gov/citizenscience.

About TESS

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Center for Astrophysics | Harvard &amp; Smithsonian in Cambridge, Massachusetts; MIT’s Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

The National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship Program contributed support to this study.

By Elizabeth Landau
NASA Headquarters
[email protected]

https://www.nasa.gov/feature/citizen-scientists-spot-jupiter-like-planet-in-nasa-tess-data
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/26/2022 04:24 pm
Quote
The supermassive black hole lurking at the heart of the Milky Way – Sagittarius A*, or Sgr A* for short – contains about 4.3 million solar masses, and, as it turns out, nearly all of the mass at the very center of the galaxy.

An international team of astronomers, using the Gemini North telescope in Hawaii and the European Southern Observatory’s Very Large Telescope, measured the position and velocity of four stars in the immediate neighbourhood of Sgr A* and found them to be moving in the manner one would expect if the black hole accounted for 99.9 percent of the matter at the center of the Milky Way.

https://astronomynow.com/2022/01/17/black-hole-contains-nearly-all-the-mass-at-the-heart-of-the-milky-way/

https://youtu.be/XanbXkQCg6I
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 01/26/2022 04:52 pm
Quote
Something in Earth's cosmic neighborhood is emitting weird signals of a kind we've never seen before.
Just 4,000 light-years away, something is flashing radio waves. For roughly 30 to 60 seconds, every 18.18 minutes, it pulses brightly, one of the most luminous objects in the low-frequency radio sky. It matches the profile of no known astronomical object, and astronomers are gobsmacked. They have named it GLEAM-X J162759.5-523504.3.

Quote
”This object was appearing and disappearing over a few hours during our observations," said astrophysicist Natasha Hurley-Walker of the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Australia.
"That was completely unexpected. It was kind of spooky for an astronomer because there's nothing known in the sky that does that. And it's really quite close to us – about 4,000 light-years away. It's in our galactic backyard."
At the moment, they believe it is most likely one of two things, both 'dead' stars: a type of ultra-magnetic neutron star called a magnetar, or, with a smaller likelihood, a highly magnetized white dwarf. If it's the former, it would be the first time we've detected a magnetar with a very long pulsation period, known as an ultra-long period magnetar.

https://www.sciencealert.com/something-in-our-cosmic-vicinity-is-spitting-out-strange-signals-we-ve-never-seen-before/amp

A radio transient with unusually slow periodic emission

Abstract
The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has, so far, been quiet beyond the Galactic pulsar population and the long-term scintillation of active galactic nuclei. The low-frequency band, however, is sensitive to exotic coherent and polarized radio-emission processes, such as electron-cyclotron maser emission from flaring M dwarfs1, stellar magnetospheric plasma interactions with exoplanets2 and a population of steep-spectrum pulsars3, making Galactic-plane searches a prospect for blind-transient discovery. Here we report an analysis of archival low-frequency radio data that reveals a periodic, low-frequency radio transient. We find that the source pulses every 18.18 min, an unusual periodicity that has, to our knowledge, not been observed previously. The emission is highly linearly polarized, bright, persists for 30–60 s on each occurrence and is visible across a broad frequency range. At times, the pulses comprise short-duration (&lt;0.5 s) bursts; at others, a smoother profile is observed. These profiles evolve on timescales of hours. By measuring the dispersion of the radio pulses with respect to frequency, we have localized the source to within our own Galaxy and suggest that it could be an ultra-long-period magnetar.

https://www.nature.com/articles/s41586-021-04272-x
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/31/2022 04:50 pm
Crater Tree Rings

This feature could easily be mistaken for a tree stump with characteristic concentric rings. It’s actually an impressive birds-eye view into an ice-rich impact crater on Mars. Tree rings provide snapshots of Earth’s past climate and, although formed in a very different way, the patterns inside this crater reveal details of the Red Planet’s history, too.

The image was taken by the CaSSIS camera onboard the ESA/Roscosmos ExoMars Trace Gas Orbiter (TGO) on 13 June 2021 in the vast northern plains of Acidalia Planitia, centred at 51.9°N/326.7°E.

The interior of the crater is filled with deposits that are probably water-ice rich. It is thought that these deposits were laid down during an earlier time in Mars’ history when the inclination of the planet’s spin axis allowed water-ice deposits to form at lower latitudes than it does today. Just like on Earth, Mars’ tilt gives rises to seasons, but unlike Earth its tilt has changed dramatically over long periods of time.

One of the notable features in the crater deposits is the presence of quasi-circular and polygonal patterns of fractures. These features are likely a result of seasonal changes in temperature that cause cycles of expansion and contraction of the ice-rich material, eventually leading to the development of fractures.

Understanding the history of water on Mars and if this once allowed life to flourish is at the heart of ESA’s ExoMars missions. TGO arrived at Mars in 2016 and began its full science mission in 2018. The spacecraft is not only returning spectacular images, but also providing the best ever inventory of the planet’s atmospheric gases with a particular emphasis on geologically and biologically important gases, and mapping the planet’s surface for water-rich locations. It will also provide data relay services for the second ExoMars mission comprising the Rosalind Franklin rover and Kazachok platform, when it arrives on Mars in 2023. The rover will explore a region of Mars thought once to have hosted an ancient ocean, and will search underground for signs of life.

https://www.esa.int/ESA_Multimedia/Images/2022/01/Crater_tree_rings
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/01/2022 04:53 pm
2nd Earth trojan asteroid confirmed! Much bigger than first!

https://youtu.be/Sh-XtwVbvOo
Title: Re: Astronomy & Planetary Science Thread
Post by: launchwatcher on 02/02/2022 02:44 pm
2nd Earth trojan asteroid confirmed! Much bigger than first!

Designated 2020 XL5.   Discovered using Pan-STARRS 1 survey telescope.   1.2km diameter.

News coverage here:

https://www.space.com/earth-extra-moon-trojan-asteroid-2020-xl5-discovery

https://www.nytimes.com/2022/02/02/science/astronomy-asteroid-trojan.html


Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/06/2022 02:28 pm
Habitable Exomoons? Interview with David Kipping of Cool Worlds:

https://youtu.be/-pTr2hvfsWo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/09/2022 01:48 pm
Quote
Last year in August, a surprise tsunami in the South Atlantic Ocean mushroomed to distances over 10,000 kilometers (more than 6,000 miles) away, rippling through the North Atlantic, the Pacific, and the Indian Oceans.

Quote
As it turns out, however, this tsunami wasn't just the product of a single 7.5-magnitude earthquake. A fresh look at the seismological data suggests it was actually a series of five sub-quakes, and in their midst, was hiding a much larger and shallower rumble that was probably what set loose the global tsunami.
This 'invisible' third quake struck just 15 kilometers below the Earth's surface at a magnitude of 8.2. Yet in the crowd of quakes, our monitoring systems completely missed it.

https://www.sciencealert.com/we-just-figured-out-how-a-global-spreading-tsunami-in-2021-took-us-by-complete-surprise/amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/10/2022 10:56 am
Scientists unveil 'most accurate' virtual representation of universe, backing Cold Dark Matter model

Quote
The simulations, which were unveiled at Durham university, show how our part of the universe evolved from the Big Bang to the present and provide proof that the current theories to explain the forces that shape the cosmos are on the right lines.

https://news.sky.com/story/amp/scientists-unveil-most-accurate-virtual-representation-of-universe-12537803
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/10/2022 01:06 pm
Ultralight Planet Found Next Door (ESOcast 250 Light)

https://youtu.be/6FXRdIZ8W6s

This is Proxima d.

https://amp.theguardian.com/science/2022/feb/10/scientists-discover-new-planet-orbiting-nearest-star-to-solar-system
Title: Re: Astronomy & Planetary Science Thread
Post by: Robotbeat on 02/10/2022 02:14 pm
Looks like it orbits about 0.029AU from Proxima Centauri, which is 0.0017 times as bright as the Sun, so it should get pretty close to exactly twice the insolation of the Earth, very close to the same insolation as Venus. But it’s smaller, so it probably has less atmosphere and therefore may be relatively close to Earthlike temperatures but with big temperature swings. If it’s tidally locked, maybe it’d be habitable-ish near the terminator. Depends super strongly on the atmosphere.

Proxima Centauri is starting to look like a pretty interesting little stellar system with more than one potentially-almost-habitable worlds to explore. Shame about the stellar flares. But hope springs eternal!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/10/2022 03:34 pm
I am guessing there is nothing to rule out planets orbiting further out beyond Proxima C.
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 02/10/2022 04:06 pm
Looks like it orbits about 0.029AU from Proxima Centauri, which is 0.0017 times as bright as the Sun, so it should get pretty close to exactly twice the insolation of the Earth, very close to the same insolation as Venus. But it’s smaller, so it probably has less atmosphere and therefore may be relatively close to Earthlike temperatures but with big temperature swings. If it’s tidally locked, maybe it’d be habitable-ish near the terminator. Depends super strongly on the atmosphere.

Proxima Centauri is starting to look like a pretty interesting little stellar system with more than one potentially-almost-habitable worlds to explore. Shame about the stellar flares. But hope springs eternal!
The trouble is atmospheric models for exo planets have such crazy margins of error that the result can basically say anything the author wants. Earth paradise and venus hellscape can both be in the margins of error.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/11/2022 10:28 am
Life could exist on planet orbiting 'white dwarf' star

Quote
The planet was detected in the star's "habitable zone", where it's neither too cold nor too hot to sustain life.

https://www.bbc.co.uk/news/science-environment-60325010
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/15/2022 09:09 pm
Quote
A trans-neptunian object has been discovered using the Vatican Advanced Technology Telescope!

The object was discovered on Dec. 3, 2021 – Jesuit Richard Boyle made the first observations, and analysis was done by Lithuanian astronomer and astrophysicist Kazimieras Černis.

Peter Veres of the IAU’s Minor Planet Center calculated the object’s orbit using these and subsequent observations by Boyle; Peter also happens to be an alumnus of the 2007 Vatican Observatory Summer School!

The object has an orbital period of 286.98 years, with a perihelion of 35.26 AU, and an aphelion of 51.76 AU; as of this writing, it is 35.27 AU from the Sun – very close to perihelion.

https://www.vaticanobservatory.org/sacred-space-astronomy/tno-2021-xd7/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/16/2022 08:15 am
Secondary cratering on Earth: The Wyoming impact crater field

https://pubs.geoscienceworld.org/gsa/gsabulletin/article/doi/10.1130/B36196.1/611743/Secondary-cratering-on-Earth-The-Wyoming-impact
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/16/2022 05:10 pm
Uncovering a Black Hole in an Immense Dust Cloud (ESOcast 251 Light)

https://youtu.be/TIyp2IwQvDs
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/19/2022 02:04 pm
Earth’s inner core: a mixture of solid Fe and liquid-like light elements

Quote
A joint research team led by Prof. HE Yu the Institute of Geochemistry of the Chinese Academy of Sciences (IGCAS) has found that the inner core of the Earth is not a normal solid but is composed of a solid iron sublattice and liquid-like light elements, which is also known as a superionic state. The liquid-like light elements are highly diffusive in iron sublattices under inner core conditions.

This study was published in Nature on Feb. 9.

A superionic state, which is an intermediate state between solid and liquid, widely exists in the interior of planets. Using high-pressure and high-temperature computational simulations based on quantum mechanics theory, researchers from IGCAS and the Center for High Pressure Science & Technology Advanced Research (HPSTAR) found that some Fe-H, Fe-C and Fe-O alloys transformed into a superionic state under inner core conditions.

In superionic iron alloys, light elements become disordered and diffuse like a liquid in the lattice, while iron atoms remain ordered and vibrate about their lattice grid, forming the solid iron framework. The diffusion coefficients of C, H and O in superionic iron alloys are the same as those in liquid Fe.

"It is quite abnormal. The solidification of iron at the inner core boundary does not change the mobility of these light elements, and the convection of light elements is continuous in the inner core," said Prof. HE Yu, the first and corresponding author of the study.

https://www.eurekalert.org/news-releases/942527
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/22/2022 08:41 am
Quote
Space agency NASA has announced that the number of known exoplanets—planets that orbit a star other than our Sun—has passed the 5,000 mark.

The latest batch, a haul of 65 “new” exoplanets that includes a red dwarf star with five orbiting planets, has been added to the NASA Exoplanet Archive.

However, scientists at the Massachusetts Institute of Technology (MIT) has discovered that three—and possibly four—of the exoplanets included in the archive are, in fact, just stars.

Quote
However, there are doubts even about some confirmed exoplanets. A new paper published in the Astronomical Journal contains evidence against the very existence of four exoplanets.

Originally discovered by NASA’s Kepler Space Telescope—a missions from 2009 through 2018 that’s responsible for the lion’s share of exoplanet detections—it’s claimed that four exoplanets have been misclassified.

The authors estimate Kepler-854b, Kepler-840b and Kepler-699b to be between two and four times the size of Jupiter. They used new data on the measurements of planets from the new Gaia mission, which has been precisely measuring and mapping the properties and movements of stars in the Milky Way.

In short, they’re stars, not planets.

Quote
Could there be more rogue stars masquerading as planets in NASA’s Exoplanet Archive? probably not. “This is a tiny correction [that] comes from the better understanding of stars, which is only improving all the time,” said Shporer. “These misclassifications are not going to happen many times more.”

https://www.forbes.com/sites/jamiecartereurope/2022/03/21/four-of-our-planets-are-missing-nasa-announces-5000th-new-alien-world-but-some-are-imposters-say-scientists/

https://youtu.be/2qDg5uHk-4c
Title: Re: Astronomy & Planetary Science Thread
Post by: su27k on 03/25/2022 02:58 am
Astronomy's contribution to climate change rivals the emissions from some countries (https://www.npr.org/2022/03/21/1087203642/astronomys-contribution-to-climate-change-rivals-the-emissions-from-some-countri)

Quote from: NPR
Astronomers spend their careers looking up at the sky, away from Earth, but now some stargazers say their field has to grapple with the fact that observing the cosmos is contributing to their home planet's climate emergency.

A new estimate of the greenhouse gas emissions linked to all ground- and space-based telescopes, in the journal Nature Astronomy, says the annual carbon footprint of astronomy's research infrastructure is equivalent to about 20 million metric tons of carbon dioxide.

"Just to give you some perspective — 20 million tonnes of CO2 — this is the annual carbon footprint of countries like Estonia, Croatia, or Bulgaria," says Jürgen Knödlseder, an astronomer at IRAP, an astrophysics laboratory in France.


The paper: Estimate of the carbon footprint of astronomical research infrastructures (https://arxiv.org/abs/2201.08748)
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 03/25/2022 01:48 pm
Astronomy's contribution to climate change rivals the emissions from some countries (https://www.npr.org/2022/03/21/1087203642/astronomys-contribution-to-climate-change-rivals-the-emissions-from-some-countri)

Quote from: NPR
Astronomers spend their careers looking up at the sky, away from Earth, but now some stargazers say their field has to grapple with the fact that observing the cosmos is contributing to their home planet's climate emergency.

A new estimate of the greenhouse gas emissions linked to all ground- and space-based telescopes, in the journal Nature Astronomy, says the annual carbon footprint of astronomy's research infrastructure is equivalent to about 20 million metric tons of carbon dioxide.

"Just to give you some perspective — 20 million tonnes of CO2 — this is the annual carbon footprint of countries like Estonia, Croatia, or Bulgaria," says Jürgen Knödlseder, an astronomer at IRAP, an astrophysics laboratory in France.

I've seen things about this too, and its a connundrum. Astronomers feel its tricky for them to talk about climate change when their profession is a big emitter. Astronomy emissions come from 2 big areas:

1. Travel - lots of flying around the world to conferences and such. Silver lining of the pandemic is it forced them to consider remote conference attendance.

2. Computing - lots of super computer usage. These things are really power thirsty and are totally essential for data crunching and modeling
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/09/2022 02:10 pm
LADUMA: Discovery of a luminous OH megamaser at z>0.5

In the local Universe, OH megamasers (OHMs) are detected almost exclusively in infrared-luminous galaxies, with a prevalence that increases with IR luminosity, suggesting that they trace gas-rich galaxy mergers. Given the proximity of the rest frequencies of OH and the hyperfine transition of neutral atomic hydrogen (HI), radio surveys to probe the cosmic evolution of HI in galaxies also offer exciting prospects for exploiting OHMs to probe the cosmic history of gas-rich mergers. Using observations for the Looking At the Distant Universe with the MeerKAT Array (LADUMA) deep HI survey, we report the first untargeted detection of an OHM at z>0.5, LADUMA J033046.20−275518.1 (nicknamed "Nkalakatha"). The host system, WISEA J033046.26−275518.3, is an infrared-luminous radio galaxy whose optical redshift z≈0.52 confirms the MeerKAT emission line detection as OH at a redshift zOH=0.5225±0.0001 rather than HI at lower redshift. The detected spectral line has 18.4σ peak significance, a width of 459±59kms−1, and an integrated luminosity of (6.31±0.18[statistical]±0.31[systematic])×103L⊙, placing it among the most luminous OHMs known. The galaxy's far-infrared luminosity LFIR=(1.576±0.013)×1012L⊙ marks it as an ultra-luminous infrared galaxy; its ratio of OH and infrared luminosities is similar to those for lower-redshift OHMs. A comparison between optical and OH redshifts offers a slight indication of an OH outflow. This detection represents the first step towards a systematic exploitation of OHMs as a tracer of galaxy growth at high redshifts.

https://arxiv.org/abs/2204.02523

Quote
Using the MeerKAT radio telescope, a team of researchers from the University of the Western Cape, the University of Cape Town, Rhodes University, the South African Radio Astronomy Observatory and the South African Astronomical Observatory together with colleagues from twelve other countries have discovered a powerful megamaser – a radio-wavelength laser indicative of colliding galaxies. This is the most distant such megamaser found so far.

https://astro.uwc.ac.za/megamaser-nkalakatha-discovered-by-astronomers-using-meerkat/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/11/2022 06:57 am
Space Force is Releasing Decades of Tracking Data on a Thousand Bright Meteor Fireballs

https://www.universetoday.com/155380/space-force-is-releasing-decades-of-tracking-data-on-a-thousand-bright-meteor-fireballs/
Title: Re: Astronomy & Planetary Science Thread
Post by: JaffH_iii on 04/11/2022 07:53 am
Space Force is Releasing Decades of Tracking Data on a Thousand Bright Meteor Fireballs

https://www.universetoday.com/155380/space-force-is-releasing-decades-of-tracking-data-on-a-thousand-bright-meteor-fireballs/
Thanks for sharing  ;)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/11/2022 02:15 pm
U.S. Space Force Releases Decades of Bolide Data to NASA for Planetary Defense Studies

An agreement between NASA and the U.S. Space Force recently authorized the public release of decades of data collected by U.S. government sensors on fireball events (large bright meteors also known as bolides) for the benefit of the scientific and planetary defense communities. This action results from collaboration between NASA’s Planetary Defense Coordination Office (PDCO) and the U.S. Space Force to continue furthering our nation’s efforts in planetary defense, which include finding, tracking, characterizing, and cataloguing near-Earth objects (NEOs). The newly released data is comprised of information on the changing brightness of bolides as they pass through Earth’s atmosphere, called light curves, that could enhance the planetary defense community’s current ability to model the effects of impacts by larger asteroids that could one day pose a threat to Earth.

Bolides, very bright meteors that can even be seen in daylight, are a regular occurrence – on the order of several dozen times per year – that result when our planet is impacted by asteroids too small to reach the ground but large enough to explode upon impact with Earth’s atmosphere. U.S. government sensors detect these atmospheric impact events, and the bolide data is reported to the NASA Jet Propulsion Laboratory’s Center for Near Earth Object Studies (CNEOS) fireballs database, which contains data going back to 1988 for nearly one thousand bolide events. Now, planetary defense experts will have access to even more detailed data – specifically, light curve information that captures the optical intensity variation during the several seconds of an object’s breakup in the atmosphere. The data will be available to scientists as soon as it is properly archived, with the reported events and made easily accessible. This uniquely rich data set has been greatly sought after by the scientific community as an object’s breakup in Earth’s atmosphere provides scientific insight into the object’s strength and composition based on what altitudes at which it breaks up and disintegrates. The approximate total radiated energy and pre-entry velocity vector (i.e., direction) can also be better derived from bolide light curve data.

“The growing archive of bolide reports, as posted on the NASA CNEOS Fireballs website, has significantly increased scientific knowledge and contributes to the White House approved National Near-Earth Object Preparedness Strategy and Action Plan” said Lindley Johnson, planetary defense officer at NASA Headquarters. “The release of these new bolide data demonstrates another key area of collaboration between NASA and the U.S. Space Force and helps further the pursuit of improved capabilities for understanding these objects and our preparedness to respond to the impact hazard NEOs pose to Earth.” 

Recently a small asteroid approximately 2 meters in size, so small it posed no hazard to Earth, was detected in space as it approached Earth and impacted the atmosphere southwest of Jan Mayen, a Norwegian island nearly 300 miles (470 kilometers) off the east coast of Greenland and northeast of Iceland. While this asteroid, designated 2022 EB5, was much smaller than objects NASA is tasked to detect and warn about, CNEOS continued to update NASA’s PDCO with impact location predictions as observations were collected leading up to 2022 EB5’s impact, offering the planetary defense community a real-word scenario to test NEO tracking capabilities and give confidence that the impact prediction process and models are adequate for timely and accurate notification of the potential impact of a larger object, should one be discovered on a trajectory toward Earth. Like other bolide events, 2022 EB5’s impact was detected by U.S. Government sensors and reported by the U.S. Space Force units, confirming the time and location predicted by CNEOS, and added to NASA's archive of these events at JPL CNEOS.

Another notable bolide event in this released data set is of a meteor that was detected on Jan 8, 2014. This object gained the interest of the scientific community as it has been posited it could have interstellar origin due to the detected event’s high velocity within the atmosphere. Further analysis carried out under U.S. Space Command’s purview confirmed the object’s high velocity impact, but the short duration of collected data, less than five seconds, makes it difficult to definitively determine if the object’s origin was indeed interstellar.

NASA established the PDCO in 2016 to manage the agency’s ongoing efforts in planetary defense. NASA has been directed to discover 90% of NEOs larger than 140 meters (459 feet) in size. The agency is diligently working to achieve this directive and has currently found approximately 40% of near-Earth asteroids larger than that size.

For more information about PDCO, visit:

https://www.nasa.gov/planetarydefense

Follow NASA Asteroid Watch on Twitter at @AsteroidWatch.

Josh Handal / Karen Fox
Headquarters, Washington
202-358-1600 / 301-286-6284
[email protected] / [email protected]

https://www.nasa.gov/feature/us-space-force-releases-decades-of-bolide-data-to-nasa-for-planetary-defense-studies
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/11/2022 04:18 pm
What’s Happening To Neptune? Massive Telescopes See Something Weird Going On With The Eighth Planet

Quote
Something unexpected is happening on Neptune and astronomers aren’t sure why.

Using a fleet of ground-based telescopes—including the massive Very Large Telescope in Chile—an international team of astronomers have seem some dramatic temperature changes on the eight planet from the Sun.

It’s now become clear that over the last 17 years there’s been a surprising drop in Neptune’s global temperatures followed by a dramatic warming at its south pole. The findings are published today in The Planetary Science Journal.

“This change was unexpected,” said Michael Roman, a postdoctoral research associate at the University of Leicester in the U.K and lead author of the study. “Since we have been observing Neptune during its early southern summer, we expected temperatures to be slowly growing warmer, not colder.”

Seasons are long on Neptune. The “ice giant” orbits the Sun once every 165 -Earth years, so variations on long timescales are expected roughly every 40 years.

https://www.forbes.com/sites/jamiecartereurope/2022/04/11/whats-happening-to-neptune-massive-telescope-sees-something-weird-going-on-with-the-eighth-planet/

Evolution of thermal images from Neptune:

https://youtu.be/gMzz1Fs83EU
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/20/2022 04:21 pm
Micronovae - a New Kind of Stellar Explosion (ESOcast 254 Light)

https://youtu.be/XouB5QYnAVM
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/23/2022 04:54 pm
Large Hadron Collider restarts

Beams of protons are again circulating around the collider’s 27-kilometre ring, marking the end of a multiple-year hiatus for upgrade work

22 APRIL, 2022

The world’s largest and most powerful particle accelerator has restarted after a break of more than three years for maintenance, consolidation and upgrade work. Today, 22 April, at 12:16 CEST, two beams of protons circulated in opposite directions around the Large Hadron Collider’s 27-kilometre ring at their injection energy of 450 billion electronvolts (450 GeV).

“These beams circulated at injection energy and contained a relatively small number of protons. High-intensity, high-energy collisions are a couple of months away,” says the Head of CERN’s Beams department, Rhodri Jones. “But first beams represent the successful restart of the accelerator after all the hard work of the long shutdown.”

“The machines and facilities underwent major upgrades during the second long shutdown of CERN’s accelerator complex,” says CERN’s Director for Accelerators and Technology, Mike Lamont. “The LHC itself has undergone an extensive consolidation programme and will now operate at an even higher energy and, thanks to major improvements in the injector complex, it will deliver significantly more data to the upgraded LHC experiments.”

Pilot beams circulated in the LHC for a brief period in October 2021. However, the beams that circulated today mark not only the end of the second long shutdown for the LHC but also the beginning of preparations for four years of physics-data taking, which is expected to start this summer.

Until then, LHC experts will work around the clock to progressively recommission the machine and safely ramp up the energy and intensity of the beams before delivering collisions to the experiments at a record energy of 13.6 trillion electronvolts (13.6 TeV).

This third run of the LHC, called Run 3, will see the machine’s experiments collecting data from collisions not only at a record energy but also in unparalleled numbers. The ATLAS and CMS experiments can each expect to receive more collisions during this physics run than in the two previous physics runs combined, while LHCb, which underwent a complete revamp during the shutdown, can hope to see its collision count increase by a factor of three. Meanwhile, ALICE, a specialised detector for studying heavy-ion collisions, can expect a fifty times increase in the total number of recorded ion collisions, thanks to the recent completion of a major upgrade.

The unprecedented number of collisions will allow international teams of physicists at CERN and across the world to study the Higgs boson in great detail and put the Standard Model of particle physics and its various extensions to the most stringent tests yet.

Other things to look forward to in Run 3 include the operation of two new experiments, FASER and SND@LHC, designed to look for physics beyond the Standard Model; special proton–helium collisions to measure how often the antimatter counterparts of protons are produced in these collisions; and collisions involving oxygen ions that will improve physicists’ knowledge of cosmic-ray physics and the quark–gluon plasma, a state of matter that existed shortly after the Big Bang.

Videos:

VNR: https://videos.cern.ch/record/2295778

The LS2 upgrades to the LHC detectors: https://videos.cern.ch/record/2295775

The LS2 upgrades to the CERN accelerators chain: https://videos.cern.ch/record/2295776

The LHC and the accelerator complex: here

Photos:

Photos of the restart: https://cds.cern.ch/record/2807018

The accelerator complex: https://home.cern/resources/image/accelerators/accelerator-complex-images-gallery

The LHC: https://home.cern/resources/image/accelerators/lhc-images-gallery

Media kit:

https://home.cern/press/2022
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/25/2022 06:38 am
Quote
WASHINGTON — A handful of ancient zircon crystals found in South Africa hold the oldest evidence of subduction, a key element of plate tectonics, according to a new study published today in AGU Advances, AGU’s journal for high-impact, open-access research and commentary across the Earth and space sciences.

These rare time capsules from Earth’s youth point to a transition around 3.8 billion years ago from a long-lived, stable rock surface to the active processes that shape our planet today, providing a new clue in a hot debate about when plate tectonics was set in motion.

https://news.agu.org/press-release/earliest-geochemical-evidence-of-plate-tectonics-found-in-3-8-billion-year-old-crystal/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/25/2022 02:38 pm
Resolved imaging of exoplanets with the solar gravitational lens

We discuss the feasibility of direct multipixel imaging of exoplanets with the solar gravitational lens (SGL) in the context of a realistic deep space mission. For this, we consider an optical telescope, placed in the image plane that forms in the strong interference region of the SGL. We consider an Earth-like exoplanet located in our immediate stellar neighborhood and model its characteristics using our own Earth. We estimate photon fluxes from such a compact, extended, resolved exoplanet. This light appears in the form of an Einstein ring around the Sun, seen through the solar corona. The solar corona background contributes a significant amount of stochastic noise and represents the main noise source for observations utilizing the SGL. We estimate the magnitude of this noise. We compute the resulting signal-no-noise ratios and related integration times that are needed to perform imaging measurements under realistic conditions. We conclude that an imaging mission is challenging but feasible, using technologies that are either already available or in active development. Under realistic conditions, megapixel imaging of Earth-like exoplanets in our galactic neighborhood requires only weeks or months of integration time, not years as previously thought.

https://arxiv.org/abs/2204.04866
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/29/2022 08:40 am
I am guessing this will be an image of Sagittarius A*.

Media Advisory 22-001
Event Horizon Telescope Collaboration to announce groundbreaking results about the center of our galaxy

April 28, 2022

The U.S. National Science Foundation with the Event Horizon Telescope Collaboration will hold a press conference to announce a groundbreaking discovery in the Milky Way.

LOCATION – The National Press Club, 529 14th St N.W., Washington, D.C., 20045. The event will also be streamed live online.

Who: NSF's Chief Operating Officer Karen Marrongelle will deliver opening remarks. A panel of Event Horizon Telescope, or EHT, researchers will present their findings and answer questions from the media:

Katherine (Katie) L. Bouman, Assistant Professor of Computing and Mathematical Sciences, Electrical Engineering and Astronomy at Caltech
Vincent Fish, Research Scientist at MIT Haystack Observatory
Feryal Özel, Professor, Departments of Astronomy and Physics at University of Arizona
Michael Johnson, Astrophysicist at Center for Astrophysics | Harvard &amp; Smithsonian
What: Press conference on groundbreaking result from the Event Horizon Telescope.

When: Thursday, May 12, 2022, 9 a.m. EDT.

Where: The National Press Club, 529 14th St N.W., Washington, D.C., 20045. The event will also be streamed live online at https://nsf.gov/blackholes and on NSF's Facebook page at  https://www.facebook.com/US.NSF.

RSVP: Credentialed press can register to attend the event in person by contacting [email protected]. Please provide name of individual asking to attend, their title and the name of the outlet being represented. You will receive a confirmation email if your registration is accepted. The deadline to register is 6:00 p.m. EDT on Monday, May 9. Details about submitting questions or scheduling interviews will be sent to journalists with the registration confirmation NLT May 11.

Immediately following the press conference, panelists and other experts from the EHT collaboration will be available for interviews.

NSF will issue a press release the morning of the press conference along with supporting material. Supporting material will also be available at https://nsf.gov/blackholes.

In addition to the press briefing in the U.S., press conferences will be held simultaneously in Garching bei München (near Munich), Mexico City, Santiago de Chile, Shanghai, Tokyo, and Taipei. If you wish to embed the press conference in your online feed, you may do so from the NSF direct livestream link. The NSF Black Holes page includes additional information about exploring and studying black holes.

A separate panel of EHT researchers will participate in a public Q&amp;A panel at 10:30 a.m. EDT. The public Q&amp;A panel will also be available to view on the NSF Black Holes Website and NSF's Facebook page. Participants include:

Kazu Akiyama, Research Scientist, MIT Haystack Observatory
Richard Anantua, Assistant Professor of Physics &amp; Astronomy at the University of Texas at San Antonio and Associate at the Harvard College Observatory
Daryl Haggard, Associate Professor of Physics at McGill University and the McGill Space Institute
Lia Medeiros, NSF Postdoctoral Fellow at the Institute for Advanced Study
Dom Pesce, Astrophysicist, Center for Astrophysics | Harvard &amp; Smithsonian and Black Hole Initiative at Harvard University
For further information about EHT, please visit the Event Horizon Telescope webpage.

The information in this press advisory is strictly for media planning purposes and is embargoed until May 12, 2022.

-NSF-

Speculation here:

https://www.cnet.com/google-amp/news/astronomers-tease-groundbreaking-result-of-milky-ways-black-hole/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/02/2022 03:37 pm
NASA’s Black Hole Orrery:

https://youtu.be/NqOhCBRnrnA
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/05/2022 07:54 am
A 62-minute orbital period black widow binary in a wide hierarchical triple

Abstract
Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original ‘black widow’, the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20)1, high-energy emission originating from the pulsar2 is irradiating and may eventually destroy3 a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars4, allowing for robust tests of the neutron star equation of state. Here we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate, the optical flux of which varies by a factor of more than ten. ZTF J1406+1222 pushes the boundaries of evolutionary models5, falling below the 80-minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low-metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic Centre, making it a probe of formation channels, neutron star kick physics6 and binary evolution.

https://www.nature.com/articles/s41586-022-04551-1
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/12/2022 01:40 pm
SGR-A*

https://youtu.be/3xgc1651Als
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 05/12/2022 01:49 pm
eso2208-eht-mw — Science Release
Astronomers reveal first image of the black hole at the heart of our galaxy

Today, at simultaneous press conferences around the world, including at the European Southern Observatory (ESO) headquarters in Germany, astronomers have unveiled the first image of the supermassive black hole at the centre of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the centre of most galaxies. The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes.

The image is a long-anticipated look at the massive object that sits at the very centre of our galaxy. Scientists had previously seen stars orbiting around something invisible, compact, and very massive at the centre of the Milky Way. This strongly suggested that this object — known as Sagittarius A* (Sgr A*, pronounced "sadge-ay-star") — is a black hole, and today’s image provides the first direct visual evidence of it. 

Although we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. 

“We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity," said EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. "These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy, and offer new insights on how these giant black holes interact with their surroundings." The EHT team's results are being published today in a special issue of The Astrophysical Journal Letters.

Because the black hole is about 27 000 light-years away from Earth, it appears to us to have about the same size in the sky as a doughnut on the Moon. To image it, the team created the powerful EHT, which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope [1]. The EHT observed Sgr A* on multiple nights in 2017, collecting data for many hours in a row, similar to using a long exposure time on a camera.

In addition to other facilities, the EHT network of radio observatories includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO on behalf of its member states in Europe. Europe also contributes to the EHT observations with other radio observatories — the IRAM 30-meter telescope in Spain and, since 2018, the NOrthern Extended Millimeter Array (NOEMA) in France — as well as a supercomputer to combine EHT data hosted by the Max Planck Institute for Radio Astronomy in Germany. Moreover, Europe contributed with funding to the EHT consortium project through grants by the European Research Council and by the Max Planck Society in Germany.

“It is very exciting for ESO to have been playing such an important role in unravelling the mysteries of black holes, and of Sgr A* in particular, over so many years,” commented ESO Director General Xavier Barcons. “ESO not only contributed to the EHT observations through the ALMA and APEX facilities but also enabled, with its other observatories in Chile, some of the previous breakthrough observations of the Galactic centre.” [2]

The EHT achievement follows the collaboration’s 2019 release of the first image of a black hole, called M87*, at the centre of the more distant Messier 87 galaxy.

The two black holes look remarkably similar, even though our galaxy’s black hole is more than a thousand times smaller and less massive than M87* [3]. "We have two completely different types of galaxies and two very different black hole masses, but closeto the edge of these black holesthey look amazingly similar,” says Sera Markoff, Co-Chair of the EHT Science Council and a professor of theoretical astrophysics at the University of Amsterdam, the Netherlands."This tells us that General Relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes.”

This achievement was considerably more difficult than for M87*, even though Sgr A* is much closer to us. EHT scientist Chi-kwan (‘CK’) Chan, from Steward Observatory and Department of Astronomy and the Data Science Institute of the University of Arizona, USA, explains: “The gas in the vicinity of the black holes moves at the same speed — nearly as fast as light — around both Sgr A* and M87*. But where gas takes days to weeks to orbit the larger M87*, in the much smaller Sgr A* it completes an orbit in mere minutes. This means the brightness and pattern of the gas around Sgr A* were changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail.”

The researchers had to develop sophisticated new tools that accounted for the gas movement around Sgr A*. While M87* was an easier, steadier target, with nearly all images looking the same, that was not the case for Sgr A*. The image of the Sgr A* black hole is an average of the different images the team extracted, finally revealing the giant lurking at the centre of our galaxy for the first time. 

The effort was made possible through the ingenuity of more than 300 researchers from 80 institutes around the world that together make up the EHT Collaboration. In addition to developing complex tools to overcome the challenges of imaging Sgr A*, the team worked rigorously for five years, using supercomputers to combine and analyse their data, all while compiling an unprecedented library of simulated black holes to compare with the observations. 

Scientists are particularly excited to finally have images of two black holes of very different sizes, which offers the opportunity to understand how they compare and contrast. They have also begun to use the new data to test theories and models of how gas behaves around supermassive black holes. This process is not yet fully understood but is thought to play a key role in shaping the formation and evolution of galaxies.

“Now we can study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” said EHT scientist Keiichi Asada from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei. “We have images for two black holes — one at the large end and one at the small end of supermassive black holes in the Universe — so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.” 

Progress on the EHT continues: a major observation campaign in March 2022 included more telescopes than ever before. The ongoing expansion of the EHT network and significant technological upgrades will allow scientists to share even more impressive images as well as movies of black holes in the near future.

Notes
[1] The individual telescopes involved in the EHT in April 2017, when the observations were conducted, were: the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXperiment (APEX), the IRAM 30-meter Telescope, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the UArizona Submillimeter Telescope (SMT), the South Pole Telescope (SPT). Since then, the EHT has added the Greenland Telescope (GLT), the NOrthern Extended Millimeter Array (NOEMA) and the UArizona 12-meter Telescpe on Kitt Peak to its network.

ALMA is a partnership of the European Southern Observatory (ESO; Europe, representing its member states), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, together with the National Research Council (Canada), the Ministry of Science and Technology (MOST; Taiwan), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan), and Korea Astronomy and Space Science Institute (KASI; Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, the Associated Universities, Inc./National Radio Astronomy Observatory (AUI/NRAO) and the National Astronomical Observatory of Japan (NAOJ). APEX, a collaboration between the Max Planck Institute for Radio Astronomy (Germany), the Onsala Space Observatory (Sweden) and ESO, is operated by ESO. The 30-meter Telescope is operated by IRAM (the IRAM Partner Organizations are MPG [Germany], CNRS [France] and IGN [Spain]). The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; ASIAA; KASI; the National Astronomical Research Institute of Thailand; the Center for Astronomical Mega-Science and organisations in the United Kingdom and Canada. The LMT is operated by INAOE and UMass, the SMA is operated by Center for Astrophysics | Harvard &amp; Smithsonian and ASIAA and the UArizona SMT is operated by the University of Arizona. The SPT is operated by the University of Chicago with specialised EHT instrumentation provided by the University of Arizona.

The Greenland Telescope (GLT) is operated by ASIAA and the Smithsonian Astrophysical Observatory (SAO). The GLT is part of the ALMA-Taiwan project, and is supported in part by the Academia Sinica (AS) and MOST. NOEMA is operated by IRAM and the UArizona 12-meter telescope at Kitt Peak is operated by the University of Arizona.

[2] A strong basis for the interpretation of this new image was provided by previous research carried out on Sgr A*. Astronomers have known the bright, dense radio source at the centre of the Milky Way in the direction of the constellation Sagittarius since the 1970s. By measuring the orbits of several stars very close to our galactic centre over a period of 30 years, teams led by Reinhard Genzel (Director at the Max –Planck Institute for Extraterrestrial Physics in Garching near Munich, Germany) and Andrea M. Ghez (Professor in the Department of Physics and Astronomy at the University of California, Los Angeles, USA) were able to conclude that the most likely explanation for an object of this mass and density is a supermassive black hole. ESO's facilities (including the Very Large Telescope and the Very Large Telescope Interferometer) and the Keck Observatory were used to carry out this research, which shared the 2020 Nobel Prize in Physics.

[3] Black holes are the only objects we know of where mass scales with size. A black hole a thousand times smaller than another is also a thousand times less massive. 

More information
This research was presented in six papers published today in The Astrophysical Journal Letters.

The EHT collaboration involves more than 300 researchers from Africa, Asia, Europe, North and South America. The international collaboration aims to capture the most detailed black hole images ever obtained by creating a virtual Earth-sized telescope. Supported by considerable international efforts, the EHT links existing telescopes using novel techniques — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.

The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the Center for Astrophysics | Harvard &amp; Smithsonian, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, and Radboud University.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

APEX, Atacama Pathfinder EXperiment, is a 12-metre diameter telescope, operating at millimetre and submillimetre wavelengths — between infrared light and radio waves. ESO operates APEX at one of the highest observatory sites on Earth, at an elevation of 5100 metres, high on the Chajnantor plateau in Chile’s Atacama region. The telescope is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO), and ESO.

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates APEX and ALMA on Chajnantor, two facilities that observe the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.

Links
Main papers:
Paper I: The Shadow of the Supermassive Black Hole in the Center of the Milky Way
Paper II: EHT and Multi-wavelength Observations, Data Processing, and Calibration
Paper III: Imaging of the Galactic Center Supermassive Black Hole
Paper IV: Variability, Morphology, and Black Hole Mass
Paper V: Testing Astrophysical Models of the Galactic Center Black Hole
Paper VI: Testing the Black Hole Metric
Supplementary papers:
Selective Dynamical Imaging of Interferometric Data
Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign
A Universal Power Law Prescription for Variability from Synthetic Images of Black Hole Accretion Flows
Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI
ESO EHT web page
EHT Website &amp; Press Release
Images of ALMA
Images of APEX
Contacts
Geoffrey Bower
EHT Project Scientist, Institute of Astronomy and Astrophysics, Academic Sinica, Taipei and University of Hawaii at Mnoa, US
Tel: +1-808-961-2945
Email: [email protected]

Huib Jan van Langevelde
EHT Project Director, JIVE and University of Leiden
Leiden, The Netherlands
Tel: +31-521-596515
Email: [email protected]

Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: [email protected]

Connect with ESO on social media

https://www.eso.org/public/news/eso2208-eht-mw/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/12/2022 01:57 pm
Quote
The latest observations are already giving intriguing hints about the nature of our own black hole. Simulations based on the data hint that our black hole’s angle of rotation is not neatly aligned with the galactic plain, but is off-kilter by about 30 degrees. The observations also suggest that SgrA* is in a dormant state, in contrast with some black holes, including M87, which feature vast, powerful jets that blast light and matter from the black hole’s poles into intergalactic space. “If a big star fell in, which would happen every 10,000 years, that would wake it up for a short amount of time and we’d see things brighten up,” said Markoff.

https://amp.theguardian.com/science/2022/may/12/supermassive-black-hole-centre-milky-way-first-time-sagittarius-a-
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/16/2022 07:58 am
Bilayer Graphene Inspires Two-Universe Cosmological Model

Quote
In a new paper in Physical Review Research(link is external), JQI Fellow Victor Galitski and JQI graduate student Alireza Parhizkar have explored the imaginative possibility that our reality is only one half of a pair of interacting worlds. Their mathematical model may provide a new perspective for looking at fundamental features of reality—including why our universe expands the way it does and how that relates to the most miniscule lengths allowed in quantum mechanics. These topics are crucial to understanding our universe and are part of one of the great mysteries of modern physics.

The pair of scientists stumbled upon this new perspective when they were looking into research on sheets of graphene—single atomic layers of carbon in a repeating hexagonal pattern. They realized that experiments on the electrical properties of stacked sheets of graphene produced results that looked like little universes and that the underlying phenomenon might generalize to other areas of physics. In stacks of graphene, new electrical behaviors arise from interactions between the individual sheets, so maybe unique physics could similarly emerge from interacting layers elsewhere—perhaps in cosmological theories about the entire universe.

Quote
The new model produced additional results the researchers find intriguing. As they put together the math, they found that part of the model looked like important fields that are part of reality. The more detailed model still suggests that two worlds could explain a small cosmological constant and provides details about how such a bi-world might imprint a distinct signature on the cosmic background radiation—the light that lingers from the earliest times in the universe.

This signature could possibly be seen—or definitively not be seen—in real world measurements. So future experiments could determine if this unique perspective inspired by graphene deserves more attention or is merely an interesting novelty in the physicists’ toy bin.

“We haven't explored all the effects—that's a hard thing to do, but the theory is falsifiable experimentally, which is a good thing,” Parhizkar says. “If it's not falsified, then it's very interesting because it solves the cosmological constant problem while describing many other important parts of physics. I personally don't have my hopes up for that— I think it is actually too big to be true.”

https://jqi.umd.edu/news/bilayer-graphene-inspires-two-universe-cosmological-model

Related paper:

Moiré Gravity and Cosmology

The vacuum catastrophe is a fundamental puzzle, where the observed scales of the cosmological constant are many orders of magnitude smaller than the natural scales expected in the theory. This work proposes a new "bi-world" construction that may offer an insight into the cosmological constant problem. The model includes a (3+1)-dimensional manifold with two different geometries and matter fields residing on them. The diffeomorphism invariance and causality highly constrain the two metrics to be conformally related, ημν=2gμν. This reduces the theory to a standard single-world description, but introduces a new inherently geometrical "moiré field," . Interestingly, the moiré field has the character of both a dilaton and Higgs field familiar in the conventional theory. Integrating out the moiré field naturally gives rise to the Starobinsky action and inflationary dynamics. In the framework of the Friedmann-Lemaitre-Robertson-Walker solution, we reduce an effective action for the moiré field to that of a particle moving in a Mexican hat potential. The equations of motion are then solved numerically and the moiré field is shown to approach a Mexican-hat minimum in an oscillatory fashion, which is accompanied by the decay of the Hubble parameter. Under additional reasonable assumptions, the vacuum energy asymptotically approaches zero in the end of inflationary evolution. The physics presented here shares similarities with the moiré phenomena in condensed matter and elsewhere, where two similar structures superimposed upon give rise to a superstructure with low emergent energy scales compared to the native theories.

https://arxiv.org/abs/2204.06574
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/27/2022 08:51 am
Sonification of NGC 1300:

https://youtu.be/zyf1UDm-GyU
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 06/01/2022 07:10 pm
Imaging stars with quantum error correction
Quote
The development of high-resolution, large-baseline optical interferometers would revolutionize astro- nomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature.
In a nutshell, we all love very long baseline interferometry (VLBI) for radio telescopes to image black holes in M87 and our own galaxy. Now, if we could build an optical telescope with the baseline of Earth, wouldn't that be fun? While theoretical work at the moment, we'd love to see an experimental validation of the concept.

https://arxiv.org/pdf/2204.06044.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/08/2022 01:46 pm
Galaxy cluster collision created 1.6 million mile shockwave:

https://youtu.be/lJmFj0upmo0
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 06/11/2022 02:34 am
I heard about a small telescope mission called Toliman ( Telescope for Orbit Locus Interferometric Monitoring of our Astronomical Neighborhood):
https://en.wikipedia.org/wiki/TOLIMAN

It is a privately funded scope for observing Alpha Centauri among other targets. Curious if anyone knows details; I had been informed the foundation linked to it might have assisted in a potential discovery of a Neptune-esque body around A, confirmation pending which the scope might assist in.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/25/2022 10:47 am
The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc

Abstract
We report the discovery of a multi-planetary system transiting the M0 V dwarf HD 260655 (GJ 239, TOI-4599). The system consists of at least two transiting planets, namely HD 260655 b, with a period of 2.77 d, a radius of R$_b$ = 1.240$\pm$0.023 R$_\oplus$, a mass of M$_b$ = 2.14$\pm$0.34 M$_\oplus$, and a bulk density of $\rho_b$ = 6.2$\pm$1.0 g cm$^{-3}$, and HD 260655 c, with a period of 5.71 d, a radius of R$_c$ = 1.533$^{+0.051}_{-0.046}$ R$_\oplus$, a mass of M$_c$ = 3.09$\pm$0.48 M$_\oplus$, and a bulk density of $\rho_c$ = 4.7$^{+0.9}_{-0.8}$ g cm$^{-3}$. The planets were detected in transit by the TESS mission and confirmed independently with archival and new precise radial velocities obtained with the HIRES and CARMENES instruments since 1998 and 2016, respectively. At a distance of 10 pc, HD 260655 becomes the fourth closest known multi-transiting planet system after HD 219134, LTT 1445 A, and AU Mic. Due to the apparent brightness of the host star (J = 6.7 mag), both planets are among the most suitable rocky worlds known today for atmospheric studies with the JWST, both in transmission and emission.

https://www.researchgate.net/publication/360098320_The_HD_260655_system_Two_rocky_worlds_transiting_a_bright_M_dwarf_at_10_pc

https://www.forbes.com/sites/jamiecartereurope/2022/06/24/found-two-new-rocky-earth-sized-planets-in-our-cosmic-backyard-and-there-could-be-more/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/28/2022 04:06 pm
The variability behavior of NGC 925 ULX-3

We report the results of a 2019-2021 monitoring campaign with Swift and associated target-of-opportunity observations with XMM-Newton and NuSTAR, examining the spectral and timing behavior of the highly variable ultraluminous X-ray source (ULX) NGC 925 ULX-3. We find that the source exhibits a 127-128 day periodicity, with fluxes typically ranging from 1e-13 to 8e-13 ergs/s/cm2. We do not find strong evidence for a change in period over the time that NGC 925 ULX-3 has been observed, although the source may have been in a much lower flux state when first observed with Chandra in 2005. We do not detect pulsations, and we place an upper limit on the pulsed fraction of ~40% in the XMM-Newton band, consistent with some previous pulsation detections at low energies in other ULXs. The source exhibits a typical ULX spectrum that turns over in the NuSTAR band and can be fitted using two thermal components. These components have a high temperature ratio that may indicate the lack of extreme inner disk truncation by a magnetar-level magnetic field. We examine the implications for a number of different models for superorbital periods in ULXs, finding that a neutron star with a magnetic field of ~10^12 G may be plausible for this source. The future detection of pulsations from this source would allow for the further testing and constraining of such models.

https://arxiv.org/abs/2206.08397
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/28/2022 04:15 pm
Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino

ABSTRACT
The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one high-energy neutrino was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino. Our observations, including a bright dust echo and soft late-time x-ray emission, further support a TDE origin of this flare. The probability of finding two such bright events by chance is just 0.034%. We evaluate several models for neutrino production and show that AT2019fdr is capable of producing the observed high-energy neutrino, reinforcing the case for TDEs as neutrino sources.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.221101
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/05/2022 11:04 am
Observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner.

Quote
Today, at the CERN seminar, the LHCb Collaboration reported the observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner. These results will also be presented at the ICHEP 2022 International Conference on High Energy Physics in Bologna, Italy, starting tomorrow.

https://lhcb-outreach.web.cern.ch/2022/07/05/observation-of-a-strange-pentaquark-a-doubly-charged-tetraquark-and-its-neutral-partner/

https://phys.org/news/2022-07-lhcb-exotic-particles-pentaquark-first-ever.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/08/2022 09:05 am
Quote
We can model the motions of planets in the Solar System quite accurately using Newton’s laws of physics. But in the early 1970s, scientists noticed that this didn’t work for disc galaxies – stars at their outer edges, far from the gravitational force of all the matter at their centre – were moving much faster than Newton’s theory predicted.

This made physicists propose that an invisible substance called “dark matter” was providing extra gravitational pull, causing the stars to speed up – a theory that’s become hugely popular. However, in a recent review my colleagues and I suggest that observations across a vast range of scales are much better explained in an alternative theory of gravity proposed by Israeli physicist Mordehai Milgrom in 1982 called Milgromian dynamics or Mond – requiring no invisible matter.

https://theconversation.com/dark-matter-our-review-suggests-its-time-to-ditch-it-in-favour-of-a-new-theory-of-gravity-186344

Here’s the review referred to above.

From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity

Abstract
Astronomical observations reveal a major deficiency in our understanding of physics—the detectable mass is insufficient to explain the observed motions in a huge variety of systems given our current understanding of gravity, Einstein’s General theory of Relativity (GR). This missing gravity problem may indicate a breakdown of GR at low accelerations, as postulated by Milgromian dynamics (MOND). We review the MOND theory and its consequences, including in a cosmological context where we advocate a hybrid approach involving light sterile neutrinos to address MOND’s cluster-scale issues. We then test the novel predictions of MOND using evidence from galaxies, galaxy groups, galaxy clusters, and the large-scale structure of the universe. We also consider whether the standard cosmological paradigm (Λ
CDM) can explain the observations and review several previously published highly significant falsifications of it. Our overall assessment considers both the extent to which the data agree with each theory and how much flexibility each has when accommodating the data, with the gold standard being a clear a priori prediction not informed by the data in question. Our conclusion is that MOND is favoured by a wealth of data across a huge range of astrophysical scales, ranging from the kpc scales of galactic bars to the Gpc scale of the local supervoid and the Hubble tension, which is alleviated in MOND through enhanced cosmic variance. We also consider several future tests, mostly at scales much smaller than galaxies. View Full-Text

https://www.mdpi.com/2073-8994/14/7/1331
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/14/2022 06:29 am
Sub-second periodicity in a fast radio burst

Abstract
Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that are visible at distances of billions of light years1. The nature of their progenitors and their emission mechanism remain open astrophysical questions2. Here we report the detection of the multicomponent FRB 20191221A and the identification of a periodic separation of 216.8(1) ms between its components, with a significance of 6.5σ. The long (roughly 3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. Such short periodicity provides strong evidence for a neutron-star origin of the event. Moreover, our detection favours emission arising from the neutron-star magnetosphere3,4, as opposed to emission regions located further away from the star, as predicted by some models5.

https://www.nature.com/articles/s41586-022-04841-8

Quote
A fast radio burst (FRB) dubbed FRB 20191221A persists for up to three seconds, about 1,000 times longer than the average FRB; within this window, astronomers from the CHIME/FRB Collaboration detected bursts that repeat every 217 ms in a clear periodic pattern, similar to a beating heart.

http://www.sci-news.com/astronomy/heartbeat-fast-radio-burst-10998.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/15/2022 06:20 am
Early crustal processes revealed by the ejection site of the oldest martian meteorite

Abstract
The formation and differentiation of the crust of Mars in the first tens of millions of years after its accretion can only be deciphered from incredibly limited records. The martian breccia NWA 7034 and its paired stones is one of them. This meteorite contains the oldest martian igneous material ever dated: ~4.5 Ga old. However, its source and geological context have so far remained unknown. Here, we show that the meteorite was ejected 5–10 Ma ago from the north-east of the Terra Cimmeria—Sirenum province, in the southern hemisphere of Mars. More specifically, the breccia belongs to the ejecta deposits of the Khujirt crater formed 1.5 Ga ago, and it was ejected as a result of the formation of the Karratha crater 5–10 Ma ago. Our findings demonstrate that the Terra Cimmeria—Sirenum province is a relic of the differentiated primordial martian crust, formed shortly after the accretion of the planet, and that it constitutes a unique record of early crustal processes. This province is an ideal landing site for future missions aiming to unravel the first tens of millions of years of the history of Mars and, by extension, of all terrestrial planets, including the Earth.

https://www.nature.com/articles/s41467-022-31444-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/15/2022 03:53 pm
Apparently they are considering naming future Covid variants after constellations. Not sure how I feel about that idea of co-opting the names for something like Covid.

Quote
The World Health Organization has named variants of interest or concern using letters of the Greek alphabet “to assist with public discussions.” The decision stemmed last year from meetings with scientists and WHO officials to come up with easy-to-pronounce names and stop the “stigmatizing labels” from when many people described variants by the countries where they were identified.
They considered everything from bird species to Greek gods. Problems that popped up included trademarks and the possibility they could eventually run out of Greek letters.
“With Centaurus, as far as naming goes, it’s fine in that it’s not geographical, it’s not harmful, it’s not misleading. Nobody’s getting it mixed up with a constellation,” said Hodcroft, who was part of the group that brainstormed nomenclature. “But it may not be so lucky next time.”

She described the Greek letter system as “a success” and said there was a plan to use constellation names afterward, but she added it may have been easier before when variants were “all much more distinct.”

https://www.washingtonpost.com/world/2022/07/14/centaurus-coronavirus-subvariant-world-health/
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 07/15/2022 07:38 pm
Apparently they are considering naming future Covid variants after constellations. Not sure how I feel about that idea of co-opting the names for something like Covid.

Guess they think the Greek alphabet ends at omicron rather than omega... an O is an O, apparently.

Wonder how "much less distinct" this "Centaurus" is with respect to B.1.1.529.

Shouldn't surprise us, with the abysmal levels of public discourse about the pandemic, that they're just aiming at the "Andromeda Strain" for the lolz.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/18/2022 04:37 pm
‘Black Hole Police’ Spot Extragalactic Black Hole (ESOcast 255 Light)

https://youtu.be/k3OO4SOj2K4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/21/2022 07:14 pm
Neutron stars: New telescope detects dead suns colliding https://www.bbc.co.uk/news/science-environment-61911047
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 07/22/2022 01:31 pm
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260
Possible detection of Solar Axions.

https://www.bbc.co.uk/news/science-environment-53085260

From the horse's mouth: https://science.purdue.edu/xenon1t/?p=1474

The presentation in question: https://www.dropbox.com/s/vrq49tldjdfvnjh/shockley20200617.pdf?dl=0

Note this result is very much in tension with many other processes which should be directly influenced by axion production. A good (technical) contextualization is available in Resonàaances from a theoretician's point of view: http://resonaances.blogspot.com/2020/06/hail-xenon-excess.html Bottom line: if this excess is solar axions, the astrophysical limits on axion cooling on red giants and white dwarves should get a major overhaul (which would come with lots of implications of their own). Meanwhile, unaccounted-for contamination in that pre-cutoff energy area is notoriously insidious in many experiments' analyses.

In any case, very cool result from a great group I've had lots of contact with over the last few years, including being physically inside their detector once, prior to fluid filling :)

Predictably: it was tritium contamination all along!

http://xenonexperiment.org/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/22/2022 01:40 pm
Why Jupiter doesn’t have substantial rings like Saturn.

The Dynamical Viability of an Extended Jupiter Ring System

Planetary rings are often speculated as being a relatively common attribute of giant planets, partly based on their prevalence within the Solar System. However, their formation and sustainability remain a topic of open discussion, and the most massive planet within our planetary system harbors a very modest ring system. Here, we present the results of a N-body simulation that explores dynamical constraints on the presence of substantial ring material for Jupiter. Our simulations extend from within the rigid satellite Roche limit to 10\% of the Jupiter Hill radius, and include outcomes from 106 and 107 year integrations. The results show possible regions of a sustained dense ring material presence around Jupiter that may comprise the foundation for moon formation. The results largely demonstrate the truncation of stable orbits imposed by the Galilean satellites, and dynamical desiccation of dense ring material within the range ∼3--29 Jupiter radii. We discuss the implications of these results for exoplanets, and the complex relationship between the simultaneous presence of rings and massive moon systems.

https://arxiv.org/abs/2207.06434
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/22/2022 06:07 pm
Further to above.

Quote
Potential hints of weird new particles in a dark matter detector have evaporated with new data.

Following up on a beguiling result from its predecessor experiment, the XENONnT experiment found no sign of extra blips that could point to new particles or another phenomenon, scientists report July 22 in Vienna at the International Conference on Identification of Dark Matter.

https://www.sciencenews.org/article/xenonnt-axions-dark-matter-experiment
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/29/2022 06:19 am
Quote
What did you do with the extra 1.59 milliseconds on Wednesday, June 29, 2022?

As reported by TimeAndDate.com, on that date our planet set a new fastest record—as far as scientists can tell—for completing one rotation.

Hang on! Earth takes exactly 24 hours to rotate once on its axis, right? Almost, yes, but not exactly.

https://www.forbes.com/sites/jamiecartereurope/2022/07/28/earth-is-suddenly-spinning-faster-why-our-planet-just-recorded-its-shortest-day-since-records-began/
Title: Re: Astronomy & Planetary Science Thread
Post by: briantipton on 07/29/2022 03:21 pm
"Melting of glaciers means less ice at the poles" is not a logical explanation. Less mass at the poles would mean moving mass to a larger radius of revolution which would slow, not increase the rate of spin. Maybe less ice in glaciers (and ignoring the statement about the poles) could result in going mass to a lower radius and increase the rate of spin, but that would be very sensitive to the latitude of the glaciers in question. I'd look elsewhere for an explanation
Title: Re: Astronomy & Planetary Science Thread
Post by: whitelancer64 on 07/29/2022 03:51 pm
"Melting of glaciers means less ice at the poles" is not a logical explanation. Less mass at the poles would mean moving mass to a larger radius of revolution which would slow, not increase the rate of spin. Maybe less ice in glaciers (and ignoring the statement about the poles) could result in going mass to a lower radius and increase the rate of spin, but that would be very sensitive to the latitude of the glaciers in question. I'd look elsewhere for an explanation

Less ice sheet mass at the poles also means the ground that was underneath the ice (now melted) will rebound. This is already being seen in Greenland, for example.

https://en.wikipedia.org/wiki/Post-glacial_rebound

I would presume this produces a net result of narrowing the equator, meaning faster spin.
Title: Re: Astronomy & Planetary Science Thread
Post by: Stan-1967 on 07/29/2022 03:51 pm

It doesn’t help that the person writing the article says we just our shortest day,  while the article says our day is now 1.6 milliseconds longer.  Maybe he/she is a journalism major, and not a science writer.  Pesky math.

More information on causes would be interesting.  Maybe warmer weather ,  especially in the tropics,  drives more water vapor high into the atmosphere,  thereby slowing earths rotation rate
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 07/30/2022 01:48 am
Quote
Hang on! Earth takes exactly 24 hours to rotate once on its axis, right? Almost, yes, but not exactly.

Earth takes 23 hours 56 minutes to rotate once on its axis (one sidereal day). A synodic or calendar day is 24 hours long and is the time between successive noons (when the Sun is at its highest in the sky).
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/30/2022 06:41 am
This is the original article, and what I should have posted instead as it appears a clearer article.

https://www.timeanddate.com/news/astronomy/shortest-day-2022
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/06/2022 04:08 pm
Tonga Eruption Blasted Unprecedented Amount of Water Into Stratosphere

The huge amount of water vapor hurled into the atmosphere, as detected by NASA’s Microwave Limb Sounder, could end up temporarily warming Earth’s surface.

When the Hunga Tonga-Hunga Ha’apai volcano erupted on Jan. 15, it sent a tsunami racing around the world and set off a sonic boom that circled the globe twice. The underwater eruption in the South Pacific Ocean also blasted an enormous plume of water vapor into Earth’s stratosphere – enough to fill more than 58,000 Olympic-size swimming pools. The sheer amount of water vapor could be enough to temporarily affect Earth’s global average temperature.

“We’ve never seen anything like it,” said Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Southern California. He led a new study examining the amount of water vapor that the Tonga volcano injected into the stratosphere, the layer of the atmosphere between about 8 and 33 miles (12 and 53 kilometers) above Earth’s surface.

In the study, published in Geophysical Research Letters, Millán and his colleagues estimate that the Tonga eruption sent around 146 teragrams (1 teragram equals a trillion grams) of water vapor into Earth’s stratosphere – equal to 10% of the water already present in that atmospheric layer. That’s nearly four times the amount of water vapor that scientists estimate the 1991 Mount Pinatubo eruption in the Philippines lofted into the stratosphere.

Millán analyzed data from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite, which measures atmospheric gases, including water vapor and ozone. After the Tonga volcano erupted, the MLS team started seeing water vapor readings that were off the charts. “We had to carefully inspect all the measurements in the plume to make sure they were trustworthy,” said Millán.

A Lasting Impression

Volcanic eruptions rarely inject much water into the stratosphere. In the 18 years that NASA has been taking measurements, only two other eruptions – the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile – sent appreciable amounts of water vapor to such high altitudes. But those were mere blips compared to the Tonga event, and the water vapor from both previous eruptions dissipated quickly. The excess water vapor injected by the Tonga volcano, on the other hand, could remain in the stratosphere for several years.

This extra water vapor could influence atmospheric chemistry, boosting certain chemical reactions that could temporarily worsen depletion of the ozone layer. It could also influence surface temperatures. Massive volcanic eruptions like Krakatoa and Mount Pinatubo typically cool Earth’s surface by ejecting gases, dust, and ash that reflect sunlight back into space. In contrast, the Tonga volcano didn’t inject large amounts of aerosols into the stratosphere, and the huge amounts of water vapor from the eruption may have a small, temporary warming effect, since water vapor traps heat. The effect would dissipate when the extra water vapor cycles out of the stratosphere and would not be enough to noticeably exacerbate climate change effects.

The sheer amount of water injected into the stratosphere was likely only possible because the underwater volcano’s caldera – a basin-shaped depression usually formed after magma erupts or drains from a shallow chamber beneath the volcano – was at just the right depth in the ocean: about 490 feet (150 meters) down. Any shallower, and there wouldn’t have been enough seawater superheated by the erupting magma to account for the stratospheric water vapor values Millán and his colleagues saw. Any deeper, and the immense pressures in the ocean’s depths could have muted the eruption.

The MLS instrument was well situated to detect this water vapor plume because it observes natural microwave signals emitted from Earth’s atmosphere. Measuring these signals enables MLS to “see” through obstacles like ash clouds that can blind other instruments measuring water vapor in the stratosphere. “MLS was the only instrument with dense enough coverage to capture the water vapor plume as it happened, and the only one that wasn’t affected by the ash that the volcano released,” said Millán.

The MLS instrument was designed and built by JPL, which is managed for NASA by Caltech in Pasadena. NASA’s Goddard Space Flight Center manages the Aura mission.

Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
[email protected] / [email protected]

2022-112

https://www.nasa.gov/feature/jpl/tonga-eruption-blasted-unprecedented-amount-of-water-into-stratosphere
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/07/2022 03:41 pm
We found some strange radio sources in a distant galaxy cluster. They’re making us rethink what we thought we knew.

Quote
The universe is littered with galaxy clusters – huge structures piled up at the intersections of the cosmic web. A single cluster can span millions of light-years across and be made up of hundreds, or even thousands, of galaxies.

However, these galaxies represent only a few percent of a cluster’s total mass. About 80% of it is dark matter, and the rest is a hot plasma “soup”: gas heated to above 10,000,000 and interwoven with weak magnetic fields.

We and our international team of colleagues have identified a series of rarely observed radio objects – a radio relic, a radio halo and fossil radio emission – within a particularly dynamic galaxy cluster called Abell 3266. They defy existing theories about both the origins of such objects and their characteristics.

https://theconversation.com/we-found-some-strange-radio-sources-in-a-distant-galaxy-cluster-theyre-making-us-rethink-what-we-thought-we-knew-187631

Related paper:

Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA

ABSTRACT
Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder (0.8–1.1 GHz) and the Australia Telescope Compact Array (1.1–3.1 GHz). These deep observations provide new insights into recently reported diffuse non-thermal phenomena associated with the intracluster medium, including a ‘wrong-way’ relic, a fossil plasma source, and an as-yet unclassified central diffuse ridge, which we reveal comprises the brightest part of a large-scale radio halo detected here for the first time. The ‘wrong-way’ relic is highly atypical of its kind: it exhibits many classical signatures of a shock-related radio relic, while at the same time exhibiting strong spectral steepening. While radio relics are generally consistent with a quasi-stationary shock scenario, the ‘wrong-way’ relic is not. We study the spectral properties of the fossil plasma source; it exhibits an ultrasteep and highly curved radio spectrum, indicating an extremely aged electron population. The larger scale radio halo fills much of the cluster centre, and presents a strong connection between the thermal and non-thermal components of the intracluster medium, along with evidence of substructure. Whether the central diffuse ridge is simply a brighter component of the halo, or a mini-halo, remains an open question. Finally, we study the morphological and spectral properties of the multiple complex radio galaxies in this cluster in unprecedented detail, tracing their evolutionary history.

https://academic.oup.com/mnras/article/515/2/1871/6650456?login=false
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/12/2022 08:43 am
Don’t forget to look out for Peresids in the UK tonight and tomorrow.

https://ukmeteornetwork.co.uk/showers/2022-perseids/
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 08/12/2022 02:34 pm
Don’t forget to look out for Peresids in the UK tonight and tomorrow.

https://ukmeteornetwork.co.uk/showers/2022-perseids/
Whoever scheduled the full moon and the perseids on the same night made a mistake!
Also grumble grumble storm clouds.
Title: Re: Astronomy & Planetary Science Thread
Post by: Hog on 08/12/2022 07:45 pm
Don’t forget to look out for Peresids in the UK tonight and tomorrow.

https://ukmeteornetwork.co.uk/showers/2022-perseids/
Whoever scheduled the full moon and the perseids on the same night made a mistake!
Also grumble grumble storm clouds.
Plus ONE!  The Perseid peak certainly masked a bunch of activity last night.  The Moonrise at 8:40'ish EDT was impressive however.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/13/2022 04:47 pm
Supergiant Betelgeuse had a never-before-seen massive eruption

Quote
The red supergiant Betelgeuse, a colossal star in the Orion constellation, experienced a massive stellar eruption -- the likes of which have never been seen before, according to astronomers.

Quote
Now, astronomers have analyzed data from the Hubble Space Telescope and other observatories, and they believe the star experienced a titanic surface mass ejection, losing a substantial part of its visible surface.

"We've never before seen a huge mass ejection of the surface of a star. We are left with something going on that we don't completely understand," said Andrea Dupree, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts, in a statement.

"It's a totally new phenomenon that we can observe directly and resolve surface details with Hubble. We're watching stellar evolution in real time."

The amount of mass lost is incredible.

Quote
But the surface mass ejection Betelgeuse experienced released more than 400 billion times as much mass as a typical coronal mass ejection from the sun.

https://amp.cnn.com/cnn/2022/08/12/world/betelgeuse-star-recovery-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Hog on 08/15/2022 01:30 am

Quote
But the surface mass ejection Betelgeuse experienced released more than 400 billion times as much mass as a typical coronal mass ejection from the sun.

https://amp.cnn.com/cnn/2022/08/12/world/betelgeuse-star-recovery-scn/index.html
That's a serious ejection.  I hope my Starlink is hardened against that.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/15/2022 08:58 am

Quote
But the surface mass ejection Betelgeuse experienced released more than 400 billion times as much mass as a typical coronal mass ejection from the sun.

https://amp.cnn.com/cnn/2022/08/12/world/betelgeuse-star-recovery-scn/index.html
That's a serious ejection.  I hope my Starlink is hardened against that.
I wonder if that figure is correct, I don’t always trust mainstream sources to get figures like that correct?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/18/2022 07:08 am
Initial dating evidence shows it maybe around the same age of Chicxulub, plus or minus a million years. So they might be related.

Quote
An asteroid from space slammed into the Earth's surface 66 million years ago, leaving a massive crater underneath the sea and wreaking havoc with the planet.

No, it's not that asteroid, the one that doomed the dinosaurs to extinction, but a previously unknown crater 248 miles off the coast of West Africa that was created right around the same time. Further study of the Nadir crater, as it's called, could shake up what we know about that cataclysmic moment in natural history.
Uisdean Nicholson, an assistant professor at Heriot-Watt University in Edinburgh, happened on the crater by accident -- he was reviewing seismic survey data for another project on the tectonic split between South America and Africa and found evidence of the crater beneath 400 meters of seabed sediment.
"While interpreting the data, I (came) across this very unusual crater-like feature, unlike anything I had ever seen before," he said.

https://edition.cnn.com/2022/08/17/africa/asteroid-crater-west-africa-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/18/2022 04:48 pm
The discovery of the 528.6 Hz accreting millisecond X-ray pulsar MAXI J1816-195

We present the discovery of 528.6 Hz pulsations in the new X-ray transient MAXI J1816-195. Using NICER, we observed the first recorded transient outburst from the neutron star low-mass X-ray binary MAXI J1816-195 over a period of 28 days. From a timing analysis of the 528.6 Hz pulsations, we find that the binary system is well described as a circular orbit with an orbital period of 4.8 hours and a projected semi-major axis of 0.26 light-seconds for the pulsar, which constrains the mass of the donor star to 0.10−0.55M⊙. Additionally, we observed 15 thermonuclear X-ray bursts showing a gradual evolution in morphology over time, and a recurrence time as short as 1.4 hours. We did not detect evidence for photospheric radius expansion, placing an upper limit on the source distance of 8.6 kpc.

https://arxiv.org/abs/2208.04721
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/18/2022 06:04 pm
Black Hole ‘delivery system’ studied using Chandra and Hubble:

https://youtu.be/RJYAC9g7Lj4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/25/2022 10:58 am
Discovery Alert: Intriguing New ‘Super-Earth' Could Get a Closer Look

The discovery: Planet TOI-1452 b.

Key facts: Using observations from NASA’s Transiting Exoplanet Survey Satellite (TESS), backed up by ground-based telescopes, an international team led by the University of Montreal announced the discovery of a “super-Earth” – a planet that is potentially rocky like ours, but larger – orbiting a red-dwarf star about 100 light-years away. Further investigation could shed light on an intriguing possibility: that the planet might be a “water world.”

Details: Ocean planets are long imagined but difficult to confirm, and TOI-1452 b is no different. About 70% larger than Earth, and roughly five times as massive, its density could be consistent with having a very deep ocean. But more follow-up will be needed. The planet also might be a huge rock, with little or no atmosphere. It could even be a rocky planet with an atmosphere of hydrogen and helium.

If TOI-1452 b were shown to be an ocean world, that ocean could be quite deep indeed. While Earth’s surface is 70% water, our sea of blue makes up less than 1% of Earth’s mass. One simulation of TOI-1452 b, created by computer modeling specialists on the discovery team, showed that water could make up as much as 30% of its mass. That proportion is comparable to watery moons in our solar system – Jupiter’s Ganymede and Callisto, or Saturn’s Titan and Enceladus – believed to hide deep oceans under shells of ice.

TOI-1452 b makes a complete orbit of its star every 11 days – a “year” on TOI-1452 b. But because the red-dwarf star is smaller and cooler than our Sun, the planet receives a similar amount of light from its star as Venus does from our Sun. Liquid water might exist on the planet’s surface, despite its close orbit. The star, by the way, is one of a pair; its gravitational partner also is a red dwarf, estimated to be in a 1,400-year orbit.

Fun facts: Planet TOI-1452 b seems perfectly positioned for further investigation by the James Webb Space Telescope, now delivering science observations from its perch about a million miles (1.6 million kilometers) from Earth. The planet’s distance of 100 light-years is, in astronomical terms, fairly close. Its relatively bright star should allow Webb to capture a spectrum of starlight shining through its atmosphere, a kind of fingerprint of atmospheric components. It also appears in a part of the sky, in the constellation Draco, that Webb can observe almost any time of year. Researchers on the discovery team say they will seek to schedule time on Webb to take a closer look.

The discoverers: The international team that found the planet was led by Charles Cadieux, a Ph.D. student at the University of Montreal. Read the University’s press release. http://www.exoplanetes.umontreal.ca/an-extrasolar-world-covered-in-water/?lang=en

https://exoplanets.nasa.gov/news/1710/discovery-alert-intriguing-new-super-earth-could-get-a-closer-look/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/25/2022 02:15 pm
TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf

We present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright (T=8.5 mag), high proper motion (∼200 mas yr−1), low metallicity ([Fe/H]≈−0.28) K-dwarf with a mass of 0.68±0.05 M⊙ and a radius of 0.67±0.01 R⊙. We obtain photometric follow-up observations with a variety of facilities, and we use these data-sets to determine that the inner planet, TOI-836 b, is a 1.70±0.07 R⊕ super-Earth in a 3.82 day orbit, placing it directly within the so-called 'radius valley'. The outer planet, TOI-836 c, is a 2.59±0.09 R⊕ mini-Neptune in an 8.60 day orbit. Radial velocity measurements reveal that TOI-836 b has a mass of 4.5±0.9 M⊕ , while TOI-836 c has a mass of 9.6±2.6 M⊕. Photometric observations show Transit Timing Variations (TTVs) on the order of 20 minutes for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.

https://arxiv.org/abs/2208.07328
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/31/2022 08:44 pm
Detection of new pulsars at the frequency 111 MHz

The pulsar search was started at the radio telescope LPA LPI at the frequency 111~MHz. The first results deals of a search for right ascension 0h−24h and declinations +21∘−+42∘ are presented in paper. The data with sampling 100 ms and with 6 frequency channals was used. It were found 34 pulsars. Seventeen of them previously been observed at radio telescope LPA LPI, and ten known pulsars has not previously been observed. It were found 7 new pulsars.

https://arxiv.org/abs/2208.08839
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/10/2022 03:44 pm
SPECULOOS discovers a potentially habitable super-Earth

Quote
An international team of scientists, led by Laetitia Delrez, astrophysicist at the University of Liège, has just announced the discovery of two 'super-Earth' type planets orbiting LP 890-9.  Also known as TOI-4306 or SPECULOOS-2, this small, cool star located about 100 light-years from our Earth is the second coolest star around which planets have been detected, after the famous TRAPPIST-1. This important discovery is published in the journal Astronomy &amp; Astrophysics.

https://www.news.uliege.be/cms/c_16795199/en/speculoos-discovers-a-potentially-habitable-super-earth

Related paper:

https://www.aanda.org/component/article?access=doi&amp;doi=10.1051/0004-6361/202244041
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/16/2022 03:28 pm
We’ve Finally Figured Out Why Saturn Is ‘Lord Of The Rings,’ Say Scientists

Quote
A new paper published in the journal Science this week claimed that Saturn’s rings are the result of a moon that was torn apart by the planet’s tidal forces about 160 million years ago. Since the planet is about the same age as the solar system—so about 4.5 billion years old—that's the blink of an eye.

The new theory also inextricably links the formation of Saturn’s rings to how the planet got its axial tilt.

“The tilt is too large to be a result of known formation processes in a protoplanetary disk or from later, large collisions,” said Jack Wisdom, a professor of planetary science at the Massachusetts Institute of Technology (MIT). “A variety of explanations have been offered, but none is totally convincing. The cool thing is that the previously unexplained young age of the rings is naturally explained in our scenario.”

https://www.forbes.com/sites/jamiecartereurope/2022/09/16/weve-finally-figured-out-why-saturn-is-lord-of-the-rings-say-scientists/

How Saturn got its tilt and its rings

Abstract

The angle between a planet’s equator and its orbit plane is known as its axial tilt or obliquity. As gas giants form from the disk made of gas and dust that swirls around the host star, the gas accretion process is expected to conserve the angular momentum and force the planet to spin perpendicular to its orbital plane. However, within our own Solar System, all gas giants, except for Jupiter, have a substantial nonzero tilt. This implies that something else must have happened to these planets after they formed that caused them to tilt. On page 1285 of this issue, Wisdom et al. (1) describe a model that can explain the origin of Saturn’s obliquity. Its tilt may have been caused by a process involving Saturn’s wobbling tilt (i.e., spin-axis precession), Neptune’s wobbling orbit (i.e., nodal precession), the elimination of a hypothetical satellite, and the outward migration of Titan—the largest moon of Saturn.

https://www.science.org/doi/10.1126/science.abq3184
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/17/2022 04:44 pm
Quote
The meteorite crashed into a driveway in the Gloucestershire town of Winchcombe last February and is believed to hold clues about where the water in the Earth's vast oceans came from.

Some 12% of the sample was made up of water, and offers a lot of insights since it was the least contaminated specimen to be collected, according to Ashley King, a researcher in the planetary materials group at the Natural History Museum.

"The composition of that water is very, very similar to the composition of water in the Earth's oceans," he told the British Science Festival.

"It's a really good piece of evidence that asteroids and bodies like Winchcombe made a very important contribution to the Earth's oceans."

Quote
Dr King continued: "We've had a hint that some asteroids match back nicely to the Earth.

"But now we have a meteorite which is really fresh that we know hasn't been modified, and it's confirming that same story."

Speaking at De Montfort University, which is hosting the festival, Dr King revealed that analysis suggests that the meteorite derived from an asteroid somewhere near Jupiter.

It is believed to have been formed around 4.6 billion years ago and has taken some 300,000 years to reach Earth.

https://news.sky.com/story/extra-terrestrial-water-found-for-first-time-in-meteorite-that-landed-in-uk-12699481
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/22/2022 11:14 am
Astronomers unveil new—and puzzling—features of mysterious fast radio bursts

Quote
What makes the latest observations surprising to scientists is the irregular, short-time variations of the so-called "Faraday rotation measure", which is the strength of the magnetic field and density of particles in the vicinity of the FRB source. The variations went up and down during the first 36 days of observation and suddenly stopped during the last 18 days before the source quenched.

"I equate it to filming a movie of the surroundings of an FRB source, and our film revealed a complex, dynamically evolving, magnetized environment that was never imagined before," said Zhang. "Such an environment is not straightforwardly expected for an isolated magnetar. Something else might be in the vicinity of the FRB engine, possibly a binary companion," added Zhang.

https://phys.org/news/2022-09-astronomers-unveil-newand-puzzlingfeatures-mysterious.html

Here’s the related paper:

A fast radio burst source at a complex magnetized site in a barred galaxy

Abstract
Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts1,2,3. Recent observations of a Galactic FRB4,5,6,7,8 suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref. 9). These observations show irregular short-time variation of the Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (AU; Earth–Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy10,11,12 show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.

https://www.nature.com/articles/s41586-022-05071-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/22/2022 01:41 pm
Hot Gas Swirling Around our Supermassive Black Hole (ESOcast 256 Light)

https://youtu.be/QesRBaLM6No
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/29/2022 07:14 pm
New study 'gives best indication yet' that there is liquid water on Mars

Quote
British scientists say they have found evidence which "gives the best indication yet that there is liquid water on Mars".

Their study is the first independent lead using data, apart from radar, that such water lies beneath the red planet's south polar ice cap.

But the experts have also cautioned that it "does not necessarily mean that life exists on Mars".

https://news.sky.com/story/amp/mars-new-study-gives-best-indication-yet-that-there-is-liquid-water-on-red-planet-12707625
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/09/2022 06:48 pm
Quote
A diamond recently unearthed in a diamond mine in Botswana is just such a stone. It's riddled with flaws containing traces of ringwoodite, ferropericlase, enstatite, and other minerals that suggest the diamond formed 660 kilometers (410 miles) below Earth's surface.

Moreover, they suggest that the environment in which they formed – a divide between the upper and lower mantle called the 660-kilometer discontinuity (or, more simply, the transition zone) – is rich in water.

"The occurrence of ringwoodite together with the hydrous phases indicate a wet environment at this boundary," write a team of researchers led by mineral physicist Tingting Gu of the Gemological Institute of New York and Purdue University.

https://www.sciencealert.com/diamond-from-660-kilometers-below-earths-surface-reveals-a-water-rich-environment/amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/10/2022 06:21 pm
Strange Ripples Have Been Detected at The Edge of The Solar System

Quote
The bubble of space encasing the Solar System might be wrinkled, at least sometimes.

Data from a spacecraft orbiting Earth has revealed ripple structures in the termination shock and heliopause: shifting regions of space that mark one of the boundaries between the space inside the Solar System, and what's outside – interstellar space.

https://www.sciencealert.com/strange-ripples-have-been-detected-at-the-edge-of-the-solar-system
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/12/2022 04:33 pm
Quote
The Earth is subjected to a hail of subatomic particles from the Sun and beyond our solar system which could be the cause of glitches that afflict our phones and computers. And the risk is growing as microchip technology shrinks.

https://www.bbc.com/future/article/20221011-how-space-weather-causes-computer-errors
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/13/2022 10:42 am
I am guessing this could be a hypernova candidate.

Scientists Just Detected a Colossal Gamma-Ray Burst, And It's a Record-Breaker

Quote
Observatories around the world have just detected a colossal flare of extremely energetic radiation described as "record-breaking".

The event, first detected on October 9, was so bright that it was initially confused for an event closer to home. Initially dubbed Swift J1913.1+1946, it was thought to be a brief flash of X-rays from a not-too-distant source. It was only through further analysis that astronomers discovered the true nature of the glow – a gamma-ray burst, one of the most violent explosions in the Universe, now re-named GRB221009A.

Though further away, it was still one of the closest seen yet, just 2.4 billion light-years away. Moreover, this exceptionally bright gamma-ray burst appears to be the most energetic ever detected, coming in at up to 18 teraelectronvolts.

Quote
It's unclear, yet, what we're looking at with GRB221009A.

"It is still too early to tell," Anderson says. "The light from an underlying supernova will take days to brighten. However, given this gamma ray burst's long duration, it may be a very powerful type of supernova."

Quote
What we do know is that the burst appears to have emerged from a very dusty galaxy, and that it was very powerful. And the Large High Altitude Air Shower Observatory (LHAASO), a Cherenkov observatory in China, has detected photons with energies up to roughly 18 teraelectronvolts (TeV). To date, just a handful of gamma-ray bursts have been detected with emission in the TeV range; if the LHAASO data is verified, GRB221009A will be the first above 10 TeV.

https://www.sciencealert.com/scientists-just-detected-a-colossal-gamma-ray-burst-and-its-a-record-breaker
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/13/2022 12:39 pm
Heaviest Element (Barium) yet Detected in an Exoplanet Atmosphere (ESOCast 257 Light):

https://youtu.be/2IUT_P1LU-Y 
Title: Re: Astronomy & Planetary Science Thread
Post by: sghill on 10/17/2022 05:52 pm

https://mashable.com/article/supermassive-black-hole-delayed-emission

Quote
"A black hole is burping up the remains of a star that it shredded and consumed nearly 3 years ago. “This caught us completely by surprise — no one has ever seen anything like this before," says astronomer Yvette Cendes."

I wonder if the ejected material, which is moving at nearly 50% the speed of light, is experiencing time dilation, and we are seeing three years later an event that took place in mere moments from the perspective of the debris.
Title: Re: Astronomy & Planetary Science Thread
Post by: Nomadd on 10/17/2022 06:05 pm

https://mashable.com/article/supermassive-black-hole-delayed-emission
I wonder if the ejected material, which is moving at nearly 50% the speed of light, is experiencing time dilation, and we are seeing three years later an event that took place in mere moments from the perspective of the debris.

 About a 13% difference at .5C.

https://www.emc2-explained.info/Time-Dilation-at-Low-Speeds/#.Y02Z9qROkzZ
Title: Re: Astronomy & Planetary Science Thread
Post by: DanClemmensen on 10/17/2022 06:12 pm

https://mashable.com/article/supermassive-black-hole-delayed-emission

Quote
"A black hole is burping up the remains of a star that it shredded and consumed nearly 3 years ago. “This caught us completely by surprise — no one has ever seen anything like this before," says astronomer Yvette Cendes."

I wonder if the ejected material, which is moving at nearly 50% the speed of light, is experiencing time dilation, and we are seeing three years later an event that took place in mere moments from the perspective of the debris.

 About a 13% difference at .5C.
General relativity (gravity effects) would dominate over special relativity (velocity effects), I think.
Title: Re: Astronomy & Planetary Science Thread
Post by: sghill on 10/17/2022 06:28 pm

https://mashable.com/article/supermassive-black-hole-delayed-emission
I wonder if the ejected material, which is moving at nearly 50% the speed of light, is experiencing time dilation, and we are seeing three years later an event that took place in mere moments from the perspective of the debris.

 About a 13% difference at .5C.

https://www.emc2-explained.info/Time-Dilation-at-Low-Speeds/#.Y02Z9qROkzZ

Thanks!

I was thinking along the lines that the material sped up to nearly 1C on its way towards the event horizon, but came in at a tangential, so it didn't fall in, yet time dilation still got pretty high. It is now emerging three years later but slowed down to .5C because of the extreme gravity deaccelerating it on its way back out.

The article said we've never seen stuff moving this fast.

Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/20/2022 11:18 pm
This latest study makes the discrepancy between the two measurements even more significant. Also that two thirds of the universe is just dark energy, the other third is dark matter with then some matter.

Quote
Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is composed of about two-thirds dark energy and one-third matter — mostly in the form of dark matter — and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

Quote
Taking the data as a whole, the new analysis holds that 66.2 percent of the universe manifests as dark energy, with the remaining 33.8 percent being a combination of dark matter and matter.

https://news.harvard.edu/gazette/story/2022/10/most-precise-accounting-yet-of-dark-matter-and-dark-energy/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/21/2022 04:14 pm
A new paper suggests that looking for life on planets orbiting M dwarfs maybe a case of barking up the wrong tree. As their study shows that the planet studied has no significant atmosphere.

GJ 1252b: A Hot Terrestrial Super-Earth with No Atmosphere

Abstract
In recent years, the discovery of increasing numbers of rocky, terrestrial exoplanets orbiting nearby stars has drawn increased attention to the possibility of studying these planets' atmospheric and surface properties. This is especially true for planets orbiting M dwarfs, whose properties can best be studied with existing observatories. In particular, the minerological composition of these planets and the extent to which they can retain their atmospheres in the face of intense stellar irradiation both remain unresolved. Here, we report the detection of the secondary eclipse of the terrestrial exoplanet GJ 1252b, obtained via 10 eclipse observations using the Spitzer Space Telescope's IRAC2 4.5 μm channel. We measure an eclipse depth of ${149}_{-32}^{+25}$ ppm, corresponding to a dayside brightness temperature of ${1410}_{-125}^{+91}$ K. This measurement is consistent with the prediction for a bare rock surface. Comparing the eclipse measurement to a large suite of simulated planetary spectra indicates that GJ 1252b has a surface pressure of 10 bar, i.e., substantially thinner than the atmosphere of Venus. Assuming energy-limited escape, even a 100 bar atmosphere would be lost in &lt;1 Myr, far shorter than our gyrochronological age estimate of 3.9 ± 0.4 Gyr. The expected mass loss could be overcome by mantle outgassing, but only if the mantle's carbon content were &gt;7% by mass—over two orders of magnitude greater than that found in Earth. We therefore conclude that GJ 1252b has no significant atmosphere. Model spectra with granitoid or feldspathic surface composition, but with no atmosphere, are disfavored at &gt;2σ. The eclipse occurs just +1.4${}_{-1.0}^{+2.8}$ minutes after orbital phase 0.5, indicating $e\cos \omega $ = +0.0025 ${}_{-0.0018}^{+0.0049}$, consistent with a circular orbit. Tidal heating is therefore likely to be negligible with regard to GJ 1252b's global energy budget. Finally, we also analyze additional, unpublished TESS transit photometry of GJ 1252b, which improves the precision of the transit ephemeris by a factor of 10, provides a more precise planetary radius of 1.180 ± 0.078 R⊕, and rules out any transit-timing variations with amplitudes 1 minute.

https://iopscience.iop.org/article/10.3847/2041-8213/ac886b
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 10/21/2022 09:02 pm
A new paper suggests that looking for life on planets orbiting M dwarfs maybe a case of barking up the wrong tree. As their study shows that the planet studied has no significant atmosphere.

I think that's a strong conclusion to be drawn just from looking at one planet!

GJ 1252b has a day temperature of 1400 K, so was hardly a promising candidate for life in any event.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/26/2022 11:22 am
Modelling cosmic radiation events in the tree-ring radiocarbon record

Qingyuan Zhang , Utkarsh Sharma , Jordan A. Dennis , Andrea Scifo , Margot Kuitems , Ulf Büntgen , Mathew J. Owens , Michael W. Dee  and Benjamin J. S. Pope
Published:26 October 2022https://doi.org/10.1098/rspa.2022.0497

Abstract

Annually resolved measurements of the radiocarbon content in tree-rings have revealed rare sharp rises in carbon-14 production. These ‘Miyake events’ are likely produced by rare increases in cosmic radiation from the Sun or other energetic astrophysical sources. The radiocarbon produced is not only circulated through the Earth’s atmosphere and oceans, but also absorbed by the biosphere and locked in the annual growth rings of trees. To interpret high-resolution tree-ring radiocarbon measurements therefore necessitates modelling the entire global carbon cycle. Here, we introduce ‘ticktack’ (https://github.com/SharmaLlama/ticktack/), the first open-source Python package that connects box models of the carbon cycle with modern Bayesian inference tools. We use this to analyse all public annual  14C
 tree data, and infer posterior parameters for all six known Miyake events. They do not show a consistent relationship to the solar cycle, and several display extended durations that challenge either astrophysical or geophysical models.

https://royalsocietypublishing.org/doi/10.1098/rspa.2022.0497
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/26/2022 02:34 pm
Long-term Photometric Study of the Pre-main Sequence Star V1180 Cas

In this paper results from the optical photometric observations of the pre-main-sequence star V1180 Cas are reported. The star is a young variable associated with the dark cloud Lynds 1340, located at a distance of 600 pc from the Sun in the star forming region in Cassiopeia. V1180 Cas shows a large amplitude variability interpreted as a combination of accretion-induced and extinction-driven effects. Our data from VRI CCD photometric observations of the star are collected from September 2011 to February 2022. During our monitoring, we recorded several brightness dips with large amplitudes of up to 5 mag. (I-band). At the same time, increases in brightness over periods of several weeks have also been recorded. In this paper, we compare the photometric data obtained for V1180 Cas with observations of other low-mass pre-main sequence objects.

https://arxiv.org/abs/2210.09660#
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/31/2022 04:16 pm
Fly through a dead star’s ‘ghost’ for Halloween:

https://youtu.be/hADIiD6I1z0
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/02/2022 08:14 am
L 363-38 b: a planet newly discovered with ESPRESSO orbiting a nearby M dwarf star

Context. Planets around stars in the solar neighbourhood will be prime targets for characterisation with upcoming large space- and ground-based facilities. Since large-scale exoplanet searches will not be feasible with such telescopes, it is crucial to use currently available data and instruments to find possible target planets before next generation facilities come online.
Aims. We aim at detecting new extrasolar planets around stars in the solar neighbourhood by blind radial velocity (RV) search with ESPRESSO. Our target sample consist of nearby stars (d < 11 pc) with little (< 10) or no previous RV measurements.
Methods. We use 31 radial velocity measurements obtained with ESPRESSO at the VLT between December 2020 and February 2022 of the nearby M dwarf star (M_star = 0.21 M_sun, d = 10.23 pc) L 363-38 to derive the orbital parameters of the newly discovered planet. In addition, we use TESS photometry and archival VLT/NaCo high contrast imaging data to put further constraints on the orbit inclination and the possible planetary system architecture around L 363-38.
Results. We present the detection of a new extrasolar planet orbiting the nearby M dwarf star L 363-38. L 363-38 b is a planet with minimum mass mp sin(i) = 4.67+/-0.43 M_Earth orbiting its star with a period P = 8.781+/-0.007 d, corresponding to a semi-major axis a = 0.048+/-0.006 AU, which is well inside the inner edge of the habitable zone. We further estimate a minimum radius rp sin(i) = 1.55 - 2.75 R_Earth and an equilibrium temperature Teq = 330K.

https://arxiv.org/abs/2210.12710
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/03/2022 07:23 pm
Quote
Scientists have found a vast “extragalactic structure” hidden behind the Milky Way.

The structure has been hidden because it is in the so-called “zone of avoidance”. That is the part of space that is hidden by the “bulge” of our own galaxy, and so means it has been little explored.

The zone, which is also called the zone of galactic obscuration, happens because the dust and stars of our own Milky Way get in the way of its light as it makes its way to Earth. It means that some 10 per cent of the sky remains largely mysterious, hidden behind our own galaxy.

https://www.independent.co.uk/tech/milky-way-structure-galaxy-nasa-b2217054.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Mongo62 on 11/03/2022 07:51 pm
This latest study makes the discrepancy between the two measurements even more significant. Also that two thirds of the universe is just dark energy, the other third is dark matter with then some matter.

Quote
Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is composed of about two-thirds dark energy and one-third matter — mostly in the form of dark matter — and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

Quote
Taking the data as a whole, the new analysis holds that 66.2 percent of the universe manifests as dark energy, with the remaining 33.8 percent being a combination of dark matter and matter.

https://news.harvard.edu/gazette/story/2022/10/most-precise-accounting-yet-of-dark-matter-and-dark-energy/

On the other hand, Sabine Hossenfelder's latest video talks about evidence AGAINST the existence of "Dark Matter", and for MOND.

Sabine is a very grounded person, resistant to flights of fancy, but also willing to look at new evidence, so I am inclined to take whatever she says seriously.

New Evidence Against Dark Matter, Carbon Footprint Of Higgs Bosons, Data Transmission Record & more (https://www.youtube.com/watch?v=lVkyUpMDeUs)

https://www.youtube.com/watch?v=lVkyUpMDeUs
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 11/04/2022 01:43 pm
This latest study makes the discrepancy between the two measurements even more significant. Also that two thirds of the universe is just dark energy, the other third is dark matter with then some matter.

Quote
Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is composed of about two-thirds dark energy and one-third matter — mostly in the form of dark matter — and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

Quote
Taking the data as a whole, the new analysis holds that 66.2 percent of the universe manifests as dark energy, with the remaining 33.8 percent being a combination of dark matter and matter.

https://news.harvard.edu/gazette/story/2022/10/most-precise-accounting-yet-of-dark-matter-and-dark-energy/

On the other hand, Sabine Hossenfelder's latest video talks about evidence AGAINST the existence of "Dark Matter", and for MOND.

Sabine is a very grounded person, resistant to flights of fancy, but also willing to look at new evidence, so I am inclined to take whatever she says seriously.

New Evidence Against Dark Matter, Carbon Footprint Of Higgs Bosons, Data Transmission Record & more (https://www.youtube.com/watch?v=lVkyUpMDeUs)

https://www.youtube.com/watch?v=lVkyUpMDeUs
MOND has the basic problem that it ignores half of the problem. It kinda works in very specific cases but totally fails in others.  You cannot replace a theory (how gravity works) unless your theory accounts for EVERYTHING the current theory does. MOND always fails this test.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/05/2022 06:54 am
Talk about looking for a needle in a haystack and even now with the re-analysis it still hasn’t reached 5 sigma significance.

Quote
Don your binoculars for a night of star gazing and you might be able to spot the seemingly innocuous spiral galaxy Messier 77 (M77), a bright but dusty mass of stars that sits 47 million light-years from Earth. Hidden under this dust is a supermassive black hole that is powering intense radiation from the surrounding gas. Now the IceCube Collaboration reports that they have found evidence that this galaxy is also a source of high-energy cosmic neutrinos [1]. Collaboration members say that the finding paves the way to using cosmic neutrinos for astrophysical measurements that could help solve the origin of cosmic rays, the Universe’s highest-energy particles, and help solve mysteries about cosmic rays and dark matter.

https://physics.aps.org/articles/v15/171

Here’s the related paper:

https://www.science.org/doi/10.1126/science.abg3395
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/07/2022 04:05 pm
A powerful (and likely young) radio-loud quasar at z=5.3

We present the discovery of PSO J191.05696+86.43172 (hereafter PSO J191+86), a new powerful radio-loud quasar (QSO) in the early Universe (z = 5.32). We discovered it by cross-matching the NRAO VLA Sky Survey (NVSS) radio catalog at 1.4 GHz with the first data release of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS PS1) in the optical. With a NVSS flux density of 74.2 mJy, PSO J191+86 is one of the brightest radio QSO discovered at z∼5. The intensity of its radio emission is also confirmed by the very high value of radio loudness (R>300). The observed radio spectrum of PSO J191+86 shows a possible turnover around ∼1 GHz (i.e., ∼6 GHz in the rest frame), making it a Gigahertz-Peaked Spectrum (GPS) source. However, variability could affect the real shape of the radio spectrum, since the data in hand have been taken ∼25 years apart. By assuming a peak of the observed radio spectrum between 1 and 2 GHz (i.e. ∼ 6 and 13 GHz in the rest-frame) we found a linear size of the source of ∼10-30 pc and a corresponding kinetic age of 150-460 yr. This would make PSO J191+86 a newly born radio source. However, the large X-ray luminosity (5.3×1045 erg s−1), the flat X-ray photon index (ΓX=1.32) and the optical-X-ray spectral index (αox~=1.329) are typical of blazars. This could indicate that the non-thermal emission of PSO J191+86 is Doppler boosted. Further radio observations (both on arcsec and parsec scales) are necessary to better investigate the nature of this powerful radio QSO.

https://arxiv.org/abs/2210.14946
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/08/2022 02:42 pm
The GMRT High Resolution Southern Sky Survey for pulsars and transients − IV: Discovery of 4 new pulsars with an FFA search

The fast Fourier transform (FFT) based periodicity search methods provide an efficient way to search for millisecond and binary pulsars but encounter significant sensitivity degradation while searching for long period and short duty cycle pulsars. An alternative to FFT-based search methods called the Fast Folding Algorithm (FFA) search, provides superior sensitivity to search for signals with long periods and short duty cycles. In the GMRT High Resolution Southern Sky (GHRSS) survey, we are using an FFA-based pipeline to search for isolated pulsars in a period range of 100 ms to 100 s. We have processed 2800 degree2 of the sky coverage away from the Galactic plane and discovered 6 new pulsars. Here, we report the discovery of 4 of these pulsars with the FFA search pipeline. This includes a narrow duty cycle pulsar, J1936−30, which shows nulling behavior with an extreme nulling fraction of ∼90%. Two of the GHRSS discoveries from the FFA search lie in narrow duty cycle ranges beyond the limit of the existing population. The implementation of FFA search in the GHRSS survey and other pulsar surveys is expected to recover the missing population of long period and short duty cycle pulsars.

https://arxiv.org/abs/2210.16650
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/08/2022 02:46 pm
This story has now turned up in some UK media but has already been debunked by Scott Manley.

https://youtu.be/8vmOngK18xg
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/09/2022 02:16 pm
Photometric properties and stellar parameters of the rapidly rotating magnetic early-B star HD 345439

We first present the multicolor photometry results of the rapidly rotating magnetic star HD 345439 using the Nanshan One-meter Wide-field Telescope. From the photometric observations, we derive a rotational period of 0.7699\pm0.0014 day. The light curves of HD 345439 are dominated by the double asymmetric S-wave feature that arises from the magnetic clouds. Pulsating behaviors are not observed in Sector 41 of the Transiting Exoplanet Survey Satellite. No evidence is found of the occurrence of centrifugal breakout events neither in the residual flux nor in the systematic variations at the extremum of the light curve. Based on the hypothesis of the Rigidly Rotating Magnetosphere model, we restrict the magnetic obliquity angle {β} and the rotational inclination angle i so that they satisfy the approximate relation {β+i≈105}. The colour excess, extinction, and luminosity are determined to be E(B−V)=0.745±0.016mag, AV=2.31±0.05mag, and log(L/L)=3.82±0.1dex, respectively. Furthermore, we derive the effective temperature as Teff=22±1kK and the surface gravity as logg=4.00±0.22. The massM=7.24+1.75−1.24M, radiusR=4.44+2.68−1.93R, and ageτage=23.62+4.24−21.97Myr are estimated from the Hertzsprung--Russell Diagram

https://arxiv.org/abs/2211.00271#
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/10/2022 04:52 pm
Near of course being a relative term here.

A Sun-like star orbiting a black hole

Abstract
We report discovery of a bright, nearby (G=13.8;d=480pc
) Sun-like star orbiting a dark object. We identified the system as a black hole candidate via its astrometric orbital solution from the Gaia mission. Radial velocities validated and refined the Gaia solution, and spectroscopy ruled out significant light contributions from another star. Joint modeling of radial velocities and astrometry constrains the companion mass to M2 = 9.62 ± 0.18 M. The spectroscopic orbit alone sets a minimum companion mass of M2 &gt; 5 M; if the companion were a 5 M star, it would be 500 times more luminous than the entire system. These constraints are insensitive to the mass of the luminous star, which appears as a slowly-rotating G dwarf (Teff=5850K
, log g = 4.5, M = 0.93 M), with near-solar metallicity ([Fe/H]=−0.2
) and an unremarkable abundance pattern. We find no plausible astrophysical scenario that can explain the orbit and does not involve a black hole. The orbital period, Porb = 185.6 days, is longer than that of any known stellar-mass black hole binary. The system’s modest eccentricity (e = 0.45), high metallicity, and thin-disk Galactic orbit suggest that it was born in the Milky Way disk with at most a weak natal kick. How the system formed is uncertain. Common envelope evolution can only produce the system’s wide orbit under extreme and likely unphysical assumptions. Formation models involving triples or dynamical assembly in an open cluster may be more promising. This is the nearest known black hole by a factor of 3, and its discovery suggests the existence of a sizable population of dormant black holes in binaries. Future Gaia releases will likely facilitate the discovery of dozens more.

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stac3140/6794289
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2022 11:19 am
Spectral analysis of ultra-cool white dwarfs polluted by planetary debris

ABSTRACT
We identify two ultra-cool (Teff&lt;4000
Teff&lt;4000K) metal-polluted (DZ) white dwarfs WD J2147−4035 and WD J1922+0233 as the coolest and second coolest DZ stars known to date with Teff≈3050 Teff≈3050K and Teff≈3340 Teff ≈3340K, respectively. Strong atmospheric collision-induced absorption (CIA) causes the suppression of red optical and infrared flux in WD J1922+0233, resulting in an unusually blue colour given its low temperature. WD J2147−4035 has moderate infrared CIA yet has the reddest optical colours known for a DZ white dwarf. Microphysics improvements to the non-ideal effects and CIA opacities in our model atmosphere code yields reasonable solutions to observations of these ultra-cool stars. WD J2147−4035 has a cooling age of over 10 Gyr which is the largest known for a DZ white dwarf, whereas WD J1922+0233 is slightly younger with a cooling age of 9 Gyr. Galactic kinematics calculations from precise Gaia EDR3 astrometry reveal these ultra-cool DZ stars as likely members of the Galactic disc thus they could be pivotal objects in future studies constraining an upper age limit for the disc of the Milky Way. We present intermediate-resolution spectroscopy for both objects, which provides the first spectroscopic observations of WD J2147−4035. Detections of sodium and potassium are made in both white dwarfs, in addition to calcium in WD J1922+0233 and lithium in WD J2147−4035. We identify the magnetic nature of WD J2147−4035 from Zeeman splitting in the lithium line and also make a tentative detection of carbon, so we classify this star as DZQH. WD J1922+0233 likely accreted planetary crust debris, while the debris composition that polluted WD J2147−4035 remains unconstrained.

https://academic.oup.com/mnras/article-abstract/517/3/4557/6795240
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2022 04:03 pm
Shock cooling of a red-supergiant supernova at redshift 3 in lensed images

Abstract
The core-collapse supernova of a massive star rapidly brightens when a shock, produced following the collapse of its core, reaches the stellar surface. As the shock-heated star subsequently expands and cools, its early-time light curve should have a simple dependence on the size of the progenitor1 and therefore final evolutionary state. Measurements of the radius of the progenitor from early light curves exist for only a small sample of nearby supernovae2,3,4,5,6,7,8,9,10,11,12,13,14, and almost all lack constraining ultraviolet observations within a day of explosion. The several-day time delays and magnifying ability of galaxy-scale gravitational lenses, however, should provide a powerful tool for measuring the early light curves of distant supernovae, and thereby studying massive stellar populations at high redshift. Here we analyse individual rest-frame exposures in the ultraviolet to the optical taken with the Hubble Space Telescope, which simultaneously capture, in three separate gravitationally lensed images, the early phases of a supernova at redshift z ≈ 3 beginning within 5.8 ± 3.1 hours of explosion. The supernova, seen at a lookback time of approximately 11.5 billion years, is strongly lensed by an early-type galaxy in the Abell 370 cluster. We constrain the pre-explosion radius to be 533+154−119533-119+154 solar radii, consistent with a red supergiant. Highly confined and massive circumstellar material at the same radius can also reproduce the light curve, but because no similar low-redshift examples are known, this is unlikely.

https://www.nature.com/articles/s41586-022-05252-5
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/14/2022 04:14 pm
Rapid formation of exoplanetesimals revealed by white dwarfs

Abstract
The timing of formation of the first planetesimals determines the mode of planetary accretion and their geophysical and compositional evolution. Astronomical observations of circumstellar disks and Solar System geochronology provide evidence for planetesimal formation during molecular cloud collapse, much earlier than previously estimated. Here we present distinct observational evidence from white dwarf planetary systems for planetesimal formation occurring during the first few hundred thousand years after cloud collapse in exoplanetary systems. A substantial fraction of white dwarfs have accreted planetary material rich in iron core or mantle material. For the exo-asteroids accreted by white dwarfs to form iron cores, substantial heating is required. By simulating planetesimal evolution and collisional evolution, we show that the most likely heat source is short-lived radioactive nuclides such as 26Al (which has a half-life of ~0.7 Myr). Core-rich materials in the atmospheres of white dwarfs, therefore, provide independent evidence for rapid planetesimal formation, concurrent with star formation.

https://www.nature.com/articles/s41550-022-01815-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/14/2022 04:19 pm
Supermassive Black Hole and Broad-line Region in NGC 5548: Results from Five-season Reverberation Mapping

Abstract
NGC 5548 is one of the active galactic nuclei (AGNs) selected for our long-term spectroscopic monitoring with the Lijiang 2.4 m telescope, aiming at investigating the origin and evolution of broad-line regions (BLRs), accurately measuring the mass of supermassive black holes (SMBHs), and understanding the structure and evolution of the AGN. We have performed five-season observations for NGC 5548 with the median sampling interval ranging from 1.25 to 3 days. The light curves of the 5100 Å continuum and broad emission lines are measured after subtracting contamination of the host galaxy starlight. The time lags of the broad He ii, He i, Hγ, and Hβ lines with respect to the 5100 Å continuum are obtained for each season and their mean time lags over the five seasons are 0.69, 4.66, 4.60, and 8.43 days, respectively. The Hγ and Hβ velocity-resolved lag profiles in the seasons of 2015, 2018, 2019, and 2021 are constructed, from which an "M-shaped" structure is found in 2015 but disappears after 2018. Our five-season reverberation mapping (RM) yields an average virial SMBH mass of M•/107 M⊙ = 14.22, with a small standard deviation of 1.89. By combining the previous 18 RM campaigns and our five-season campaign for NGC 5548, we find that there exists a time lag of 3.5 yr between the changes in the BLR size and optical luminosity. In addition, we construct the BLR radius−luminosity relation and the virial relation for NGC 5548.

https://iopscience.iop.org/article/10.3847/1538-4365/ac94d3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/14/2022 04:28 pm
Origin of highly r-process-enhanced stars in a cosmological zoom-in simulation of a Milky Way-like galaxy

ABSTRACT
The r-process-enhanced (RPE) stars provide fossil records of the assembly history of the Milky Way (MW) and the nucleosynthesis of the heaviest elements. Observations by the R-Process Alliance (RPA) and others have confirmed that many RPE stars are associated with chemo-dynamically tagged groups, which likely came from accreted dwarf galaxies of the MW. However, we do not know how RPE stars are formed. Here, we present the result of a cosmological zoom-in simulation of an MW-like galaxy with r-process enrichment, performed with the highest resolution in both time and mass. Thanks to this advancement, unlike previous simulations, we find that most highly RPE (r-II; [Eu/Fe] &gt; +0.7) stars are formed in low-mass dwarf galaxies that have been enriched in r-process elements for [Fe/H] &lt;−2.5
, while those with higher metallicity are formed in situ, in locally enhanced gas clumps that were not necessarily members of dwarf galaxies. This result suggests that low-mass accreted dwarf galaxies are the main formation site of r-II stars with [Fe/H] &lt;−2.5
. We also find that most low-metallicity r-II stars exhibit halo-like kinematics. Some r-II stars formed in the same halo show low dispersions in [Fe/H] and somewhat larger dispersions of [Eu/Fe], similar to the observations. The fraction of simulated r-II stars is commensurate with observations from the RPA, and the distribution of the predicted [Eu/Fe] for halo r-II stars matches that observed. These results demonstrate that RPE stars can be valuable probes of the accretion of dwarf galaxies in the early stages of their formation.

https://academic.oup.com/mnras/article-abstract/517/4/4856/6808594
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/14/2022 08:44 pm
Imprints of cosmological tensions in reconstructed gravity

Abstract
There has been substantial interest in modifications of the standard Λ cold dark matter (ΛCDM, where Λ is the cosmological constant) cosmological model prompted by tensions between certain datasets, most notably the Hubble tension. The late-time modifications of the ΛCDM model can be parameterized by three time-dependent functions describing the expansion history of the Universe and gravitational effects on light and matter in the large-scale structure. We perform a joint Bayesian reconstruction of these three functions from a combination of recent cosmological observations, utilizing a theory-informed prior built on the general Horndeski class of scalar–tensor theories. This reconstruction is interpreted in light of the well-known Hubble constant, clustering amplitude S8 and lensing amplitude AL tensions. We identify the phenomenological features that alternative theories would need to have to ease some of these tensions, and deduce important constraints on broad classes of modified gravity models. Among other things, our findings suggest that late-time dynamical dark energy and modifications of gravity are not likely to offer a solution to the Hubble tension, or simultaneously solve the AL and S8 tensions.

https://www.nature.com/articles/s41550-022-01808-7
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/17/2022 10:51 am
Quote
A meteorite that crashed on the Gloucestershire town of Winchcombe last year contained water that was a near-perfect match for that on Earth.

Quote
The new analysis also confirms the meteorite's origin.
Camera footage of the fireball has allowed researchers to work out a very precise trajectory.
Calculating backwards, this indicates the meteorite came from the outer asteroid belt between Mars and Jupiter.

https://www.bbc.com/news/science-environment-63631563.amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/18/2022 02:06 pm
The confusion of people when a physicist and actor with the same name meet.

https://www.bbc.co.uk/news/av/entertainment-arts-63674240
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 11/18/2022 03:58 pm
Baikal-GVD, an underwater neutrino detector in the pristine waters of Lake Baikal in Russia in the likes lf KM3Net or IceCube, confirms IceCube's extragalactic neutrino results with its own observations at 3 sigma:

https://arxiv.org/abs/2211.09447
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 11/21/2022 08:25 pm
The Artemis Rocket Launch and Particle Physics
THE LUNAR POLAR HYDROGEN MAPPER (LUNAH-MAP)

Mapping Lunar ice via neutron counting as the cube-sat flies by.

https://profmattstrassler.com/2022/11/21/the-artemis-rocket-launch-and-particle-physics/#more-12937
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/22/2022 04:29 pm
Helium-enhanced planets along the upper edge of the radius valley

Abstract
The Kepler survey revealed that the radius distribution of sub-Neptunes is bimodal: there is a scarcity of planets between 1.5 and 2.0 R⊕. However, the mechanism that creates the valley is unknown. The low mean densities of sub-Neptunes imply that they formed within a few million years and accreted primordial envelopes. Because these planets receive X-ray and UV fluxes comparable to the gravitational binding energy of their envelopes, their atmospheres are susceptible to mass loss. We model the thermal and compositional evolution of sub-Neptunes undergoing escape with diffusive separation between hydrogen and helium and show that preferential loss of hydrogen can change their atmospheric compositions. Planets with radii between 1.6 and 2.5 R⊕ can obtain atmospheric helium mass fractions in excess of 40% from billions of years of photoevaporation. Such enhancement can be detected through transmission spectroscopy, providing a novel observational test to determine whether atmospheric escape creates the radius valley.

https://www.nature.com/articles/s41550-022-01823-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/22/2022 04:34 pm
Collimation of the Relativistic Jet in the Quasar 3C 273

Abstract
The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline interferometry (VLBI) observations of the archetypical quasar 3C 273 at 86 GHz, performed with the Global Millimeter VLBI Array, for the first time including the Atacama Large Millimeter/submillimeter Array. Our observations achieve a high angular resolution down to ∼60 μas, resolving the innermost part of the jet ever on scales of ∼105 Schwarzschild radii. Our observations, including close-in-time High Sensitivity Array observations of 3C 273 at 15, 22, and 43 GHz, suggest that the inner jet collimates parabolically, while the outer jet expands conically, similar to jets from other nearby low-luminosity AGNs. We discovered the jet collimation break around 107 Schwarzschild radii, providing the first compelling evidence for structural transition in a quasar jet. The location of the collimation break for 3C 273 is farther downstream from the sphere of gravitational influence (SGI) from the central SMBH. With the results for other AGN jets, our results show that the end of the collimation zone in AGN jets is governed not only by the SGI of the SMBH but also by the more diverse properties of the central nuclei.

https://iopscience.iop.org/article/10.3847/1538-4357/ac97e5
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/23/2022 11:07 am
It’s not something I imagine that the general public are aware of balloon astronomy probably even amongst those interested in astronomy.

Quote
NASA’s Balloon Program Analysis Group recently presented a roadmap to NASA, to guide them on how to plan and fund future balloon astronomy programs. Balloons have been used for over a century to conduct physics experiments, astronomical observations and Earth observing work, but remain relatively unknown to the general public. Balloon astronomy share many advantages with space telescopes, but at a fraction of the cost.

https://www.universetoday.com/158531/many-next-generation-telescopes-are-carried-on-balloons-heres-what-the-next-decade-holds-in-balloon-astronomy/

Related report:

A Roadmap For Scientific Ballooning 2020-2030

From 2018 to 2020, the Scientific Balloon Roadmap Program Analysis Group (Balloon Roadmap PAG) served as an community-based, interdisciplinary forum for soliciting and coordinating community analysis and input in support of the NASA Scientific Balloon Program. The Balloon Roadmap PAG was tasked with articulating and prioritizing the key science drivers and needed capabilities of the Balloon Program for the next decade. Additionally, the Balloon Roadmap PAG was asked to evaluate the potential for achieving science goals and maturing technologies of the Science Mission Directorate, evaluate the Balloon Program goals towards community outreach, and asses commercial balloon launch opportunities. The culmination of this work has been a written report submitted to the NASA Astrophysics Division Director.

https://arxiv.org/abs/2210.01198
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/26/2022 03:30 pm
SN 2022ann: A type Icn supernova from a dwarf galaxy that reveals helium in its circumstellar environment

We present optical and near-infrared (NIR) observations of the Type Icn supernova (SN Icn) 2022ann, the fifth member of its newly identified class of SNe. Its early optical spectra are dominated by narrow carbon and oxygen P-Cygni features with absorption velocities of 800 km/s; slower than other SNe Icn and indicative of interaction with a dense, H/He-poor circumstellar medium (CSM) that is outflowing slower than a typical Wolf-Rayet wind velocity of &gt;1000 km/s. We identify helium in NIR spectra obtained two weeks after maximum and in optical spectra at three weeks, demonstrating that the CSM is not fully devoid of helium. We never detect broad spectral features from SN ejecta, including in spectra extending to the nebular phase, a unique characteristic among SNe~Icn. Compared to other SNe Icn, SN 2022ann has a low luminosity, with a peak o-band absolute magnitude of -17.7, and evolves slowly. We model the bolometric light curve and find it is well-described by 1.7 M_Sun of SN ejecta interacting with 0.2 M_sun of CSM. We place an upper limit of 0.04 M_Sun of Ni56 synthesized in the explosion. The host galaxy is a dwarf galaxy with a stellar mass of 10^7.34 M_Sun (implied metallicity of log(Z/Z_Sun) ≈ 0.10) and integrated star-formation rate of log(SFR) = -2.20 M_sun/yr; both lower than 97\% of the galaxies observed to produce core-collapse supernovae, although consistent with star-forming galaxies on the galaxy Main Sequence. The low CSM velocity, nickel and ejecta masses, and likely low-metallicity environment disfavour a single Wolf-Rayet progenitor star. Instead, a binary companion star is likely required to adequately strip the progenitor before explosion and produce a low-velocity outflow. The low CSM velocity may be indicative of the outer Lagrangian points in the stellar binary progenitor, rather than from the escape velocity of a single Wolf-Rayet-like massive star.

https://arxiv.org/abs/2211.05134
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/28/2022 04:11 pm
An investigation of open clusters Berkeley 68 and Stock 20 using CCD UBV and Gaia DR3 data

We performed detailed photometric and astrometric analyses of the open star clusters Berkeley 68 and Stock 20. This was based on ground-based CCD UBV photometric data complemented by space-based Gaia Data Release 3 photometry and astrometry. 198 stars were identified as likely cluster members for Berkeley 68 and 51 for Stock 20. Two-color diagrams were used to derive the reddening and photometric metallicity for each cluster. The reddening for Berkeley 68 is E(B−V)=0.520±0.032 and 0.400±0.048 mag for Stock 20. Photometric metallicity [Fe/H] is −0.13±0.08 dex for Berkeley 68, and −0.01±0.06 dex for Stock 20. Keeping as constant reddening and metallicity, we determined the distance moduli and ages of the clusters through fitting isochrones to the UBV and Gaia based color-magnitude diagrams. Photometric distances are d=3003±165 pc for Berkeley 69 and 2911±216 pc for Stock 20. The cluster ages are 2.4±0.2 Gyr and 50±10 Myr for Berkeley 68 and Stock 20, respectively. Present-day mass function slopes were found to be Γ=1.38±0.71 and Γ=1.53±0.39 for Berkeley 68 and Stock 20, respectively. These values are compatible with the value of Salpeter (1955). The relaxation times were estimated as 32.55 Myr and 23.17 Myr for Berkeley 68 and Stock 20, respectively. These times are less than the estimated cluster ages, indicating that both clusters are dynamically relaxed. Orbit integration was carried out only for Berkeley 68 since radial velocity data was not available for Stock 20. Analysis indicated that Berkeley 68 was born outside the solar circle and belongs to the thin-disc component of the Milky Way.

https://arxiv.org/abs/2211.09825
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2022 02:52 pm
GD 99: Re-investigation of an old ZZ Ceti companion

Context. Thanks to photometric space missions, we have access to more and more information on the properties of white dwarf stars, especially pulsating ones. In the case of pulsators, we have the opportunity to get an insight into their otherwise hidden interiors by the means of asteroseismology. In addition to space-based observations, we also take advantage of the opportunity to study the pulsations of white dwarf stars from the ground, either as observations that are complementary to space-based measurements or individual observing runs on selected targets across long timescales.
Aims. We aim to investigate long-term, single-site observations of the bright, yet scarcely studied ZZ Ceti star, GD 99. Our main goals are to determine as many eigenmodes for asteroseismology as possible and then to carry out a seismic analysis of this target.
Methods. We performed a Fourier analysis of the light curves obtained in different epochs. After finding the normal modes of the pulsation, we ran the 2018 version of the White Dwarf Evolution Code to build model grids for the period fits. We compared the seismic distance of the best-fit model with the geometric value provided by Gaia measurements.
Results. We find that GD 99 is rich in pulsation modes in the 200-1100 s period range, as we detected seven new periods. Together with the literature data, we were able to use 11 modes for the asteroseismic fits. We accepted an asteroseismic model solution with Teff = 13 500 K and M* = 0.80 Msun as a best fit, however, this suggests a hotter and more massive star than we might have expected based on the spectroscopic values. We also estimated the rotational rate of the star to be 13.17 h, based on TESS observations.

https://arxiv.org/abs/2211.11676
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2022 03:47 pm
Data Sonification: Pismis 24:

https://youtu.be/KAIm5UE3Rvg
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/30/2022 05:58 am
Quote
A team of researchers has discovered at least two new minerals that have never before been seen on Earth in a 15 ton meteorite found two years ago in Somalia—the ninth largest meteorite ever found.

https://www.forbes.com/sites/davidbressan/2022/11/29/scientists-discover-two-alien-minerals-in-meteorite/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/02/2022 02:44 pm
Big fireball streaks across skies over at least 12 US states, Canada:

https://youtu.be/zO7uw--PAhc
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/02/2022 04:04 pm
Investigating the origin of optical and X-ray pulsations of the transitional millisecond pulsar PSR J1023+0038

PSR J1023+0038 is the first millisecond pulsar that was ever observed as an optical and UV pulsar. So far, it is the only optical transitional millisecond pulsar. The rotation- and accretion-powered emission mechanisms hardly individually explain the observed characteristics of optical pulsations. A synergistic model, combining these standard emission processes, was proposed to explain the origin of the X-ray/UV/optical pulsations. We study the phase lag between the pulses in the optical and X-ray bands to gain insight into the physical mechanisms that cause it. We performed a detailed timing analysis of simultaneous or quasi-simultaneous observations in the X-ray band, acquired with the XMM-Newton and NICER satellites, and in the optical band, with the fast photometers SiFAP2 (mounted at the 3.6 m Telescopio Nazionale Galileo) and Aqueye+ (mounted at the 1.8 m Copernicus Telescope). We estimated the time lag of the optical pulsation with respect to that in the X-rays by modeling the folded pulse profiles with two harmonic components. Optical pulses lag the X-ray pulses by ∼ 150 μs in observations acquired with instruments (NICER and Aqueye+) whose absolute timing uncertainty is much smaller than the measured lag. We also show that the phase lag between optical and X-ray pulsations lies in a limited range of values, δϕ∈ (0 − 0.15), which is maintained over timescales of about five years. This indicates that both pulsations originate from the same region, and it supports the hypothesis of a common emission mechanism. Our results are interpreted in the shock-driven mini pulsar nebula scenario. This scenario suggests that optical and X-ray pulses are produced by synchrotron emission from the shock that formed within a few light cylinder radii away (∼ 100 km) from the pulsar, where its striped wind encounters the accretion disk inflow.

https://arxiv.org/abs/2211.12975
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/05/2022 04:31 pm
Long-term multi-wavelength study of 1ES 0647+250

The BL Lac object 1ES 0647+250 is one of the few distant γ-ray emitting blazars detected at very high energies (VHE, ≳100 GeV) during a non-flaring state. It was detected with the MAGIC telescopes during its low activity in the years 2009-2011, as well as during three flaring activities in the years 2014, 2019 and 2020, with the highest VHE flux in the latter epoch. An extensive multi-instrument data set was collected within several coordinated observing campaigns throughout these years. We aim to characterise the long-term multi-band flux variability of 1ES 0647+250, as well as its broadband spectral energy distribution (SED) during four distinct activity states selected in four different epochs, in order to constrain the physical parameters of the blazar emission region under certain assumptions. We evaluate the variability and correlation of the emission in the different energy bands with the fractional variability and the Z-transformed Discrete Correlation Function, as well as its spectral evolution in X-rays and γ rays. Owing to the controversy in the redshift measurements of 1ES 0647+250 reported in the literature, we also estimate its distance in an indirect manner through the comparison of the GeV and TeV spectra from simultaneous observations with Fermi-LAT and MAGIC during the strongest flaring activity detected to date. Moreover, we interpret the SEDs from the four distinct activity states within the framework of one-component and two-component leptonic models, proposing specific scenarios that are able to reproduce the available multi-instrument data.

https://arxiv.org/abs/2211.13268
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/06/2022 04:10 pm
Decade Long Timing Study of the Black Widow Millisecond Pulsar J1544+4937

Results from 11 years of radio timing for eclipsing black widow millisecond pulsar (MSP) binary, J1544+4937, is presented in this paper. We report a phase-connected timing model for this MSP, using observations with the Giant Metrewave Radio Telescope (GMRT) at multiple frequencies and with Green Bank Telescope (GBT). This is the longest-duration timing study of any galactic field MSP with the GMRT. While extending the timing baseline from the existing 1.5 years to about a decade we report the first detection for a significant value of proper motion (μT∼ 10.14(5) mas/year) for this pulsar. Temporal variations of dispersion measure (ΔDM ∼10−3 pc cm−3) manifested by significant determination of 1st, 2nd, and 3rd order DM derivatives are observed along the line of sight to the pulsar. We also noticed frequency-dependent DM variations of the order of 10−3 pc cm−3, which could arise due to spatial electron density variations in the interstellar medium. This study has revealed a secular variation of the orbital period for this MSP for the first time. We investigated possible causes and propose that variation in the gravitational quadrupole moment of the companion could be responsible for the observed temporal changes in the orbital period.

https://arxiv.org/abs/2211.14107
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/06/2022 04:23 pm
New Measurement Resolves Key Astrophysical Fe XVII Oscillator Strength Problem

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.245001

Quote
”This strengthens the confidence in the quantum mechanical calculations used to analyze astrophysical spectra. This applies particularly to lines for which there are no experimental reference values," Kühn emphasizes the significance of the new result. Moreover, the spectra of the space telescopes can now be evaluated with greater accuracy.

This also applies to two large X-ray observatories that are soon to be launched into space: The Japanese-led X-Ray Imaging Spectroscopy Mission (XRISM, launch in May 2023) and the Athena X-Ray Observatory of the European Space Agency ESA (launch in the early 2030s).

https://phys.org/news/2022-12-x-ray-analysis-four-decade-enigma-cosmic.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/06/2022 04:33 pm
Quote
After 30 years of planning and negotiations, construction begins this week on the Square Kilometre Array (SKA), the world’s largest radio-astronomy observatory. The giant instrument—to be built across sprawling sites in Australia and Africa—will collect the radio signals emitted by celestial objects and will hopefully shed light on some of the most enigmatic problems in astronomy, such as the nature of dark matter and how galaxies form.
On Monday, astronomers and local communities will travel to the remote sites in South Africa’s Northern Cape and Western Australia to celebrate the milestone with officials from the SKA Observatory (SKAO), the intergovernmental organization in charge of the telescopes.

https://www.scientificamerican.com/article/construction-of-worlds-largest-radio-observatory-is-finally-under-way1/
Title: Re: Astronomy & Planetary Science Thread
Post by: jbenton on 12/07/2022 03:53 pm
It turns out that HIPASS J1131-31, aka the "Peekaboo Galaxy", is an extremely metal poor (XMP) galaxy. This makes it the youngest - and nearest - XMP galaxy known. We generally expect metal poor stars and galaxies to be old. Interestingly enough, it's also now one of the most extremely metal poor XMP galaxies known:

https://www.nasa.gov/feature/goddard/2022/peekaboo-tiny-hidden-galaxy-provides-a-peek-into-the-past (https://www.nasa.gov/feature/goddard/2022/peekaboo-tiny-hidden-galaxy-provides-a-peek-into-the-past)

Quote
... Only 1,200 light-years across, the tiny galaxy HIPASS J1131–31 has been nicknamed "Peekaboo" because of its emergence in the past 50-100 years from behind the fast-moving star that was obscuring astronomers' ability to detect it.

...

Peekaboo was first detected as a region of cold hydrogen more than 20 years ago with the Australian Parkes radio telescope Murriyang, in the HI Parkes All Sky Survey by professor Bärbel Koribalski, who is an astronomer at Australia's national science agency CSIRO and a co-author of the latest research study on Peekaboo's metallicity. Far-ultraviolet observations by NASA's space-based Galaxy Evolution Explorer mission showed it to be a compact blue dwarf galaxy.

"At first we did not realize how special this little galaxy is," Koribalski said of Peekaboo. "Now with combined data from the Hubble Space Telescope, the Southern African Large Telescope (SALT), and others, we know that the Peekaboo Galaxy is one of the most metal-poor galaxies ever detected."

NASA's Hubble Space Telescope was able to resolve about 60 stars in the tiny galaxy, almost all of which appear to be a few billion years old or younger. Measurements of Peekaboo's metallicity by SALT completed the picture. Together, these findings underline the major difference between Peekaboo and other galaxies in the local universe, which typically have ancient stars that are many billions of years old. Peekaboo's stars indicate that it is one of the youngest and least-chemically-enriched galaxies ever detected in the local universe. This is very unusual, as the local universe has had about 13 billion years of cosmic history to develop.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/07/2022 04:39 pm
A nearby long gamma-ray burst from a merger of compact objects

Abstract
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive stars1, and those of short (less than two seconds) duration by the merger of compact objects, such as two neutron stars2. A third class of events with hybrid high-energy properties was identified3, but never conclusively linked to a stellar progenitor. The lack of bright supernovae rules out typical core-collapse explosions4,5,6, but their distance scales prevent sensitive searches for direct signatures of a progenitor system. Only tentative evidence for a kilonova has been presented7,8. Here we report observations of the exceptionally bright GRB 211211A, which classify it as a hybrid event and constrain its distance scale to only 346 megaparsecs. Our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (approximately 1042 erg per second) kilonova possibly formed in the ejecta of a compact object merger.

https://www.nature.com/articles/s41586-022-05327-3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/07/2022 04:46 pm
Deep X-ray and radio observations of the first outburst of the young magnetar Swift J1818.0-1607

Swift J1818.0-1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B~3E14 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its first outburst in March 2020 until October 2021, as well as INTEGRAL upper limits on its hard X-ray emission. The 1-10 keV magnetar spectrum is well modeled by an absorbed blackbody with a temperature of kT_BB~1.1 keV, and apparent reduction in the radius of the emitting region from ~0.6 to ~0.2 km. We also confirm the bright diffuse X-ray emission around the source extending between ~50'' and ~110''. A timing analysis revealed large torque variability, with an average spin-down rate nudot~-2.3E-11 Hz^2 that appears to decrease in magnitude over time. We also observed Swift J1818.0-1607 with the Karl G. Jansky Very Large Array (VLA) on 2021 March 22. We detected the radio counterpart to Swift J1818.0-1607 measuring a flux density of S_v = 4.38+/-0.05 mJy at 3 GHz, and a half ring-like structure of bright diffuse radio emission located at ~90'' to the west of the magnetar. We tentatively suggest that the diffuse X-ray emission is due to a dust scattering halo and that the radio structure may be associated with the supernova remnant of this young pulsar, based on its morphology.

https://arxiv.org/abs/2211.12391
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/07/2022 05:03 pm
The Strange Mystery of the Asteroid That Wasn’t:
https://youtu.be/bzsWo5adxKo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/08/2022 06:18 pm
The Rapidly Spinning Intermediate-Mass Black Hole 3XMM J150052.0+015452

A star tidally disrupted by a black hole can form an accretion disc with a super-Eddington mass accretion rate; the X-ray emission produced by the inner disc provides constraints on the black hole mass M and dimensionless spin parameter a. Previous studies have suggested that the M responsible for the tidal disruption event 3XMM J150052.0+015452 (hereafter J150052) is ∼105M, in the intermediate black hole (IMBH) regime. Fitting multi-epoch XMM-Newton and Chandra X-ray spectra obtained after 2008 during the source's decade-long decay, with our latest slim accretion disc model gives M=2.0+1.0−0.3×105M (at 68% confidence) and a&gt;0.97 (a 84.1% confidence lower limit). The spectra obtained between 2008-2014 are significantly harder than those after 2014, an evolution that can be well explained by including the effects of inverse-Comptonisation by a corona on the early-time spectra. The corona is present when the source accretion rate is super-Eddington, while there is no evidence for its effect in data obtained after 2014, when the mass accretion rate is around the Eddington-limit. Based on our spectral study, we infer that the corona is optically thick and warm (kTe=2.3+2.7−0.8 keV). Our mass and spin measurements of J150052 confirm it as an IMBH and point to a rapid, near extremal, spin. These M and a values rule out both vector bosons and axions of masses ∼10−16 eV.

https://arxiv.org/abs/2211.16936
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/11/2022 08:13 pm
Quote
A new analysis of Hubble data has clinched it: There's too much light in the space around the Solar System.

Not much extra light, to be sure. Just a subtle, ghostly glow, a faint excess that can't be accounted for in a census of all the light-emitting objects.

Quote
The strongest possibility? A dust component to the Solar System that we haven't yet directly detected: tiny particles of dust and ice from a population of comets traveling inwards from the dark reaches of the Solar System, reflecting sunlight and generating a diffuse, global glow.

This source would be a bit closer to us than the extra light detected by the New Horizons space probe, which found an optical light excess in the space beyond Pluto, outside the Solar System.

https://www.sciencealert.com/a-ghostly-glow-of-light-surrounds-the-solar-system-and-nobody-can-explain-it/amp
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/12/2022 04:41 pm
Broadband mHz QPOs and spectral study of LMC X−4 with AstroSat

We report the results of broadband timing and spectral analysis of data from an AstroSat observation of the High Mass X-ray binary LMC X−4. The Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) instruments on-board the AstroSat observed the source in August 2016. A complete X-ray eclipse was detected with the LAXPC. The 3−40 keV power density spectrum showed the presence of coherent pulsations along with a ∼26 mHz quasi-periodic oscillation feature. The spectral properties of LMC X−4 were derived from a joint analysis of the SXT and LAXPC spectral data. The 0.5−25 keV persistent spectrum comprised of an absorbed high energy cutoff power law with photon index of Γ∼ 0.8 and cutoff at ∼16 keV, a soft thermal component with kTBB∼ 0.14 keV and Gaussian components corresponding to Fe Kα, Ne \textsc{ix} and Ne \textsc{x} emission lines. Assuming a source distance of 50 kpc, we determined 0.5--25 keV luminosity to be ∼2×1038 erg s−1.

https://arxiv.org/abs/2212.01003
Title: Re: Astronomy & Planetary Science Thread
Post by: jbenton on 12/13/2022 03:47 pm
This is a couple weeks old, but I found it today:

New constraints on possible phosphine concentrations in the Venusian atmosphere, from analyzing some SOFIA data:
https://eos.org/research-spotlights/if-there-is-phosphine-on-venus-there-isnt-much (https://eos.org/research-spotlights/if-there-is-phosphine-on-venus-there-isnt-much)

Quote
Data collected ... during three observing flights revealed no clear evidence of phosphine, the researchers report. If any phosphine is present in Venus’s atmosphere, and assuming the abundance is constant in time, the new observations indicate an upper limit on its concentration of 0.8 part per billion. This level is the most stringent upper limit presented to date for the entire Earth-facing hemisphere of Venus.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/14/2022 03:32 pm
The chemical compositions of multiple stellar populations in the globular cluster NGC 2808

Pseudo two-colour diagrams or Chromosome maps (ChM) indicate that NGC 2808 host five different stellar populations. The existing ChMs have been derived by the Hubble Space Telescope photometry, and comprise of stars in a small field of view around the cluster centre. To overcome these limitations, we built a ChM with U,B,I photometry from ground-based facilities that disentangle the multiple stellar populations of NGC 2808 over a wider field of view. We used spectra collected by GIRAFFE@VLT in a sample of 70 red giant branch (RGB) and seven asymptotic giant branch (AGB) stars to infer the abundances of C, N, O, Al, Fe, and Ni, which combined with literature data for other elements (Li, Na, Mg, Si, Ca, Sc, Ti, Cr and Mn), and together with both the classical and the new ground-based ChMs, provide the most complete chemical characterisation of the stellar populations in NGC 2808 available to date. As typical of the multiple population phenomenon in globular clusters, the light elements vary from one stellar population to another; whereas the iron peak elements show negligible variation between the different populations (at a level of ≲0.10~dex). Our AGB stars are also characterised by the chemical variations associated with the presence of multiple populations, confirming that this phase of stellar evolution is affected by the phenomenon as well. Intriguingly, we detected one extreme O-poor AGB star (consistent with a high He abundance), challenging stellar evolution models which suggest that highly He-enriched stars should avoid the AGB phase and evolve as AGB-manqué star.

https://arxiv.org/abs/2212.01319
Title: Astronomy & Planetary Science Thread
Post by: Star One on 12/15/2022 04:25 pm
Astronomers find that two exoplanets may be mostly water

https://phys.org/news/2022-12-montreal-astronomers-exoplanets.html

Related video:

https://youtu.be/jjywIBBcP3I
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/19/2022 01:50 pm
The Possible Tidal Demise of Kepler's First Planetary System

Abstract
We present evidence of tidally-driven inspiral in the Kepler-1658 (KOI-4) system, which consists of a giant planet (1.1RJ, 5.9MJ) orbiting an evolved host star (2.9R, 1.5M). Using transit timing measurements from Kepler, Palomar/WIRC, and TESS, we show that the orbital period of Kepler-1658b appears to be decreasing at a rate $\dot{P}={131}_{-22}^{+20}$ ms yr−1, corresponding to an infall timescale $P/\dot{P}\approx 2.5\,\mathrm{Myr}$. We consider other explanations for the data including line-of-sight acceleration and orbital precession, but find them to be implausible. The observed period derivative implies a tidal quality factor ${Q}_{\star }^{{\prime} }={2.50}_{-0.62}^{+0.85}\times {10}^{4}$, in good agreement with theoretical predictions for inertial wave dissipation in subgiant stars. Additionally, while it probably cannot explain the entire inspiral rate, a small amount of planetary dissipation could naturally explain the deep optical eclipse observed for the planet via enhanced thermal emission. As the first evolved system with detected inspiral, Kepler-1658 is a new benchmark for understanding tidal physics at the end of the planetary life cycle.

https://iopscience.iop.org/article/10.3847/2041-8213/aca47e
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/19/2022 02:00 pm
Simultaneous radio and optical polarimetry of GRB 191221B afterglow

Abstract
Gamma-ray bursts (GRBs) are the most luminous transients in the universe and are utilized as probes of early stars, gravitational wave counterparts and collisionless shock physics. In spite of studies on polarimetry of GRBs in individual wavelengths that characterized intriguing properties of prompt emission and afterglow, no coordinated multi-wavelength measurements have yet been performed. Here we report the first coordinated simultaneous polarimetry in the optical and radio bands for the afterglow associated with the typical long GRB 191221B. Our observations successfully caught the radio emission, which is not affected by synchrotron self-absorption, and show that the emission is depolarized in the radio band compared with the optical one. Our simultaneous polarization angle measurement and temporal polarization monitoring indicate the existence of cool electrons that increase the estimate of jet kinetic energy by a factor of more than 4 for this GRB afterglow. Further coordinated multi-wavelength polarimetric campaigns would improve our understanding of the total jet energies and magnetic field configurations in the emission regions of various types of GRBs, which are required to comprehend the mass scales of their progenitor systems and the physics of collisionless shocks.

https://www.nature.com/articles/s41550-022-01832-7
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/20/2022 01:33 pm
Exploring the single-pulse behaviours of PSR J0628+0909 with FAST

ABSTRACT
More than 100 rotating radio transients (RRATs) have been discovered since 2006. However, it is unclear whether RRATs radiate in nulling states. PSR J0628+0909 has been classified as an RRAT. In this paper, we study the single pulses and integrated pulse profile of PSR J0628+0909 to check whether we can detect pulsed radio emission in the nulling states. We also aim to study the polarization of the RRAT and its relationship to the general pulsar population. We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to observe PSR J0628+0909 in the frequency range from 1.0 to 1.5 GHz. We searched for strong single pulses and looked for pulsed emission in the RRAT nulling states. Polarization profiles, the single-pulse energy distribution, and waiting-time statistics were measured. The Faraday rotation measure and dispersion measure values are updated with the current observation. The single-pulse polarization behaviours show great diversity, similar to the case of pulsars. Based on the integrated pulse profile and single-pulse energy statistics, we argue that continuous pulsar-like emission exists in addition to the transient-like burst emission for PSR J0628+0909. We find that the pulse waiting time is not correlated with the pulse energy and conclude that the strong transient emission of RRAT is not generated by the energy store–release mechanism.

https://academic.oup.com/mnras/article-abstract/518/1/1418/6840068?redirectedFrom=fulltext
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/21/2022 01:15 pm
J1407b: Super-Saturn

https://exoplanets.nasa.gov/resources/242/j1407b-super-saturn/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/21/2022 04:09 pm
Two temperate Earth-mass planets orbiting the nearby star GJ 1002

https://www.aanda.org/component/article?access=doi&amp;doi=10.1051/0004-6361/202244991

The star system is comparatively close to us in cosmological terms at just under sixteen light years distant, and features two planets with masses similar to the Earth’s orbiting in the star’s habitable zone. There may also be a third larger planet further out in orbit about the host star.

https://phys.org/news/2022-12-earth-mass-exoplanets-orbiting-nearby-star.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/27/2022 04:44 pm
Timing analysis of the 2022 outburst of the accreting millisecond X-ray pulsar SAX J1808.4−3658: hints of an orbital shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4−3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of ≃1×1036ergs−1 in about a week, the pulsar entered in a ∼1 month-long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of ν˙SD=−(1.15±0.06)×10−15Hzs−1, compatible with the spin-down torque of a ≈1026Gcm3 rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behaviour of the orbit is dominated by a ∼11s modulation of the orbital phase epoch consistent with a ∼21yr period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star.

https://arxiv.org/abs/2212.09778
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/28/2022 03:45 pm
Investigating stellar variability in the open cluster region NGC 381

We study variable stars in the field of the open cluster NGC 381 using photometric data observed over 27 nights and identify a total of 57 variable stars out of which five are member stars. The variable stars are classified based on their periods, amplitudes, light curve shapes, and locations in the H-R diagram. We found a rich variety of variable stars in the cluster. We identified a total of 10 eclipsing binaries out of which 2 are Algol type (EA) while 8 are W UMa type (EW) binaries. The estimated ages of these EW binaries are greater than 0.6 Gyr which is in agreement with the formation time constraint of > 0.6 Gyr on short-period eclipsing binaries. The estimation of the physical parameters of the three EW type binaries is done using PHOEBE model-fitting software. The pulsating variable stars include one each from {\delta} Scuti and {\gamma} Dor variability class. We determined the pulsation modes of pulsating variables with the help of the FAMIAS package. We obtained 15 rotational variables stars comprising four dwarf stars identified on the basis log(g) versus log(Tef f ) diagram. These dwarf stars are found to have generally larger periods than the remaining rotational variables.

https://arxiv.org/abs/2212.09386
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/03/2023 04:06 pm
Vela pulsar wind nebula X-rays are polarized to near the synchrotron limit

Abstract
Pulsar wind nebulae are formed when outflows of relativistic electrons and positrons hit the surrounding supernova remnant or interstellar medium at a shock front. The Vela pulsar wind nebula is powered by a young pulsar (B0833-45, aged 11,000 years)1 and located inside an extended structure called Vela X, which is itself inside the supernova remnant2. Previous X-ray observations revealed two prominent arcs that are bisected by a jet and counter jet3,4. Radio maps have shown high linear polarization of 60% in the outer regions of the nebula5. Here we report an X-ray observation of the inner part of the nebula, where polarization can exceed 60% at the leading edge—approaching the theoretical limit of what can be produced by synchrotron emission. We infer that, in contrast with the case of the supernova remnant, the electrons in the pulsar wind nebula are accelerated with little or no turbulence in a highly uniform magnetic field.

https://www.nature.com/articles/s41586-022-05476-5
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/04/2023 01:54 pm
Variability and Spectral Behavior of Gamma-ray Flares of 3C 279

3C 279 showed enhanced flux variations in Fermi-LAT {\gamma}-ray observations from January to June 2018. We present a detailed Fermi-LAT analysis to investigate the variability and spectral behaviors of 3C 279 during the {\gamma}-ray flares in 2018. In this work, we analyzed the {\gamma}-ray spectra and found that the spectra in either the flaring or quiescent states do not show any clear breaks (or cutoffs). This indicates that the dissipation region is outside the broad-line region, and the energy dissipation may be due to the inverse Compton process of scattering the dust torus infrared photons, this result is also consistent with that in Tolamatti et al. An external inverse Compton scattering of dusty torus (DT) photons is employed to calculate the broadband spectral energy distribution (SED). This model was further supported by the fact that we found flare decay timescale was consistent with the cooling time of relativistic electrons through DT photons. During the SED modeling, a relatively harder spectrum for the electron energy distribution (EED) is found and suggests these electrons may not be accelerated by the shock that happened in the dissipation region. Besides, the magnetic reconnection is also ruled out due to a low magnetization ratio. Thus, we suggest an injection of higher-energy electrons from outside the blob and raising the flare.

https://arxiv.org/abs/2212.13395
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/04/2023 04:11 pm
Study investigates the evolution of X-ray binary system GX 301-2

https://phys.org/news/2023-01-evolution-x-ray-binary-gx-.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/05/2023 01:08 pm
Newly discovered comet could be visible to the naked eye in Jan. 2023:

https://youtu.be/iaDlbYQ4GrU
Title: Re: Astronomy & Planetary Science Thread
Post by: su27k on 01/13/2023 02:43 am
https://twitter.com/jeff_foust/status/1613642385715793921

Quote
Quite the list of calamities NSF-funded astronomy facilities have dealt with, mentioned at an #AAS241 town hall:

- Arecibo collapse
- Kitt Peak fire
- ALMA cyberattack
- Chipped primary mirror at Gemini North
- Fractured wheel at Green Bank Telescope
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/16/2023 04:10 pm
Discovery of a resolved white dwarf-brown dwarf binary with a small projected separation: SDSS J222551.65+001637.7AB

We present the confirmation of SDSS J222551.65+001637.7AB as a closely separated, resolved, white dwarf-brown dwarf binary. We have obtained spectroscopy from GNIRS and seeing-limited Ks-band imaging from NIRI on Gemini North. The target is spatially resolved into its constituent components: a 10926± 246 K white dwarf, with log g=8.214±0.168 and a mass of 0.66+0.11−0.06 M⊙, and an L4 brown dwarf companion, which are separated by 0.9498±0.0022". We derive the fundamental properties of the companion from the Sonora-Bobcat evolutionary models, finding a mass of 25−53 MJup and a radius of 0.101−0.128 R⊙ for the brown dwarf, at a confidence level of 1σ. We use wdwarfdate to determine the age of the binary as 1.97+4.41−0.76 Gyr. A kinematic analysis shows that this binary is likely a member of the thick disc. The distance to the binary is 218+14−13 pc, and hence the projected separation of the binary is 207+13−12 AU. Whilst the white dwarf progenitor was on the main sequence the binary separation would have been 69±5 AU. SDSS J222551.65+001637.7AB is the third closest spatially resolved white dwarf-brown dwarf binary after GD 165AB and PHL 5038AB.

https://arxiv.org/abs/2301.02101
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/18/2023 01:56 pm
MeerKAT discovery of 13 new pulsars in Omega Centauri

The most massive globular cluster in our Galaxy, Omega Centauri, is an interesting target for pulsar searches, because of its multiple stellar populations and the intriguing possibility that it was once the nucleus of a galaxy that was absorbed into the Milky Way. The recent discoveries of pulsars in this globular cluster and their association with known X-ray sources was a hint that, given the large number of known X-ray sources, there is a much larger undiscovered pulsar population. We used the superior sensitivity of the MeerKAT radio telescope to search for pulsars in Omega Centauri. In this paper, we present some of the first results of this survey, including the discovery of 13 new pulsars; the total number of known pulsars in this cluster currently stands at 18. At least half of them are in binary systems and preliminary orbital constraints suggest that most of the binaries have light companions. We also discuss the ratio between isolated and binaries pulsars and how they were formed in this cluster.

https://arxiv.org/abs/2301.03864
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/19/2023 03:53 pm
Comprehensive spectroscopic and photometric study of pulsating eclipsing binary star AI Hya

The pulsating eclipsing binaries are remarkable systems that provide an opportunity to probe the stellar interior and to determine the fundamental stellar parameters precisely. Especially the detached eclipsing binary systems with (a) pulsating component(s) are significant objects to understand the nature of the oscillations since the binary effects in these systems are negligible. Recent studies based on space data have shown that the pulsation mechanisms of some oscillating stars are not completely understood. Hence, comprehensive studies of a number of pulsating stars within detached eclipsing binaries are important. In this study, we present a detailed analysis of the pulsating detached eclipsing binary system AI Hya which was studied by two independent groups with different methods. We carried out a spectroscopic survey to estimate the orbital parameters via radial velocity measurements and the atmospheric parameters of each binary component using the composite and/or disentangled spectra. We found that the more luminous component of the system is a massive, cool and chemically normal star while the hotter binary component is a slightly metal-rich object. The fundamental parameters of AI Hya were determined by the analysis of binary variations and subsequently used in the evolutionary modelling. Consequently, we obtained the age of the system as 850 ± 20 Myr and found that both binary components are situated in the Delta Scuti instability strip. The frequency analysis revealed pulsation frequencies between the 5.5 - 13.0 d−1 and we tried to estimate which binary component is the pulsating one. However, it turned out that those frequencies could originate from both binary components.

https://arxiv.org/abs/2301.04409
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/24/2023 04:43 pm
Kinematics and Origin of Gas in the Disk Galaxy NGC 2655

The new observational data concerning distribution, excitation, and kinematics of the ionized gas in the giant early-type disk galaxy NGC 2655 obtained at the 6m telescope of the Special Astrophysical Observatory (SAO RAS) and at the 2.5m telescope of the Caucasian Mountain Observatory of the Sternberg Astronomical Institute (CMO SAI MSU) are presented in this work. The joint analysis of these and earlier spectral observations has allowed us to make a conclusion about multiple nature of the gas in NGC 2655. Together with a proper large gaseous disk experiencing regular circular rotation in the equatorial plane of the stellar potential of the galaxy for billions years, we observe also remnants of a merged small satellite having striked the central part of NGC 2655 almost vertically for some 10 million years ago.

https://arxiv.org/abs/2301.05326
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2023 04:43 pm
SDSS J134441.83+204408.3: A highly asynchronous, short-period magnetic cataclysmic variable with a 56 MG field strength

When the accreting white dwarf in a magnetic cataclysmic variable star (mCV) has a field strength in excess of 10 MG, it is expected to synchronize its rotational frequency to the binary orbit frequency, particularly at small binary separations, due to the steep radial dependence of the magnetic field. We report the discovery of an mCV (SDSS J134441.83+204408.3; hereafter, J1344) that defies this expectation by displaying asynchronous rotation (Pspin/Porb=0.893) in spite of a high surface field strength (B=56 MG) and a short orbital period (114 min). Previously misidentified as a synchronously rotating mCV, J1344 was observed by TESS during sector 50, and the resulting power spectrum shows distinct spin and orbital frequencies, along with various sidebands and harmonics. Although there are several other asynchronous mCVs at short orbital periods, the presence of cyclotron humps in J1344's SDSS spectrum makes it possible to directly measure the field strength in the cyclotron-emitting region; a previously study estimated 65 MG based on its identification of two cyclotron humps, but we revise this to 56±2 MG based on the detection of a third hump and on our modeling of the cyclotron spectrum. Short-period mCVs with field strengths above 10 MG are normally expected to be synchronous, so the highly asynchronous rotation in J1344 presents an interesting challenge for theoretical studies of spin-period evolution.

https://arxiv.org/abs/2301.05723
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/26/2023 06:25 pm
Asteroid 2023 BU: Space rock to pass closer than some satellites https://www.bbc.co.uk/news/science-environment-64411469
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/27/2023 06:14 pm
Asteroid 2023 BU seen shortly before super close approach to Earth:

https://youtu.be/F55Wtl_AEkY
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/06/2023 04:08 pm
Influence of a mass transfer stability criterion on double white dwarf populations

Abstract
Context. Mass transfer stability is a key issue in studies of binary evolution. Critical mass ratios for dynamically stable mass transfer have been analyzed on the basis of an adiabatic mass loss model, finding that the donor stars on the giant branches tend to be more stable than that based on the composite polytropic stellar model. Double white dwarfs (DWDs) are of great importance in many fields and their properties would be significantly affected under the new mass transfer stability criterion.
Aims. We seek to investigate the influence of mass transfer stability on the formation and properties of DWD populations and discuss the implications in supernova Type Ia (SN Ia) and gravitational wave (GW) sources.
Methods. We performed a series of binary population synthesis, adopting the critical mass ratios from the adiabatic mass loss model (i.e., Ge’s model) and that of the composite polytropic model, respectively. In each simulation, 5 × 106 binaries were included and evolved from zero-age main sequence to the end of their evolution and the DWDs were gradually obtained.
Results. For Ge’s model, most of the DWDs are produced from the stable non-conservative Roche lobe (RL) overflow, along with a common-envelope (CE) ejection channel (RL+CE channel), regardless of the CE ejection efficiency, αCE. Conversely, the results of the polytropic model strongly depend on the adopted value of αCE. We find DWDs produced from the RL+CE channel have comparable WD masses and the mass ratio distribution peaks at around 1. Based on the magnitude-limited sample of DWDs, the space densities for the detectable DWDs and those with extremely low-mass WD (ELM WD) companions in Ge’s model is: 1347 kpc−3 and 473 kpc−3, respectively, which is close to what has been shown in observations. On the other hand, the polytropic model overpredicts space density of DWDs by a factor of about 2−3. We also find that the results of DWD merger rate distribution per Galaxy in Ge’s model reproduce the observations better than that of the polytropic model, and the merger rate of DWDs with ELM WD companions in the Galaxy is about 1.8 × 10−3 yr−1 in Ge’s model. This result is comparable to the observation estimation of 2 × 10−3 yr−1. The findings from Ge’s model predict a Galactic SN Ia rate of ∼6 × 10−3 yr−1 from DWDs, supporting observations of (5.4 ± 1.2)×10−3 yr−1. For the fiducial model of αCE = 1, the number of detectable GW sources in the polytropic model is larger than that in Ge’s model by about 35%.
Conclusions. We confirm that mass transfer stability plays an important role in the formation and properties of DWD populations as well as in the progenitors of SNe Ia and detectable GW sources. The results of Ge’s model support the observational DWD merger rate distribution per Galaxy and the space density of DWDs in the Galaxy.

https://www.aanda.org/articles/aa/full_html/2023/01/aa43893-22/aa43893-22.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/12/2023 06:50 pm
An Earth-sized Planet around an M5 Dwarf Star at 22 pc

We report on the discovery of an Earth-sized transiting planet (Rp=1.015±0.051R⊕) in a P=4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc. The planet candidate was first identified by analyzing the light curve data by the K2 mission, and is here shown to exist in the most recent data from TESS. Combining the light curves with the data secured by our follow-up observations including high-resolution imaging and near infrared spectroscopy with IRD, we rule out false positive scenarios, finding a low false positive probability of 2×10−4. Based on IRD's radial velocities of K2-415, which were sparsely taken over three years, we obtain the planet mass of 3.0±2.7M⊕ (Mp<7.5M⊕ at 95% confidence) for K2-415b. Being one of the lowest mass stars (≈0.16M⊙) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.

https://arxiv.org/abs/2302.00699
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/13/2023 06:08 am
Asteroid lights up sky above English Channel https://www.bbc.co.uk/news/uk-64621721
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/13/2023 03:46 pm
DESI z >~ 5 Quasar Survey. I. A First Sample of 400 New Quasars at z ~ 4.7-6.6

We report the first results of a high-redshift (z >~ 5) quasar survey using the Dark Energy Spectroscopic Instrument (DESI). As a DESI secondary target program, this survey is designed to carry out a systematic search and investigation of quasars at z >~ 5, up to redshift 6.8. The target selection is based on the DESI Legacy Imaging Surveys (the Legacy Surveys) DR9 photometry, combined with the Pan-STARRS1 data and J-band photometry from public surveys. A first quasar sample has been constructed from the DESI Survey Validation 3 (SV3) and first-year observations until May 2022. This sample includes more than 400 new quasars at redshift 4.7 <= z < 6.6, down to 21.5 magnitude in the z band, discovered from 35% of the entire target sample. Remarkably, there are 220 new quasars identified at z >= 5, more than one third of existing quasars previously published at this redshift. The observations so far result in an average success rate of 23% at z > 4.7. The current spectral dataset has already allowed analysis of interesting individual objects (e.g., quasars with damped Lyα absorbers and broad absorption line features), and statistical analysis will follow the survey's completion. A set of science projects will be carried out leveraging this program, including quasar luminosity function, quasar clustering, intergalactic medium, quasar spectral properties, intervening absorbers, and properties of early supermassive black holes. Additionally, a sample of 38 new quasars at z ~ 3.8-5.7 discovered from a pilot survey in the DESI SV1 is also published in this paper.

https://arxiv.org/abs/2302.01777
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/16/2023 04:16 pm
Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus

Abstract
In this paper, we report the discovery of an isolated, peculiar compact cloud with a steep velocity gradient at 2.′6 northwest of Sgr A*. This “Tadpole” molecular cloud is unique owing to its characteristic head-tail structure in the position–velocity space. By tracing the CO J = 3–2 intensity peak in each velocity channel, we noticed that the kinematics of the Tadpole can be well reproduced by a Keplerian motion around a point-like object with a mass of 1 × 105 M. Changes in line intensity ratios along the orbit are consistent with the Keplerian orbit model. The spatial compactness of the Tadpole and absence of bright counterparts in other wavelengths indicate that the object could be an intermediate-mass black hole.

https://iopscience.iop.org/article/10.3847/1538-4357/aca66a
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/17/2023 07:26 pm
How to do astrophotography on the Samsung Galaxy S23 Ultra:

https://youtu.be/0h26B05QwNo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/18/2023 06:18 pm
NASA's planetary radar captures detailed view of oblong asteroid

Quote
On Feb. 3, an asteroid more than three times as long as it is wide safely flew past Earth at a distance of about 1.1 million miles (1.8 million kilometers, or a little under five times the distance between the Moon and Earth). While there was no risk of the asteroid—called 2011 AG5—impacting our planet, scientists at NASA's Jet Propulsion Laboratory in Southern California closely tracked the object, making invaluable observations to help determine its size, rotation, surface details, and, most notably, shape.

https://phys.org/news/2023-02-nasa-planetary-radar-captures-view.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/20/2023 04:27 pm
A CCD Search for Variable Stars in the Open Cluster NGC 6611

We present the results of the UBVIC variability survey in the young open cluster NGC 6611 based on observations obtained during 34 nights spanning one year. In total, we found 95 variable stars. Most of these stars are classified as periodic and irregular pre-main sequence (PMS) stars. The analysis of the JHKS 2MASS photometry and four-colour IRAC photometry revealed 165 Class II young stellar sources, 20 of which are irregular variables and one is an eclipsing binary. These classifications, complemented by JHK UKIDSS photometry and riHα VPHAS photometry, were used to identify 24 candidates for classical T Tauri stars and 30 weak-lined T Tauri stars. In addition to the PMS variables, we discovered eight δ Scuti candidates. None of these were previously known. Furthermore, we detected 17 eclipsing binaries where two were previously known. Based on the proper motions provided by the Gaia EDR3 catalogue, we calculated the cluster membership probabilities for 91 variable stars. For 61 variables, a probability higher than 80% was determined, which makes them cluster members. Only 25 variables with a probability less than 20% were regarded to be non-members.

https://arxiv.org/abs/2302.03628
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/24/2023 06:43 pm
The Thousand-Pulsar-Array program on MeerKAT -- IX. The time-averaged properties of the observed pulsar population

We present the largest single survey to date of average profiles of radio pulsars, observed and processed using the same telescope and data reduction software. Specifically, we present measurements for 1170 pulsars, observed by the Thousand Pulsar Array (TPA) programme at the 64-dish SARAO MeerKAT radio telescope, in a frequency band from 856 to 1712 MHz. We provide rotation measures (RM), dispersion measures, flux densities and polarization properties. The catalogue includes 254 new RMs that substantially increase the total number of known pulsar RMs. Our integration times typically span over 1000 individual rotations per source. We show that the radio (pseudo)luminosity has a strong, shallow dependence on the spin-down energy, proportional to E0.15±0.04, that contradicts some previous proposals of population synthesis studies. In addition, we find a significant correlation between the steepness of the observed flux density spectra and E, and correlations of the fractional linear polarization with E, the spectral index, and the pulse width, which we discuss in the context of what is known about pulsar radio emission and how pulsars evolve with time. On the whole, we do not see significant correlations with the estimated surface magnetic field strength, and the correlations with E are much stronger than those with the characteristic age. This finding lends support to the suggestion that magnetic dipole braking may not be the dominant factor for the evolution of pulsar rotation over the lifetimes of pulsars. A public data release of the high-fidelity time-averaged pulse profiles in full polarization accompanies our catalogue.

https://arxiv.org/abs/2211.11849
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/28/2023 08:32 am
Origin of multiwavelength emission from flaring high redshift blazar PKS 0537-286

The high redhsift blazars powered by supermassive black holes with masses exceeding 109M have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the Universe. We present a multi-frequency spectral and temporal study of high redshift blazar PKS 0537-286 by analyzing data from Fermi-LAT, NuSTAR Swift XRT and UVOT. Although the time averaged γ-ray spectrum of the source is relatively soft (indicating the high-energy emission peak is below the GeV range), several prominent flares were observed when the spectrum hardened and the luminosity increased above 1049ergs−1. The X-ray emission of the source varies in different observations and is characterised by a hard spectrum ≤1.38 with a luminosity of &gt;1047ergs−1. The broadband spectral energy distribution in the quiescent and flaring periods was modeled within a one-zone leptonic scenario assuming different locations of the emission region and considering both internal (synchrotron radiation) and external (from the disk, broad-line region and dusty torus) photon fields for the inverse Compton scattering. The modeling shows that the most optimistic scenario, from the energy requirement point of view, is when the jet energy dissipation occurs within the broad-line region. The comparison of the model parameters obtained for the quiescent and flaring periods suggests that the flaring activities are most likely caused by the hardening of the emitting electron spectral index and shifting of the cut-off energy to higher values.

https://arxiv.org/abs/2302.07682
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2023 04:10 pm
Would have loved to been on this flight.

Pilot circles plane to show passengers northern lights https://www.bbc.co.uk/news/uk-england-manchester-64795572
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2023 04:25 pm
Confirmation of two magnetic cataclysmic variables as polars: 1RXS J174320.1-042953 and YY Sex

We present our analysis of new and archived observations of two candidate magnetic cataclysmic variables, namely 1RXS J174320.1-042953 and YY Sex. 1RXS J174320.1-042953 was observed in two distinctive high and low states where a phase shift was seen, which could be due to the changes in the shape, size, and (or) location of the accretion region. We find that its orbital X-ray modulations only persist in the soft (0.3-2.0 keV) energy band, which could be attributed to the photoelectric absorption in the accretion flow. The X-ray spectra exhibit a multi-temperature post-shock region where the hard X-rays are absorbed through a thick absorber with an equivalent hydrogen column of ∼7.5 × 1023 cm−2, which partially covers ∼56 per cent of the emission. No soft X-ray excess was found to be present; however, a soft X-ray emission with a blackbody temperature of ∼97 eV describes the spectra. Extensive TESS observations of YY Sex allow us to refine its orbital period to 1.5746 ± 0.0011 h. We did not find any signature of previously reported spin or beat periods in this system. Furthermore, our new polarimetric observations show clear circular polarization modulated on the orbital period only. Finally, both systems show strong Balmer and He II 4686 A∘ emission lines in the optical spectra, further indicative of their magnetic nature.

https://arxiv.org/abs/2302.10002
Title: Re: Astronomy & Planetary Science Thread
Post by: M.E.T. on 03/07/2023 08:51 am
Not sure if this is covered in another topic, but I am trying to wrap my mind around the calculation of the size of the universe.

In particular, I don’t understand why we get to an unknown expected difference between the size of the observable universe and the potential size beyond that point - (beyond the cosmological horizon).

If we know the size of the universe at a distant point in the past - at the so called “time of recombination” about 380,000 years after the Big Bang, and we know how much time has passed since then - about 13.8 billion years, and we know the expansion rate of the universe over this period, surely we can calculate the maximum possible size the universe could have expanded into over this time.

It would be X original size, times Y expansion rate,  times Z amount of time. Clearly this is not the case, else the doubt over the distance beyond the cosmological horizon would not exist.

However, if we DID use the above assumptions, what size would we arrive at?

And here I use a flat, finite universe as my basic underlying assumption.
Title: Re: Astronomy & Planetary Science Thread
Post by: LastWyzard on 03/07/2023 01:11 pm
Here is a video by Fermilab's Don Lincoln.  I think it will answer your question about the current size of the observable universe as well as the minimum size of the universe outside the observable portion.

https://www.youtube.com/watch?v=u23vZsJbrjE
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/09/2023 08:13 pm
Asteroid 2023 DW has a very small chance of hitting Earth in 2046:

https://youtu.be/duVIi0WxL3Y
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/10/2023 03:09 pm
Space Rock Slams Into Moon, Explosion seen from Japan!

https://youtu.be/VNjycZDCfcU
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 03/10/2023 08:15 pm
Asteroid 2023 DW has a very small chance of hitting Earth in 2046 ...

It's apparently about 50 meters in diameter. If it does intersect the Earth it will probably explode in the atmosphere. The Chelyabinsk meteor was about 20 meters and exploded with an airburst 30 times the Hiroshima bomb (could be problematic if directly over a city!).

Space Rock Slams Into Moon, Explosion seen from Japan!

Now we don't have to worry about it hitting the Earth (though it would probably have harmlessly burnt up in the atmosphere if it had done so!).
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/13/2023 06:58 pm
Just how ‘real’ are images of the Moon taken with the Samsung Galaxy S23 Ultra:

https://youtu.be/1afpDuTb-P0
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/16/2023 06:00 am
A new study claims that Venus is still volcanically active.

https://www.nationalgeographic.com/science/article/venus-is-volcanically-alive

Edit related video:

https://youtu.be/Xs5CXaTjAwY
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/21/2023 09:18 am
Surprising newfound ocean bacteria could aid search for alien life

Quote
Such hot springs likely also exist on oceanic worlds like Jupiter's moon Europa and the Saturn satellite Enceladus, so these observations sharpen our understanding of the forms alien life might take on those moons, astronomers say.

The newfound bacteria, Sulfurimonas pluma, belongs to a family of organisms that to date had only been known from volcanic vents on Earth's seafloors, as it cannot tolerate high oxygen levels in water elsewhere. So scientists were surprised to find a new member, smaller than its relatives, burgeoning in oxygen-rich water plumes hundreds of meters away from them.

https://www.space.com/newfound-bacteria-aid-search-alien-life
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/23/2023 04:27 pm
Scientists uncover what accelerated an interstellar comet through our solar system

https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: DanClemmensen on 03/23/2023 06:20 pm
Scientists uncover what accelerated an interstellar comet through our solar system

https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html
Articles about 'Oumuamua always bother me because they claim that the object "swept through the Solar system" or some such. In fact the object's velocity was low relative to the average velocity of nearby stars other than Sol. It was more or less just sitting there minding its own business. The Solar system's velocity is higher relative to nearby stars, so Sol "swept by" 'Oumuamua, not the other way around. The interaction kicked the object's velocity up.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/23/2023 07:05 pm
NASA Is Tracking a Huge, Growing Anomaly in Earth's Magnetic Field

Quote
NASA is actively monitoring a strange anomaly in Earth's magnetic field: a giant region of lower magnetic intensity in the skies above the planet, stretching out between South America and southwest Africa.

This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers.

The space agency's satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.

https://www.sciencealert.com/nasa-is-tracking-a-huge-growing-anomaly-in-earths-magnetic-field
Title: Re: Astronomy & Planetary Science Thread
Post by: Blackstar on 03/24/2023 01:59 am
NASA Is Tracking a Huge, Growing Anomaly in Earth's Magnetic Field

Quote
NASA is actively monitoring a strange anomaly in Earth's magnetic field: a giant region of lower magnetic intensity in the skies above the planet, stretching out between South America and southwest Africa.

This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers.

The space agency's satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.

https://www.sciencealert.com/nasa-is-tracking-a-huge-growing-anomaly-in-earths-magnetic-field

Click-bait baloney.

This makes it sound like it's some dangerous "developing phenomenon" that we should be worried about. It was discovered in 1958. NASA has been "tracking" it for 65 years.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/24/2023 10:37 am
NASA Is Tracking a Huge, Growing Anomaly in Earth's Magnetic Field

Quote
NASA is actively monitoring a strange anomaly in Earth's magnetic field: a giant region of lower magnetic intensity in the skies above the planet, stretching out between South America and southwest Africa.

This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers.

The space agency's satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.

https://www.sciencealert.com/nasa-is-tracking-a-huge-growing-anomaly-in-earths-magnetic-field

Click-bait baloney.

This makes it sound like it's some dangerous "developing phenomenon" that we should be worried about. It was discovered in 1958. NASA has been "tracking" it for 65 years.
Guess you didn’t bother actually reading beyond the article headline, as the article itself talks about its evolution over time.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/25/2023 07:30 am
Venus cloud discontinuity in 2022. The first long-term study with uninterrupted observations

https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202244822
Title: Re: Astronomy & Planetary Science Thread
Post by: Comga on 03/25/2023 06:17 pm
Scientists uncover what accelerated an interstellar comet through our solar system

https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html (https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html)
Articles about 'Oumuamua always bother me because they claim that the object "swept through the Solar system" or some such. In fact the object's velocity was low relative to the average velocity of nearby stars other than Sol. It was more or less just sitting there minding its own business. The Solar system's velocity is higher relative to nearby stars, so Sol "swept by" 'Oumuamua, not the other way around. The interaction kicked the object's velocity up.

While the first assertion that “Sol swept by Oumuamua “ is valid, that last statement is not correct.
‘Oumuamua /I1 was observed to be accelerating away from the Sun with no observed water or ion tail as would be expected from an icy comet.
(That periodic comets have a randomness to their return trajectories enabled Fred Whipple to surmise that comets were “dirty snowballs” of ice and dust, with jets of sublimating ice giving erratic pushes away from the Sun.)
Citing that and the extreme shape, evidenced by huge swings in its light curve, and the trajectory that went inside the orbit of Mercury as “targeting”, Dr Avi Loeb of Harvard wrote technical papers and a bestselling book “Extraterrestrial” that posit the best explanation is a tumbling solar sail probe built by … extraterrestrials.
This article posits that I1 was a regular water ice comet, albeit still interstellar, processed by starlight to have an undetectable hydrogen tail.
Loeb and colleague have published a paper with physical arguments that their calculated thrust is high by a factor of three.
YCMV (C=calculations)
There is another paper suggesting that ‘Oumaumau is a solid hydrogen iceberg, and how that could be formed and maintained with a sublimation temperature below the temperature of the cosmic microwave background. It discussed how irregularities in the initial shape would amplify as it sublimated, like a bar of soap gets very thin towards its end.
Another paper supports the idea that it is an iceberg of solid nitrogen, from which a cometary tail also would not have been observed. (This is my favorite explanation because we have in fact seen icebergs of solid nitrogen, … on Pluto!)
Dr Karen Meech, an authority on comets, has said (published?) that it could still have been an icy comet whose tail was just below the threshold of detection for the few observations that were made before it flew back into the interstellar darkness.

(Apologies for not hypertext linking all those references but that would take me days.)

Edit: Duh!  Book title!
Title: Re: Astronomy & Planetary Science Thread
Post by: DanClemmensen on 03/25/2023 07:59 pm
Scientists uncover what accelerated an interstellar comet through our solar system

https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html (https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html)
Articles about 'Oumuamua always bother me because they claim that the object "swept through the Solar system" or some such. In fact the object's velocity was low relative to the average velocity of nearby stars other than Sol. It was more or less just sitting there minding its own business. The Solar system's velocity is higher relative to nearby stars, so Sol "swept by" 'Oumuamua, not the other way around. The interaction kicked the object's velocity up.
While the first assertion that “Sol swept by Oumuamua “ is valid, that last statement is not correct.
   <snip other accelerations...>
I did not mean to say that there were no other accelerations. However, by far the largest acceleration was the gravity sling caused by  'Oumuamua's hyperbolic orbit with respect to Sol. To find those other tiny accelerations, the astronomers must first subtract out the huge gravitational effect.
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 03/27/2023 05:15 pm
Scientists uncover what accelerated an interstellar comet through our solar system

https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html (https://edition.cnn.com/2023/03/23/world/oumuamua-interstellar-comet-scn/index.html)
Articles about 'Oumuamua always bother me because they claim that the object "swept through the Solar system" or some such. In fact the object's velocity was low relative to the average velocity of nearby stars other than Sol. It was more or less just sitting there minding its own business. The Solar system's velocity is higher relative to nearby stars, so Sol "swept by" 'Oumuamua, not the other way around. The interaction kicked the object's velocity up.

While the first assertion that “Sol swept by Oumuamua “ is valid, that last statement is not correct.
‘Oumuamua /I1 was observed to be accelerating away from the Sun with no observed water or ion tail as would be expected from an icy comet.
(That periodic comets have a randomness to their return trajectories enabled Fred Whipple to surmise that comets were “dirty snowballs” of ice and dust, with jets of sublimating ice giving erratic pushes away from the Sun.)
Citing that and the extreme shape, evidenced by huge swings in its light curve, and the trajectory that went inside the orbit of Mercury as “targeting”, Dr Avi Loeb of Harvard wrote technical papers and a bestselling book “Extraterrestrial” that posit the best explanation is a tumbling solar sail probe built by … extraterrestrials.
This article posits that I1 was a regular water ice comet, albeit still interstellar, processed by starlight to have an undetectable hydrogen tail.
Loeb and colleague have published a paper with physical arguments that their calculated thrust is high by a factor of three.
YCMV (C=calculations)
There is another paper suggesting that ‘Oumaumau is a solid hydrogen iceberg, and how that could be formed and maintained with a sublimation temperature below the temperature of the cosmic microwave background. It discussed how irregularities in the initial shape would amplify as it sublimated, like a bar of soap gets very thin towards its end.
Another paper supports the idea that it is an iceberg of solid nitrogen, from which a cometary tail also would not have been observed. (This is my favorite explanation because we have in fact seen icebergs of solid nitrogen, … on Pluto!)
Dr Karen Meech, an authority on comets, has said (published?) that it could still have been an icy comet whose tail was just below the threshold of detection for the few observations that were made before it flew back into the interstellar darkness.

(Apologies for not hypertext linking all those references but that would take me days.)

Edit: Duh!  Book title!

Always bugs me that these other likely reasons for its acceleration are never mentioned. I suppose only the crazy stuff makes news though
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/28/2023 11:02 pm
Space scientists reveal brightest gamma explosion ever https://www.bbc.co.uk/news/uk-england-leicestershire-65104115
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/29/2023 06:30 pm
Discovery of a massive giant planet with extreme density around a sub-giant star TOI-4603

We present the discovery of a transiting massive giant planet around TOI-4603, a sub-giant F-type star from NASA's Transiting Exoplanet Survey Satellite (TESS). The newly discovered planet has a radius of 1.042+0.038−0.035 RJ, and an orbital period of 7.24599+0.00022−0.00021 days. Using radial velocity measurements with the PARAS {and TRES} spectrographs, we determined the planet's mass to be 12.89+0.58−0.57 MJ, resulting in a bulk density of 14.1+1.7−1.6 g cm−3. This makes it one of the few massive giant planets with extreme density and lies in the transition mass region of massive giant planets and low-mass brown dwarfs, an important addition to the population of less than five objects in this mass range. The eccentricity of 0.325±0.020 and an orbital separation of 0.0888±0.0010 AU from its host star suggest that the planet is likely undergoing high eccentricity tidal (HET) migration. We find a fraction of heavy elements of 0.13+0.05−0.06 and metal enrichment of the planet (ZP/Zstar) of 4.2+1.6−2.0. Detection of such systems will offer us to gain valuable insights into the governing mechanisms of massive planets and improve our understanding of their dominant formation and migration mechanisms.

https://arxiv.org/abs/2303.11841#
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/30/2023 05:27 pm
Largest black hole found yet revealed through gravitational lensing:

https://youtu.be/4lO06LHjrA4

An astonishing 30 billion solar masses.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/02/2023 07:37 pm
‘Unique’ black hole that’s only 3800 light-years away discovered by Gaia:

https://youtu.be/WivyGW4-lE8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/04/2023 03:46 pm
A Large Double-ring Disk around the Taurus M Dwarf J04124068+2438157

Planet formation imprints signatures on the physical structures of disks. In this paper, we present high-resolution (∼50 mas, 8 au) Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.3 mm dust continuum and CO line emission toward the disk around the M3.5 star 2MASS J04124068+2438157. The dust disk consists only of two narrow rings at radial distances of 0.47 and 0.78 arcsec (∼70 and 116 au), with Gaussian σ widths of 5.6 and 8.5 au, respectively. The width of the outer ring is smaller than the estimated pressure scale height by ∼25%, suggesting dust trapping in a radial pressure bump. The dust disk size, set by the location of the outermost ring, is significantly larger (by 3σ) than other disks with similar millimeter luminosity, which can be explained by an early formation of local pressure bump to stop radial drift of millimeter dust grains. After considering the disk's physical structure and accretion properties, we prefer planet--disk interaction over dead zone or photoevaporation models to explain the observed dust disk morphology. We carry out high-contrast imaging at L′ band using Keck/NIRC2 to search for potential young planets, but do not identify any source above 5σ. Within the dust gap between the two rings, we reach a contrast level of ∼7 mag, constraining the possible planet below ∼2--4 MJup. Analyses of the gap/ring properties suggest a ∼Saturn mass planet at ∼90 au is likely responsible for the formation of the outer ring, which can be potentially revealed with JWST.

https://arxiv.org/abs/2303.14586#
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/05/2023 04:20 pm
Lunar eclipses illuminate timing and climate impact of medieval volcanism

Abstract
Explosive volcanism is a key contributor to climate variability on interannual to centennial timescales1. Understanding the far-field societal impacts of eruption-forced climatic changes requires firm event chronologies and reliable estimates of both the burden and altitude (that is, tropospheric versus stratospheric) of volcanic sulfate aerosol2,3. However, despite progress in ice-core dating, uncertainties remain in these key factors4. This particularly hinders investigation of the role of large, temporally clustered eruptions during the High Medieval Period (HMP, 1100–1300 CE), which have been implicated in the transition from the warm Medieval Climate Anomaly to the Little Ice Age5. Here we shed new light on explosive volcanism during the HMP, drawing on analysis of contemporary reports of total lunar eclipses, from which we derive a time series of stratospheric turbidity. By combining this new record with aerosol model simulations and tree-ring-based climate proxies, we refine the estimated dates of five notable eruptions and associate each with stratospheric aerosol veils. Five further eruptions, including one responsible for high sulfur deposition over Greenland circa 1182 CE, affected only the troposphere and had muted climatic consequences. Our findings offer support for further investigation of the decadal-scale to centennial-scale climate response to volcanic eruptions.

https://www.nature.com/articles/s41586-023-05751-z
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/07/2023 02:03 pm
A hard look at the X-ray spectral variability of NGC 7582

NGC 7582 (z = 0.005264; D = 22.5 Mpc) is a highly variable, changing-look AGN. In this work, we explore the X-ray properties of this source using XMM-Newton and NuSTAR archival observations in the 3-40 keV range, from 2001 to 2016. NGC 7582 exhibits a long-term variability between observations but also a short-term variability in two observations that has not been studied before. To study the variability, we perform a time-resolved spectral analysis using a phenomenological model and a physically-motivated model (uxclumpy). The spectral fitting is achieved using a nested sampling Monte Carlo method. uxclumpy enables testing various geometries of the absorber that may fit AGN spectra. We find that the best model is composed of a fully covering clumpy absorber. From this geometry, we estimate the velocity, size and distance of the clumps. The column density of the absorber in the line of sight varies from Compton-thin to Compton-thick between observations. Variability over the timescale of a few tens of kilo-seconds is also observed within two observations. The obscuring clouds are consistent with being located at a distance not larger than 0.6 pc, moving with a transverse velocity exceeding ∼700 km s−1. We could put only a lower limit on the size of the obscuring cloud being larger than 1013 cm. Given the sparsity of the observations, and the limited exposure time per observation available, we cannot determine the exact structure of the obscuring clouds. The results are broadly consistent with comet-like obscuring clouds or spherical clouds with a non-uniform density profile.

https://arxiv.org/abs/2303.17473#
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/10/2023 06:34 pm
Vertical wind structure in an X-ray binary revealed by a precessing accretion disk

Abstract
The accretion of matter onto black holes and neutron stars often leads to the launching of outflows that can greatly affect the environments surrounding the compact object. An important means of studying these winds is through X-ray absorption line spectroscopy, which allows us to probe their properties along a single sightline, but usually provides little information about the global three-dimensional wind structure, which is vital for understanding the launching mechanism and total wind energy budget. Here, we study Hercules X-1, a nearly edge-on X-ray binary with a warped accretion disk precessing with a period of about 35 d. This disk precession results in changing sightlines towards the neutron star, through the ionized outflow. We perform time-resolved X-ray spectroscopy over the precession phase and detect a strong decrease in the wind column density by three orders of magnitude as our sightline progressively samples the wind at greater heights above the accretion disk. The wind becomes clumpier as it rises upwards and expands away from the neutron star. Modelling the warped disk shape, we create a two-dimensional map of wind properties. This measurement of the vertical structure of an accretion disk wind allows direct comparisons with three-dimensional global simulations to reveal the outflow launching mechanism.

https://www.nature.com/articles/s41550-023-01929-7
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/12/2023 05:05 pm
The Apertif Radio Transient System (ARTS): Design, commissioning, data release, and detection of the first five fast radio bursts

Abstract
Fast radio bursts (FRBs) must be powered by uniquely energetic emission mechanisms. This requirement has eliminated a number of possible source types, but several remain. Identifying the physical nature of FRB emitters arguably requires good localisation of more detections, as well as broad-band studies enabled by real-time alerting. In this paper, we present the Apertif Radio Transient System (ARTS), a supercomputing radio-telescope instrument that performs real-time FRB detection and localisation on the Westerbork Synthesis Radio Telescope (WSRT) interferometer. It reaches coherent-addition sensitivity over the entire field of the view of the primary-dish beam. After commissioning results verified that the system performed as planned, we initiated the Apertif FRB survey (ALERT). Over the first 5 weeks we observed at design sensitivity in 2019, we detected five new FRBs, and interferometrically localised each of them to 0.4–10 sq. arcmin. All detections are broad band, very narrow, of the order of 1 ms in duration, and unscattered. Dispersion measures are generally high. Only through the very high time and frequency resolution of ARTS are these hard-to-find FRBs detected, producing an unbiased view of the intrinsic population properties. Most localisation regions are small enough to rule out the presence of associated persistent radio sources. Three FRBs cut through the halos of M31 and M33. We demonstrate that Apertif can localise one-off FRBs with an accuracy that maps magneto-ionic material along well-defined lines of sight. The rate of one every ~7 days ensures a considerable number of new sources are detected for such a study. The combination of the detection rate and localisation accuracy exemplified by the first five ARTS FRBs thus marks a new phase in which a growing number of bursts can be used to probe our Universe.

https://www.aanda.org/articles/aa/full_html/2023/04/aa44107-22/aa44107-22.html

Related video:

https://youtu.be/3DgVFq_nsv4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/13/2023 06:16 am
Confirmation and Keplerian motion of the gap-carving protoplanet HD 169142 b

ABSTRACT
We present the re-detection of a compact source in the face-on protoplanetary disc surrounding HD 169142, using VLT/SPHERE data in YJH bands. The source is found at a separation of 0′′.319 (∼37 au) from the star. Three lines of evidence argue in favour of the signal tracing a protoplanet: (i) it is found in the annular gap separating the two bright rings of the disc, as predicted by theory; (ii) it is moving at the expected Keplerian velocity for an object at ∼37 au in the 2015, 2017, and 2019 data sets; and (iii) we also detect a spiral-shaped signal whose morphology is consistent with the expected outer spiral wake triggered by a planet in the gap, based on dedicated hydrodynamical simulations of the system. The YJH colours we extracted for the object are consistent with tracing scattered starlight, suggesting that the protoplanet is enshrouded in a significant amount of dust, as expected for a circumplanetary disc or envelope surrounding a gap-clearing Jovian-mass protoplanet.

https://academic.oup.com/mnrasl/article/522/1/L51/7070740

Related video:

https://youtu.be/Uxsk3TE_3L4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/13/2023 07:25 pm
First-ever black hole image ‘sharpened’ using machine learning:

https://youtu.be/41ESgja-d2w
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 04/13/2023 07:30 pm
Cool Worlds looking at do galactic habitable zones exist as dictated by rates of GRBS, supernova, planet formation and retention  - An event so EXTREME it Makes Parts of the Galaxy Uninhabitable:

https://youtu.be/M7PM8iDt_4w
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/13/2023 08:43 pm
Direct imaging and astrometric detection of a gas giant planet orbiting an accelerating star

Abstract

Direct imaging of gas giant exoplanets provides information on their atmospheres and the architectures of planetary systems. However, few planets have been detected in blind surveys with direct imaging. Using astrometry from the Gaia and Hipparcos spacecraft, we identified dynamical evidence for a gas giant planet around the nearby star HIP 99770. We confirmed the detection of this planet with direct imaging using the Subaru Coronagraphic Extreme Adaptive Optics instrument. The planet, HIP 99770 b, orbits 17 astronomical units from its host star, receiving an amount of light similar to that reaching Jupiter. Its dynamical mass is 13.9 to 16.1 Jupiter masses. The planet-to-star mass ratio [(7 to 8) × 10−3] is similar to that of other directly imaged planets. The planet’s atmospheric spectrum indicates an older, less cloudy analog of the previously imaged exoplanets around HR 8799.

https://www.science.org/doi/10.1126/science.abo6192
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/25/2023 04:44 pm
UVIT view of NGC 5291: Ongoing star formation in tidal dwarf galaxies at ∼ 0.35 kpc resolution

ABSTRACT
NGC 5291, an early-type galaxy surrounded by a giant H I ring, is believed to be formed from collision with another galaxy. Several star forming complexes and tidal dwarf galaxies are distributed along the collisional ring which are sites of star formation in environments where extreme dynamical effects are involved. Dynamical effects can affect the star formation properties and the spatial distribution of star forming complexes along the tidal features. To study and quantify the star formation activity in the main body and in the ring structure of the NGC 5291 system, we use high spatial resolution FUV and NUV imaging observations from the Ultraviolet Imaging Telescope onboard AstroSat. A total of 57 star-forming knots are identified to be part of this interacting system out of which 12 are new detections (star forming complexes that lie inside the H I contour) compared to the previous measurements from lower resolution UV imaging. We estimate the attenuation in UV for each of the resolved star-forming knots using the UV spectral slope β, derived from the FUV − NUV colour. Using the extinction corrected UV fluxes, we derive the star formation rate of the resolved star forming complexes. The extinction corrected total star formation rate of this system is estimated as 1.75 ± 0.04 M⊙yr−1⁠. The comparison with dwarf galaxy populations (BCD, Sm, and dIm galaxies) in the nearby Universe shows that many of the knots in the NGC 5291 system have SFR values comparable to the SFR of BCD galaxies.

https://academic.oup.com/mnras/article-abstract/522/1/1196/7110422
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/26/2023 04:44 pm
First image of a black hole expelling a powerful jet (ESOcast 260 Light)

https://youtu.be/4prdUmf5EsA
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/27/2023 07:01 pm
Detection of millihertz quasi-periodic oscillations in the low-mass X-ray binary 4U 1730–22 with NICER

ABSTRACT
We report the discovery of millihertz quasi-periodic oscillations (mHz QPOs) from the neutron star (NS) low-mass X-ray binary 4U 1730–22 using the Neutron Star Interior Composition Explorer (NICER). After being inactive for almost 50 years, 4U 1730–22 went into outburst twice between June and August 2021, and between February and July 2022. We analyse all the NICER observations of this source, and detect mHz QPOs with a significance > 4 σ in 35 observations. The QPO frequency of the full data set ranged between ∼ 4.5 and ∼ 8.1 mHz with an average fractional rms amplitude of the order of ∼2 per cent. The X-ray colour analysis strongly suggests that 4U 1730–22 was in a soft spectral state during the QPO detections. Our findings are consistent with those reported for other sources where the mHz QPOs have been interpreted as the result of a special mode of He burning on the NS surface called marginally stable nuclear burning (MSNB). We conclude that the mHz QPOs reported in this work are also associated with the MSNB, making 4U 1730–22 the eighth source that shows this phenomenology. We discuss our findings in the context of the heat flux from the NS crust.

https://academic.oup.com/mnras/article-abstract/521/4/5616/7093415
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 04/28/2023 04:42 pm
Detection of a High-velocity Prominence Eruption Leading to a CME Associated with a Superflare on the RS CVn-type Star V1355 Orionis

Abstract
Stellar coronal mass ejections (CMEs) have recently received much attention for their impacts on exoplanets and stellar evolution. Detecting prominence eruptions, the initial phase of CMEs, as the blueshifted excess component of Balmer lines is a technique to capture stellar CMEs. However, most of prominence eruptions identified thus far have been slow and less than the surface escape velocity. Therefore, whether these eruptions were developing into CMEs remained unknown. In this study, we conducted simultaneous optical photometric observations with Transiting Exoplanet Survey Satellite and optical spectroscopic observations with the 3.8 m Seimei Telescope for the RS CVn-type star V1355 Orionis that frequently produces large-scale superflares. We detected a superflare releasing 7.0 × 1035 erg. In the early stage of this flare, a blueshifted excess component of Hα extending its velocity up to 760–1690 km s−1 was observed and thought to originate from prominence eruptions. The velocity greatly exceeds the escape velocity (i.e., ∼350 km s−1), which provides important evidence that stellar prominence eruptions can develop into CMEs. Furthermore, we found that the prominence is very massive (9.5 × 1018 g &lt; M &lt; 1.4 × 1021 g). These data will clarify whether such events follow existing theories and scaling laws on solar flares and CMEs even when the energy scale far exceeds solar cases.

https://iopscience.iop.org/article/10.3847/1538-4357/acb7e8
Title: Re: Astronomy & Planetary Science Thread
Post by: sanman on 04/29/2023 01:46 pm
https://phys.org/news/2023-04-ai-planet-solar.html

Quote
Researchers Use AI to Discover New Planet Outside Solar System

A University of Georgia research team has confirmed evidence of a previously unknown planet outside of our solar system, and they used machine learning tools to detect it.

A recent study by the team showed that machine learning can correctly determine if an exoplanet is present by looking in protoplanetary disks, the gas around newly formed stars.

The newly published findings in The Astrophysical Journal represent a first step toward using machine learning to identify previously overlooked exoplanets.

...
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/03/2023 02:15 pm
Study using X-Ray telescope indicates that dark energy is uniformly distributed in space and time

https://phys.org/news/2023-05-x-ray-telescope-dark-energy-uniformly.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/03/2023 02:36 pm
Observing the ashes of the first stars (ESOcast 261 Light)

https://youtu.be/dtaym_H-F1A
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/03/2023 05:00 pm
Quote
Astronomers have conducted photometric observations of a white dwarf known as J004917.14−252556.81. Results of the observational campaign detected photometric variability of this object, making J004917.14−252556.81 the most massive pulsating white dwarf known to date. The finding is reported in a paper published April 18 in Monthly Notices of the Royal Astronomical Society.

https://phys.org/news/2023-05-j00492525-massive-pulsating-white-dwarf.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Larry Golo on 05/08/2023 04:20 pm
This paper is amazing. Completely blew my mind.

The title alone sounds like an hommage to the late Douglas Adams  8)

The cosmic hitchhikers hypothesis: extraterrestrial civilizations using free-floating planets for interstellar colonization

E.Ts land their ships on rogue planets and hitch free rides. Even if the ride is slow (250 million years to circle the galaxy only once) and not very... steerable, the basic concept is profound, far reaching, and pretty exciting.

By the way, for 200 billion stars in the Milky Way, there might be 0.25 to ... 10 000 times that number of free floating planet hanging around. In fact planets not bound to any star might dominate planetary numbers by a wide margin.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/11/2023 06:32 pm
Quote
An international team of astronomers reports the discovery of a new enigmatic galaxy system as part of the DESI Legacy Imaging Surveys. The newfound system consists of a pair of galaxies and an extended highly collimated tail of gas and stars. The finding was reported May 2 on the arXiv pre-print server.

https://phys.org/news/2023-05-astronomers-unusual-galaxy-highly-collimated.html

Related paper:

https://arxiv.org/abs/2305.01335
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/12/2023 06:33 am
Quote
Hot air balloons launched by scientists have recorded mysterious sounds of “completely unknown” origin, high in the Earth’s atmosphere.

Large 6-7-metre-long balloons were sent to the stratosphere – the relatively calm layer of Earth’s atmosphere which is rarely disturbed by planes or turbulence – by researchers, including Daniel Bowman of Sandia National Laboratories in the US.

Quote
While the balloons could detect such human and environmental sounds, researchers reported in a presentation at the 184th Meeting of the Acoustical Society of America, that they also managed to record some strange sounds that could not be identified.

“[In the stratosphere] there are mysterious infrasound signals that occur a few times per hour on some flights, but the source of these is completely unknown,” Dr Bowman said in a statement.

https://www.independent.co.uk/space/stratosphere-mysterious-sound-balloon-record-b2337455.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/15/2023 04:36 pm
Quote
Using NASA's Swift observatory and ESA's XMM-Newton satellite, Indian astronomers have inspected a prominent high synchrotron peaked blazar known as 1ES 1959+650. Results of the study, published May 5 on the arXiv pre-print server, shed more light on the nature of this source.

https://phys.org/news/2023-05-blazar-1es-swift-xmm-newton-satellites.html

Related paper:

https://arxiv.org/abs/2305.03246
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/16/2023 06:35 pm
Betelgeuse has been brightening up again of late.

https://www.scientificamerican.com/article/betelgueses-brightening-raises-hopes-for-a-supernova-spectacle/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/17/2023 01:52 pm
Quote
Using the MeerKAT radio telescope, European astronomers have serendipitously discovered a new radio nebula during observations of the black hole binary GRS 1915+105. The newfound object, dubbed "the Mini Mouse," is a young radio pulsar escaping its birth site and therefore creating a radio nebula with a cometary-like morphology. The finding was reported in a paper published May 10 on the arXiv preprint server.

https://phys.org/news/2023-05-meerkat-radio-telescope-mini-mouse.html

Related paper:

https://arxiv.org/abs/2305.06130
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/21/2023 07:27 am
The Milky Way galaxy may be a different shape than we thought

Quote
New measurements suggest that the Milky Way galaxy may have a different shape than we thought.

Quote
This led the astronomers to suggest that the Milky Way is a barred spiral galaxy with just two main arms extending from this dense central bar.

https://www.space.com/milky-way-galaxy-different-shape

Related paper:

Quote
Abstract
In spite of much work, the overall spiral structure morphology of the Milky Way remains somewhat uncertain. In the last two decades, accurate distance measurements have provided us with an opportunity to solve this issue. Using the precise locations of very young objects, for the first time, we propose that our galaxy has a multiple-arm morphology that consists of two-arm symmetry (the Perseus and Norma Arms) in the inner parts and that extends to the outer parts, where there are several long, irregular arms (the Centaurus, Sagittarius, Carina, Outer, and Local Arms).

https://iopscience.iop.org/article/10.3847/1538-4357/acc45c
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 05/23/2023 11:07 pm
First observational indication of a so called Boson star?

https://www.livescience.com/space/black-holes/strange-star-system-may-hold-first-evidence-of-an-ultra-rare-dark-matter-star

Related paper:

A Sun-like star orbiting a boson star

The high-precision astrometric mission GAIA recently reported the remarkable discovery of a Sun-like star closely orbiting a dark object, with a semi-major axis and period of 1.4AU and 187.8 days respectively. While the plausible expectation for the central dark object is a black hole, the evolutionary mechanism leading to the formation of such a two-body system is highly challenging. Here, we challenge the scenario of a central black hole and show that the observed orbital dynamics can be explained under fairly general assumptions if the central dark object is a stable clump of bosonic particles of spin-0, or spin-1, known as a boson star. We further explain how future astrometric measurements of similar systems will provide an exciting opportunity to probe the fundamental nature of compact objects and test compact alternatives to black holes.

https://arxiv.org/abs/2304.09140
Title: Re: Astronomy & Planetary Science Thread
Post by: matthewkantar on 05/24/2023 01:55 am
First observational indication of a so called Boson star?

https://www.livescience.com/space/black-holes/strange-star-system-may-hold-first-evidence-of-an-ultra-rare-dark-matter-star

Related paper:

A Sun-like star orbiting a boson star

The high-precision astrometric mission GAIA recently reported the remarkable discovery of a Sun-like star closely orbiting a dark object, with a semi-major axis and period of 1.4AU and 187.8 days respectively. While the plausible expectation for the central dark object is a black hole, the evolutionary mechanism leading to the formation of such a two-body system is highly challenging. Here, we challenge the scenario of a central black hole and show that the observed orbital dynamics can be explained under fairly general assumptions if the central dark object is a stable clump of bosonic particles of spin-0, or spin-1, known as a boson star. We further explain how future astrometric measurements of similar systems will provide an exciting opportunity to probe the fundamental nature of compact objects and test compact alternatives to black holes.

https://arxiv.org/abs/2304.09140

This seems like a huge reach to me. LIGO has detected the ends of dozens of black holes under ten solar masses. Occam says no to this, imo, but wow! if this holds up.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 05/26/2023 06:24 am
Quote
According to new observations detailed in a paper published in Geophysical Research Letters, Uranus most likely has a polar vortex swirling around its north pole, too. These types of cyclones have been observed on almost every other planet in our solar system, save for Mercury, which NASA explains has no “substantial” atmosphere, making it impossible to form a vortex.

https://bgr.com/science/uranus-may-be-more-active-than-scientists-previously-believed/

Related paper:

Evidence of a Polar Cyclone on Uranus From VLA Observations

Abstract
We present observations of Uranus in northern spring with the Very Large Array from 0.7 to 5 cm. These observations reveal details in thermal emission from Uranus' north pole at 10s of bars, including a dark collar near 80°N and a bright spot at the polar center. The bright central spot resembles observations of polar emission on Saturn and Neptune at shallower pressures. We constrain the variations in temperature and NH3/H2S abundances which could explain these features. We find that the brightness temperature of the polar spot can be recreated through 5 K temperature gradients and/or 10× depletion of NH3 or H2S vapor between 10 and 20 bars, both consistent with the presence of a cyclonic polar vortex. The contrast of the polar spot may have increased since 2015, which would suggest seasonal evolution of Uranus' polar circulation at depth.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL102872
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/01/2023 04:29 pm
Quote
An international team of astronomers reports the detection of a new, hot-dust-obscured galaxy (DOG). The galaxy, which received designation WISE J190445.04+485308.9, was found at a relatively low redshift of 0.415, which makes it the first confirmed low-redshift hot DOG. The discovery was presented in a paper published May 23 on the arXiv preprint server.

https://phys.org/news/2023-06-hot-dog-sky-astronomers-hot-dust-obscured.html

Related paper:

https://arxiv.org/abs/2305.13739
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/05/2023 03:57 pm
Quote
Using NASA's Neil Gherels Swift Observatory, Indian astronomers have observed a blazar known as OJ 287. Results of the observational campaign, published May 25 on the arXiv pre-print server, shed more light on the spectral changes of OJ 287, improving our knowledge about the behavior of this source.

https://phys.org/news/2023-06-spectral-blazar-oj.html

Related paper:

https://arxiv.org/abs/2305.16144
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/06/2023 04:28 pm
Quote
Using NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers have discovered a new "warm Jupiter" exoplanet. The newfound alien world, designated TOI-1859 b, orbits its parent star on an eccentric and misaligned orbit. The finding is reported in a paper published May 25 on the arXiv preprint server.

https://phys.org/news/2023-06-astronomers-jupiter-eccentric-misaligned-orbit.html

Related paper:

https://arxiv.org/abs/2305.16495
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/07/2023 04:54 pm
Quote
Using the Hard X-ray Modulation Telescope (HXMT) and the Neutron star Interior Composition Explorer (NICER), astronomers from China and India have observed two X-ray binaries known as GX 339−4 and EXO 1846−031. Results of the observational campaign, published May 29 on the arXiv pre-print repository, reveal essential information regarding the evolution of quasi-periodic oscillations (QPOs) identified in these systems.

https://phys.org/news/2023-06-explore-evolution-quasi-periodic-oscillations-x-ray.html

Related paper:

https://arxiv.org/abs/2305.18249
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/08/2023 03:41 pm
Researchers detect elusive planets with CHEOPS

Quote
With the help of the CHEOPS space telescope an international team of European astronomers managed to clearly identify the existence of four new exoplanets. The four mini-Neptunes are smaller and cooler, and more difficult to find than the so-called Hot Jupiter exoplanets which have been found in abundance. Two of the four resulting papers are led by researchers from the University of Bern and the University of Geneva who are also members of the National Centre of Competence in Research (NCCR) PlanetS.

https://phys.org/news/2023-06-elusive-planets-cheops.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/12/2023 04:07 pm
Quote
An international team of astronomers has announced the second-ever discovery of a multiplanetary circumbinary system.

Circumbinary systems contain planets that orbit around two stars in the center instead of just one, like in our solar system. Circumbinary planets orbit around both stars at once. The discovery, led by researchers at the University of Birmingham, is reported in the journal Nature Astronomy.

The newly discovered planet is called BEBOP-1c, after the name of the project that collected the data. BEBOP stands for Binaries Escorted By Orbiting Planets. The BEBOP-1 system is also known as TOI-1338.

https://phys.org/news/2023-06-tatooine-like-multi-planetary.html

Related paper:

https://www.nature.com/articles/s41550-023-01948-4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/13/2023 06:15 am
Quote
An international team of astronomers reports the detection of 12 new long-rising Type II supernovae as part of the Zwicky Transient Facility (ZTF) Census of the Local Universe (CLU). The discovery, published June 1 on the arXiv pre-print repository, nearly doubles the number of known supernovae of this subclass.

https://phys.org/news/2023-06-astronomers-long-rising-ii-supernovae.html

Related paper:

https://arxiv.org/abs/2306.01109
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/13/2023 04:30 pm
Quote
Using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), astronomers from the Purple Mountain Observatory (PMO) in Nanjing, China, have observed a pulsar known as RRAT J1913+1330. Results of the observational campaign, published June 5 on the arXiv pre-print server, indicate that it is an extremely variable pulsar with peculiar properties.

https://phys.org/news/2023-06-rrat-j19131330-extremely-variable-pulsar.html

Related paper:

https://arxiv.org/abs/2306.02855
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/14/2023 04:31 pm
Quote
By conducting Varstrometry for Off-nucleus and Dual sub-Kpc AGN (VODKA), astronomers from the University of Illinois at Urbana-Champaign and elsewhere, have investigated a quasar known as SDSS J0823+2418. The study, published June 6 on the pre-print server arXiv, yields important insights into the true nature of this quasar.

https://phys.org/news/2023-06-astronomers-true-nature-quasar-sdss.html

Related paper:

https://arxiv.org/abs/2306.04041
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/14/2023 07:53 pm
https://twitter.com/latestinspace/status/1669052557602217994?

Quote
BREAKING : Scientists have found phosphorous, a key building block of life, in an ocean on Saturn's moon Enceladus

It's the first time the element has been found outside of Earth

Quote
The search for extraterrestrial life in our solar system just got more exciting. A team of scientists including Southwest Research Institute's Dr. Christopher Glein has discovered new evidence that the subsurface ocean of Saturn's moon Enceladus contains a key building block for life. The team directly detected phosphorus in the form of phosphates originating from the moon's ice-covered global ocean using data from NASA's Cassini mission. Cassini explored Saturn and its system of rings and moons for over 13 years.

https://phys.org/news/2023-06-key-block-life-saturn-moon.amp

Here’s the paper in Nature:

https://www.nature.com/articles/s41586-023-05987-9
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/14/2023 09:22 pm
Quote
It's the first time the element has been found outside of Earth

Here’s the paper in Nature:

https://www.nature.com/articles/s41586-023-05987-9

Here's the problem with clickbaity websites that just try (and usually fail) to promote contents they don't contribute to, and usually don't understand, in the first place.

The bolded -and bold- statement is, trivially and almost obviously, completely wrong. Of course phosphorous has been detected outside Earth, like most elements, in different chemical forms. Go no further than in the spectra of most stars.

If we're talking about direct detection (as in sampling of actual material), it has also been detected in-situ on Mars by the MERs: https://www.hou.usra.edu/meetings/lpsc2015/pdf/2850.pdf , in the Venusian atmosphere by the VeGa probes https://www.liebertpub.com/doi/10.1089/ast.2020.2267 , in comets like 67P by Rosetta https://arxiv.org/pdf/2010.13379.pdf , and abundantly on our Moon, both in-situ and in returned samples. I'm sure I'm leaving out other places as well.

Now, going to the Nature article and reading no further than the fifth line, shows where the above editors switched off their brains in transcribing the finding: "Phosphorus, the least abundant of the bio-essential elements, has not yet been detected in an ocean beyond Earth". They must have thought: sure, go ahead and cut out those words if you're running out of characters.

Furthermore, the substance detected were sodium phosphates (it's actually the third word in the Nature article, after "Detection of"), not elemental phosphorus as the poorly written tweet suggests.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 06/14/2023 11:32 pm
Quote
It's the first time the element has been found outside of Earth

Here’s the paper in Nature:

https://www.nature.com/articles/s41586-023-05987-9

Here's the problem with clickbaity websites that just try (and usually fail) to promote contents they don't contribute to, and usually don't understand, in the first place.

The bolded -and bold- statement is, trivially and almost obviously, completely wrong. Of course phosphorous has been detected outside Earth, like most elements, in different chemical forms. Go no further than in the spectra of most stars.

If we're talking about direct detection (as in sampling of actual material), it has also been detected in-situ on Mars by the MERs: https://www.hou.usra.edu/meetings/lpsc2015/pdf/2850.pdf , in the Venusian atmosphere by the VeGa probes https://www.liebertpub.com/doi/10.1089/ast.2020.2267 , in comets like 67P by Rosetta https://arxiv.org/pdf/2010.13379.pdf , and abundantly on our Moon, both in-situ and in returned samples. I'm sure I'm leaving out other places as well.

Now, going to the Nature article and reading no further than the fifth line, shows where the above editors switched off their brains in transcribing the finding: "Phosphorus, the least abundant of the bio-essential elements, has not yet been detected in an ocean beyond Earth". They must have thought: sure, go ahead and cut out those words if you're running out of characters.

Furthermore, the substance detected were sodium phosphates (it's actually the third word in the Nature article, after "Detection of"), not elemental phosphorus as the poorly written tweet suggests.
Hence why I posted the paper, I can remove the tweet from the post if you feel it’s that misleading?
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/15/2023 12:40 pm
It's not so much an issue with your post (although I personally wouldn't have linked that clickbaity, poorly sourced, misleading "science" tabloid even if I'd first stumbled upon the article there for the first time, FWIW), as with these accounts that scrap content off solid sources to gain notoriety through minimal work.

In fact, the tweet doesn't even provide a source (it does in the "correction" under it, instead of correcting/reposting the offending claim), like the vast majority of their feed, and uses a misleading picture of microbes to go with it, arrow to the moon's plumes and all. They weren't far from just claiming life on Enceladus - in fact they go awfully close in other recent tweet ("Enceladus now has a habitable ocean" ffs...) I just have a profound distaste for these parasites drowning out the Internet nowadays, for profit then. Have you tried googling for a source lately? It's either hacker-level mastery of the search algorithms, or pages upon pages of second-hand reports, usually inaccurate and identically plain.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/15/2023 02:16 pm
It's not so much an issue with your post (although I personally wouldn't have linked that clickbaity, poorly sourced, misleading "science" tabloid even if I'd first stumbled upon the article there for the first time, FWIW), as with these accounts that scrap content off solid sources to gain notoriety through minimal work.

In fact, the tweet doesn't even provide a source (it does in the "correction" under it, instead of correcting/reposting the offending claim), like the vast majority of their feed, and uses a misleading picture of microbes to go with it, arrow to the moon's plumes and all. They weren't far from just claiming life on Enceladus - in fact they go awfully close in other recent tweet ("Enceladus now has a habitable ocean" ffs...) I just have a profound distaste for these parasites drowning out the Internet nowadays, for profit then. Have you tried googling for a source lately? It's either hacker-level mastery of the search algorithms, or pages upon pages of second-hand reports, usually inaccurate and identically plain.
I don’t normally use Twitter for stuff like that. So I’ll hold my hands up and say that it was poor judgement on my behalf in this case.
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/15/2023 03:14 pm
To be fair, there's a bit of those judgement leaps also in the "serious" articles themselves. They assume that the sampled particulates from the plumes are coming from the subsurface ocean directly, which is not a given:

https://www.sciencenews.org/article/enceladus-plumes-water-ocean-saturn

And indeed, while it is likely Enceladus harbors a subsurface ocean according to the latest gravity analyses, it is not completely conclusive evidence.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/15/2023 04:36 pm
To be fair, there's a bit of those judgement leaps also in the "serious" articles themselves. They assume that the sampled particulates from the plumes are coming from the subsurface ocean directly, which is not a given:

https://www.sciencenews.org/article/enceladus-plumes-water-ocean-saturn

And indeed, while it is likely Enceladus harbors a subsurface ocean according to the latest gravity analyses, it is not completely conclusive evidence.
Also isn’t the young age of Enceladus against it having life. I’m sure I read it’s only believed to be 100 million years old, because Saturn’s moons go through cycles of destruction and construction. Hence the origin of the rings.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/15/2023 04:37 pm
Quote
A rare type of white dwarf pulsar has been discovered for the second time only, in research led by the University of Warwick. White dwarf pulsars include a rapidly spinning, burnt-out stellar remnant called a white dwarf, which lashes its neighbor—a red dwarf—with powerful beams of electrical particles and radiation, causing the entire system to brighten and fade dramatically over regular intervals. This is owing to strong magnetic fields, but scientists are unsure what causes them.

https://phys.org/news/2023-06-discovery-white-dwarf-pulsar-star.html

Related paper:

https://www.nature.com/articles/s41550-023-01995-x
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/16/2023 06:14 am
Quote
However, it appears that the length of a day on Earth hasn’t got slightly longer over deep time. There appears to have been a stalling, which may be responsible for a flourishing of plant life—and a surge in oxygen levels.

https://www.forbes.com/sites/jamiecartereurope/2023/06/15/a-day-on-earth-stalled-at-19-hours-for-a-billion-years-say-scientists/?sh=55f45f7a678c

Related paper:

Mid-Proterozoic day length stalled by tidal resonance

Abstract
We present statistical analysis of a compilation of observational constraints on the Precambrian length of day and find that the day length stalled at about 19 h for about 1 billion years during the mid-Proterozoic. We suggest that the accelerative torque of atmospheric thermal tides from solar energy balanced the decelerative torque of lunar oceanic tides, temporarily stabilizing Earth’s rotation. This stalling coincides with a period of relatively limited biological evolution known as the boring billion.

https://www.nature.com/articles/s41561-023-01202-6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/16/2023 08:41 pm
Quote
On 9 October 2022 a flash of high-intensity gamma rays was detected by NASA's Swift satellite coming from a galaxy 1.9 billion light-years away. Dubbed the "BOAT"—the "brightest of all time"—GRB 221009A was so exceptionally powerful that it actually sent shockwaves through Earth's ionosphere, the outer layer of our planet's atmosphere.

"If it had happened much closer, it would have been really bad," says Brendan O'Connor, an astronomer from George Washington University.

https://phys.org/news/2023-06-brightest-gamma-ray-ordinary-supernova.html

Two related papers:

https://www.science.org/doi/10.1126/sciadv.adi1405

https://www.science.org/doi/10.1126/sciadv.adi1405
Title: Re: Astronomy & Planetary Science Thread
Post by: Torbjorn Larsson, OM on 06/21/2023 07:50 pm
To be fair, there's a bit of those judgement leaps also in the "serious" articles themselves. They assume that the sampled particulates from the plumes are coming from the subsurface ocean directly, which is not a given:

https://www.sciencenews.org/article/enceladus-plumes-water-ocean-saturn

And indeed, while it is likely Enceladus harbors a subsurface ocean according to the latest gravity analyses, it is not completely conclusive evidence.
Also isn’t the young age of Enceladus against it having life. I’m sure I read it’s only believed to be 100 million years old, because Saturn’s moons go through cycles of destruction and construction. Hence the origin of the rings.

Nothing is given, but given [sic!] the plume serpentinization organics observed by serious science, an ocean is the most likely process producing the plumes. As for the time estimates, see more below.

Notably, the Cassini Cosmic Dust Analyzer is now reported to have found phosphates! https://www.nasaspaceflight.com/2023/06/enceladus-phosphorus/ (https://www.nasaspaceflight.com/2023/06/enceladus-phosphorus/)

There are at least two reasons this is huge.

First, it makes Enceladus the prime site for astrobiology research.

Second, it turns the usual biochemistry ideas of protocell evolution on its head. The minor biochemist part of astrobiology research has maintained that organic orthophosphates shouldn’t be around in the global ocean all other data says it evolved in. The early Earth ocean was likely dominantly acidic (precisely because of the CO2 dissolved from the atmosphere). But the early crust turnover produced local alkaline hydrothermal vent systems analogous to what we see today. Closer to mantle upwelling (today in the ocean: MORBs) the hydrothermal vents are acidic while they leach out hydrogen and iron, but when the crust modifies towards less iron compounds further away along a crustal dynamic ocean floor the vents are alkaline. This chaotic environment is what life seemingly rapidly (as going by phylogenetic tree dating, with the lower end well within the Enceladus dating lower end estimates) evolved in and which has a close analog here.

On the first, Carolyn Porko notes:

"The finding makes Enceladus “the most promising place, the lowest-hanging fruit, in our solar system to search for extraterrestrial life,” Carolyn Porco, a planetary scientist who was not involved in the research, tells National Geographic’s Charles Q. Choi.” [Smithsonian Magazine]

On the second, the team notes:

"Still, the team was not sure how Enceladus had gotten such high amounts of phosphates in the first place. So, they performed some lab experiments that suggested the moon’s ocean hosts lots of dissolved carbonates, just like soda. In this way, the so-called soda ocean can dissolve phosphate-filled rocks, leading to the high concentrations of phosphates in the water, per the New York Times’ Katrina Miller. “No one would be surprised if there’s phosphate in the rock of Enceladus. There’s phosphates on comets … it is not a big deal,” Postberg tells Space.com. “The big deal is that it is dissolved in the ocean, and with that, [it’s] readily available for the potential formation of life.”” [Smithsonian Magazine]

I expected to see some discussion about the great find, maybe I missed that, but to balance the cautious comments here let me expand more on why Enceladus ocean is of importance. The ancestral cellular metabolism that split biology off from geology by way of half alive open cells contains the carbon and energy sequestering Woods-Ljungdahl pathway, with a metabolic core known to be effectively energy producing [https://www.science.org/content/article/our-earliest-half-alive-ancestor-needed-little-boost-heat (https://www.science.org/content/article/our-earliest-half-alive-ancestor-needed-little-boost-heat)]. Recently system biology papers have first shown that nucleobase cofactors are the key molecules for producing a proliferating metabolic core. And second - just a few weeks ago - the IMO clincher result tested this in that it showed that such nucleobase cofactors needed to be either generalist or if involved in carbon fixation specialist in order to multiply the cell contents sufficiently for cell division. This tightly constrained result is precisely what is still observed in our cells!

With the possible, and now likely, phylogenetic pathway from the geology/biology split and cellular life uncovered and though arguable, reasonably tested, Enceladus looks so far like an early geology and biology laboratory that we may learn a great deal from.
Title: Re: Astronomy & Planetary Science Thread
Post by: Phil Stooke on 06/21/2023 08:53 pm
"Also isn’t the young age of Enceladus against it having life. I’m sure I read it’s only believed to be 100 million years old, because Saturn’s moons go through cycles of destruction and construction. Hence the origin of the rings."

The rings go through those cycles.  Enceladus does not.  A giant impact could destroy it and create a vast new ring, and such an impact on a pre-existing satellite presumably created the rings we see now.  But Enceladus has a substantial chunk of heavily cratered terrain which must be fairly old.  Not necessarily solar system old but I expect it has to be over a billion years since any global resurfacing.
Title: Re: Astronomy & Planetary Science Thread
Post by: eeergo on 06/22/2023 05:50 am
Thanks for the context Torbjorn, most interesting!

Another point of note I wasn't initially aware of by reading the cheerful headlines is the caveat that the data processing that brought out the presence of phosphates was not near Enceladus itself, but at the E ring! Now of course that ring is understood to be mostly composed of material coming off Enceladus and its plumes, but it's yet another logical step in the assumptions to correlate it with habitability:

- Phosphates are seen in some of Cassini's data in the E ring, which has been seen to be fed from Enceladus and its plumes.
- The rate of feed is substantial and constant over recent time.
- The observed phosphates are coming from Enceladus entirely (interesting that they've also been observed in comets!).
- The observed phosphates are unstable enough that they can't be relics accumulated from long ago.
- The observed phosphates come from Enceladus' plumes rather than some other source (i.e. spallation of ice from impacts)
- The plumes are fed by a subsurface ocean.

All this needs to be true, and individually all the propositions appear not to be too daring based on available evidence. But I can't judge how likely the ensemble actually is.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2023 06:10 am
"Also isn’t the young age of Enceladus against it having life. I’m sure I read it’s only believed to be 100 million years old, because Saturn’s moons go through cycles of destruction and construction. Hence the origin of the rings."

The rings go through those cycles.  Enceladus does not.  A giant impact could destroy it and create a vast new ring, and such an impact on a pre-existing satellite presumably created the rings we see now.  But Enceladus has a substantial chunk of heavily cratered terrain which must be fairly old.  Not necessarily solar system old but I expect it has to be over a billion years since any global resurfacing.
Looking into it further seems you right as the common age given for it is in the billions of years not millions.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2023 06:21 am
Quote
Using the Hubble Space Telescope (HST) and Jansky Very Large Array (VLA), astronomers have investigated an ultra-diffuse galaxy known as UGC 9050-Dw1. Results of the study, published June 9 on the pre-print server arXiv, yield important insights into the properties of this galaxy.

https://phys.org/news/2023-06-astronomers-explore-properties-ultra-diffuse-galaxy.html

Related paper:

https://arxiv.org/abs/2306.06164
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/22/2023 04:37 pm
Quote
An international team of astronomers reports the discovery of a new mini-Neptune exoplanet orbiting a nearby star. The newfound alien world, designated TOI-2018 b, is about two times larger and nine times more massive than the Earth. The finding was detailed in a paper published June 13 on the pre-print server arXiv.

Quote
According to the paper, TOI-2018 b has a radius of about 2.27 Earth radii and a mass of about 9.2 Earth masses, which suggests an Earth-like core with a hydrogen/helium envelope, or an ice-rock mixture. The planet orbits its host star every 7.44 days and its equilibrium temperature is estimated to be 652 K.

Quote
Dai's team has also detected another object around TOI-2018, that may be an exoplanet. It is about 50% larger than the Earth and its mass is estimated to be not larger than 3.6 Earth masses. Follow-up observations are required in order to confirm planetary status of this object.

https://phys.org/news/2023-06-astronomers-mini-neptune-exoplanet.html

Related paper:

https://arxiv.org/abs/2306.08179
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/23/2023 04:33 pm
Quote
Astronomers using W. M. Keck Observatory on Maunakea, Hawaii Island have discovered one of the lowest-mass planets whose images have been directly captured. Not only were they able to measure its mass, but they were also able to determine that its orbit is similar to the giant planets in our own solar system.

The planet, called AF Lep b, is among the first ever discovered using a technique called astrometry; this method measures the subtle movements of a host star over many years to help astronomers determine whether hard-to-see orbiting companions, including planets, are gravitationally tugging at it.

Quote
"Imaging planets is challenging," Franson said. "We only have about 15 examples, and we think this new 'dynamically informed' approach made possible by the Keck II telescope and NIRC2 adaptive optics imaging will be much more efficient compared to blind surveys which have been carried out for the past two decades."

Quote
Bowler said the team plans to continue studying AF Lep b.

"This will be an excellent target to further characterize with the James Webb Space Telescope and the next generation of large ground-based telescopes like the Giant Magellan Telescope and the Thirty Meter Telescope," Bowler said. "We're already planning more sensitive follow-up efforts at longer wavelengths to study the physical properties and atmospheric chemistry of this planet."

https://phys.org/news/2023-06-era-exoplanet-discovery-images-jupiter.html

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/acd6f6
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 06/26/2023 07:10 pm
What will NANOGrav announce Thursday?

https://youtube.com/shorts/5R0GyhJ1XUo?feature=share

https://www.sciencealert.com/a-big-gravitational-wave-announcement-is-coming-thursday-heres-why-were-excited
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/27/2023 04:24 pm
Don’t see how this theory can account for the FRBs that repeat.

https://phys.org/news/2023-06-theory-fast-radio.html

Here’s the paper:

https://arxiv.org/abs/2207.14435
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/28/2023 04:30 pm
Quote
Scientists baffled by a mysterious planet that should have been destroyed believe they have discovered why it survived.

The planet - 8 Ursae Minoris b - was identified in 2015 in the Milky Way.

But we should never have been able to see it because it should have been engulfed by a nearby dying star.

Researchers now believe 8 Ursae Minoris b escaped that fate because the dying star once had a companion that stopped its growth.

https://www.bbc.co.uk/news/science-environment-66042269.amp

Related paper:

https://www.nature.com/articles/s41586-023-06029-0
Title: Re: Astronomy & Planetary Science Thread
Post by: FutureSpaceTourist on 06/29/2023 04:50 am
https://twitter.com/chrislintott/status/1674207116263931915

Quote
Results just released from @NANOGrav and international partners show - for the first time - the signature of long-wavelength gravitational waves rippling through space. (1/n)

Quote
These waves, which buffet the Earth, are believed to most likely be the result of the mergers of supermassive black holes at the centres of galaxies (2/n)

Quote
We've detected gravitational waves before, from @LIGO and friends, but those are at much shorter wavelengths, the results of the collision of black holes a few times the mass of the Sun. What @NANOGrav and friends have found - if real - is on a much larger scale (3/n)

Quote
So large, in fact, that they have to use half the galaxy as a detector. They monitor pulses from roughly 70 pulsars, using them as precise clocks and looking for delays in the arrivals of the pulse due to the passage of a gravitational wave (4/n)

Quote
This is a staggeringly difficult measurement - requiring, amongst much else, knowing the position of the centre of mass of the solar system to a precision of less than 100m. Previous results were confused because we didn't know where Jupiter was accurately enough (5/n)

Quote
Today's results come from 15 years worth of observations, and a huge amount of efforts. The headline statistical test shows a 1 in a thousand chance that the observed pattern of delays is a coincidence (6/n)

Quote
This makes the result slightly controversial - in the parlance of stats, it's a 4-sigma detection. There's a convention in particle physics that 5-sigma is required for a 'discovery'. I'm told there is some controversy within the team as to what should be claimed (7/n)

Quote
Those on a call with press on Tuesday seemed happy enough that their detection - which has got stronger over time - is real, and they emphasised that they'd agreed in advance what level of statistical certainty would correspond to what language they would use (8/n)

Quote
I say - we're astronomers, and this looks good to me. More evidence will come soon, from international partners including @eptagw, Indian and Japanese observers @InPTA_GW, and Australians @Arc_OzGrav many of whom are also publishing data today. (9/n)

Quote
These international partners also show evidence for a similar signal, though not as strong. There is a claim, based on 3 years of data from the Chinese FAST telescope, of a stronger detection - a surprisingly rapid response from this new, powerful telescope (10/n)

Quote
So, what's causing the Earth to shake with these gravitational waves? The results are consistent with waves from supermassive black hole binaries - in orbit, but not quite merging with each other, as these behemoths whirl they lose energy by causing space itself to ripple (11/n)

Quote
Imagine two black holes, each the mass of a few million suns, locked in a 15 year orbit, slowly spiraling together, and you've got the right picture (12/n)

Quote
What's very cool is that - assuming SMBHs are responsible for the signal - there must be a population of surprisingly massive binaries out there, and they must be merging efficiently. We've learnt about the Universe already (13/n)

Quote
At least one of the papers out today presents alternative exotic theoretical explanations. I suspect this will get a lot of attention, but I don't see the need to reach for them yet. We'd expect a contribution from black hole binaries - that's likely what we've seen (14/n)

Quote
This is just the beginning. Monitoring of pulsars continues, and the team are hopeful of seeing both an expected anisotropy - a pattern in the time delays - and perhaps signals from individual sources soon (15/n)

Quote
The next stage is for the teams to share their data, and produce a combined analysis of 115 pulsars - that may give us these new results. But in the meantime, we can celebrate having just learnt a new way to look at the Universe (16/16)

Quote
I'm very very pleased to say the relevant papers are in @AAS_Publishing journals and open access. Fill your boots here: https://iopscience.iop.org/collections/apjl-230623-245-Focus-on-NANOGrav-15-year

Quote
It's late here, but I'm going to mix one of these. Happy to answer questions if I can! #Askanastronomer

https://twitter.com/kayhangultekin/status/1672978909519020032

Quote
Oh, and there's a 2pm Eastern @NANOGrav announcement/panel today (Thursday). You should tune in, even if it clashes with an @uw_icecube announcement, which has nothing to do with this result and which confused us all.

Quote
Loads of info here too:

https://nanograv.org/15yr/Summary
Title: Re: Astronomy & Planetary Science Thread
Post by: FutureSpaceTourist on 06/29/2023 04:52 am
https://twitter.com/wulei2020/status/1674269081908936704

Quote
How did Chinese scientists prove the existence of #nanohertz gravitational waves, through the observations with Five-hundred-meter Aperture Spherical Telescope (FAST)?
Watch this animation video made by The Chinese Pulsar Timing Array (#CPTA) collaboration and you’ll get a clue.
Title: Re: Astronomy & Planetary Science Thread
Post by: Stan-1967 on 06/29/2023 05:19 am
https://twitter.com/wulei2020/status/1674269081908936704

Quote
How did Chinese scientists prove the existence of #nanohertz gravitational waves, through the observations with Five-hundred-meter Aperture Spherical Telescope (FAST)?
Watch this animation video made by The Chinese Pulsar Timing Array (#CPTA) collaboration and you’ll get a clue.

In addition to the very interesting gravitational waves, the hollow earth entrance at the south pole from the 32 second mark onwards was an interesting artistic decision.  Cross post this in the SETI thread?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/29/2023 06:26 am
Quote
Scientists are reporting the first evidence that our Earth and the universe around us are awash in a background of spacetime undulations called gravitational waves. The waves oscillate very slowly over years and even decades and are thought to originate primarily from pairs of supermassive black holes leisurely spiraling together before they merge.

https://www.caltech.edu/about/news/scientists-find-evidence-for-slow-rolling-sea-of-gravitational-waves
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 06/30/2023 04:35 pm
Quote
Scientists have traced the galactic origins of thousands of "ghost particles" known as neutrinos to create the first-ever portrait of the Milky Way made from matter and not light — and it's given them a brand-new way to study the universe.

Quote
By feeding more than 60,000 detected neutrino cascades collected over 10 years into a machine-learning algorithm, the physicists built up a stunning picture: an ethereal, blue-tinged image showing the neutrinos' sources all across our galaxy.

The map showed that the neutrinos were being overwhelmingly produced in regions with previously detected high gamma-ray counts, confirming past suspicions that many ghost particles are summoned as byproducts of cosmic rays smashing into interstellar gas. It also left the physicists awestruck.

https://www.livescience.com/physics-mathematics/particle-physics/ghost-particle-image-is-the-1st-view-of-our-galaxy-in-anything-other-than-light

Related paper:

https://www.science.org/doi/10.1126/science.adc9818

And related video:

https://youtu.be/GzdXXrRTFcw
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/04/2023 11:42 am
Quote
Comet C/2023 E1 ATLAS was discovered in March 2023 by the Asteroid Terrestrial-Impact Last Alert System (ATLAS), which is funded by NASA and operated by the University of Hawaii. This array of four telescopes spread out in Hawaii, Chile and South Africa scans the sky for near-Earth objects in order to warn of any potential hazards heading Earth's way.

Quote
By the time July's new moon arrives on July 17, the comet will be approaching its maximum brightness and will have moved eastward toward the constellation Cetus, the Whale. If you go looking for the comet yourself, don't expect to see a bright green snowball with a well-pronounced tail; through most backyard optics, the comet will likely appear as a hazy, greenish smudge.

https://www.space.com/comet-c2023-e1-atlas-little-dipper-how-to-see
Title: Re: Astronomy & Planetary Science Thread
Post by: jbenton on 07/05/2023 03:56 pm
So, about a fortnight ago, this just dropped:

https://www.sciencealert.com/we-just-found-one-of-the-rarest-stars-in-the-galaxy (https://www.sciencealert.com/we-just-found-one-of-the-rarest-stars-in-the-galaxy)

Apparently, astronomers have detected another white dwarf pulsar (one of only two examples ever found, thus far). They found it 773 light years away.

From the article's description of the first white dwarf pulsar:

Quote
White dwarfs are a similar kind of stellar remnant. They're the collapsed cores of dead stars below around 8 solar masses. They're less dense than neutron stars and have larger radii. As far as we knew until just a few years ago, they also don't seem to turn into pulsars.

Then, in 2016, astronomers found what they called the first white dwarf pulsar, a star named AR Scorpii. AR Scorpii is a little bit different from a traditional pulsar. It's a white dwarf in a binary system with a red dwarf star. As it spins, its beams sweep past the red dwarf, causing it to brighten across multiple wavelengths on regular, 1.97-minute time frames; the pulsations we see are not from the white dwarf's beams directly but from the effect those beams have on the red dwarf companion.

The article continues to explain how different that white dwarf is from most others we've found. Here is just a portion of the articles description of the second discovery:

Quote
But a sample size of one star makes it impossible to confirm, so Pelisoli and her colleagues searched for more. They combed survey data looking for stars with similar characteristics to AR Scorpii. Then, they followed up with their candidates to see if they matched.

"After observing a couple dozen candidates, we found one that showed very similar light variations to AR Scorpii. Our follow-up campaign with other telescopes revealed that every five minutes or so, this system sent a radio and X-ray signal in our direction," she says.

...

A second study led by astrophysicist Alex Schwope of Leibniz Institute for Astrophysics Potsdam in Germany independently found J1912-4410 in data from the X-ray space observatory eROSITA. They, too, concluded that the object is a white dwarf pulsar like AR Scorpii, suggesting strongly that there are more of these objects out there.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/10/2023 10:48 am
Apparently Betelgeuse maybe much closer to its death than previously estimated. That it may have less than 300 years of fuel left to burn through at its core. It’s based on the idea that it’s actually bigger than most observations make it to be and that it has already started burning Carbon at its core.

https://www.space.com/betelgeuse-supernova-in-our-lifetime-study-unsure

Here’s the paper itself.

https://arxiv.org/pdf/2306.00287.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/10/2023 10:51 am
An Ancient Greek Astronomical Calculation Machine Reveals New Secrets

https://www.scientificamerican.com/article/an-ancient-greek-astronomical-calculation-machine-reveals-new-secrets/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/10/2023 11:07 pm
Quote
Researchers said on Monday they have spotted a truly extreme planet beyond our solar system, a blazingly hot world a bit bigger than Neptune that orbits a sun-like star every 19 hours and appears to be wrapped in metallic clouds made of titanium and silicates that reflect most incoming light back into space.

https://www.reuters.com/technology/space/alien-planet-with-metallic-clouds-resembles-a-giant-mirror-space-2023-07-10/

Related paper:

https://www.aanda.org/articles/aa/full_html/2023/07/aa46117-23/aa46117-23.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/11/2023 08:13 am
Quote
There are likely many more exoplanets with liquid water than previously thought, according to a new science paper published today. That massively increases the chances of life existing elsewhere in the galaxy, say the authors.

“It was estimated that around one rocky planet around every 100 stars would have liquid water,” said lead researcher Dr Lujendra Ojha from Rutgers University, New Jersey, today at the Goldschmidt geochemistry conference in Lyon, France. “The new model shows that if the conditions are right, this could approach one planet per stars—so we are a hundred times more likely to find liquid water than we thought.”

https://www.forbes.com/sites/jamiecartereurope/2023/07/10/earth-like-planets-are-100-times-more-common-than-we-thought-say-scientists/?sh=74418d9c54d2

Related paper:

https://www.nature.com/articles/s41467-022-35187-4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/11/2023 07:15 pm
The fifty percent mark has been reached on the construction of the ELT:

https://youtu.be/oC2nWe1wbFk
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/13/2023 04:10 pm
Test for Cosmological Parity Violation Using the 3D Distribution of Galaxies

ABSTRACT

We show how the galaxy four-point correlation function can test for cosmological parity violation. The detection of cosmological parity violation would reflect previously unknown forces present at the earliest moments of the Universe. Recent developments both in rapidly evaluating galaxy N-point correlation functions and in determining the corresponding covariance matrices make the search for parity violation in the four-point correlation function possible in current and upcoming surveys such as those undertaken by Dark Energy Spectroscopic Instrument, the Euclid satellite, and the Vera C. Rubin Observatory. We estimate the limits on cosmic parity violation that could be set with these data.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.201002
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/14/2023 10:03 am
Quote
A trio of astrophysicists, two from Colgate University and the third from the University of Texas, has found possible evidence of dark stars, courtesy of data from the James Webb Space Telescope. In their paper published in Proceedings of the National Academy of Sciences, Cosmin Ilie, Jillian Pauline and Katherine Freese, describe their study of data surrounding three galaxies spotted by the JWST and how they might relate to dark stars.

https://phys.org/news/2023-07-james-webb-space-telescope-evidence.html

Related paper:

https://www.pnas.org/doi/10.1073/pnas.2305762120
Title: Re: Astronomy & Planetary Science Thread
Post by: deltaV on 07/15/2023 01:35 am
Ars (reprinting from The Conversation) had an article yesterday about using diffractive lenses in space telescopes  (https://arstechnica.com/space/2023/07/a-new-thin-lensed-telescope-design-could-far-surpass-james-webb/). (The author isn't independent so maybe it should be called an opinion piece rather than a news article.)
Title: Re: Astronomy & Planetary Science Thread
Post by: VSECOTSPE on 07/15/2023 04:47 am

Diffractive or Fresnel lenses — essentially flat membranes that bend light moving through them via many small prisms instead of big curved lenses or reflective surfaces — for space-based observation have been pursued before.  Here’s a couple examples:

MOIRE:

https://www.darpa.mil/program/membrane-optic-imager-real-time-exploitation

https://www.darpa.mil/news-events/2013-12-05

https://www.ball.com/aerospace/programs/earth-science-weather/moire

https://m.youtube.com/watch?v=q5oqle9Ct4Q

https://www.prnewswire.com/news-releases/ball-aerospace-completes-final-phase-of-darpa-moire-telescope-program-260042881.html

FalconSat-7:

https://www.spacesymposium.org/wp-content/uploads/2017/10/B.Smith_31st_Space_Symposium_Tech_Track_paper.pdf

https://ntrs.nasa.gov/api/citations/20190026685/downloads/20190026685.pdf

https://www.eoportal.org/satellite-missions/falconsat-7

IIRC, diffractive lenses trade spectral range for resolution, so if you don’t need a lot of spectrum and it’s resolution at low weight that you need, they’re potentially a good option.  But someone needs to do a smaller mission or two with Fresnel lenses before anyone gets serious about a great observatory-class mission with them.

(They’re also an option for concentrating sunlight on solar arrays, but there are mass tradeoffs.)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/16/2023 06:33 am
Quote
A supernova that erupted when a massive star died could have destroyed our infant solar system — if it weren't protected by a cocoon of molecular gas.

https://www.livescience.com/space/astronomy/a-nearby-supernova-nearly-blew-our-solar-system-to-bits-4-billion-years-ago-new-research-suggests
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/18/2023 08:10 am
Quote
Astronomers have found evidence that some stars boast unexpectedly strong surface magnetic fields, a discovery that challenges current models of how they evolve.

https://phys.org/news/2023-07-astronomers-evidence-unusual-stellar-evolution.html

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/acd780
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/18/2023 04:23 pm
Quote
Astronomers from the University of Science and Technology of China in Hefei report the discovery of a new faint tidal disruption event (TDE). The newfound TDE, designated AT 2023clx is the faintest and closest optical TDE so far detected. The finding was published July 10 on the preprint server arXiv.

https://phys.org/news/2023-07-tidal-disruption-event-chinese-astronomers.html

Related paper:

https://arxiv.org/abs/2307.04297
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/19/2023 04:27 pm
Quote
Most planetary systems we've found out there in the wider galaxy also seem to follow this trend. According to theory, though, two planets could share the same orbit – and now, for the first time, astronomers think we might have evidence of this in a baby planetary system some 370 light-years from Earth.

https://www.sciencealert.com/we-just-got-the-first-evidence-of-two-planets-sharing-the-same-orbit

Related video:

https://youtu.be/T7-cp8Om_qU
Title: Re: Astronomy & Planetary Science Thread
Post by: rsdavis9 on 07/19/2023 04:56 pm
Quote
Most planetary systems we've found out there in the wider galaxy also seem to follow this trend. According to theory, though, two planets could share the same orbit – and now, for the first time, astronomers think we might have evidence of this in a baby planetary system some 370 light-years from Earth.

https://www.sciencealert.com/we-just-got-the-first-evidence-of-two-planets-sharing-the-same-orbit

Related video:

https://youtu.be/T7-cp8Om_qU

So this appears to occupy l3 or l4?
Question: Can equal size planets be in each others l3 and l4 points and have stable orbits?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/19/2023 06:27 pm
Two-faced star exposed in first for astronomy

Quote
An unusual white dwarf star is made of hydrogen on one side and helium on the other. 

In a first for white dwarfs, the burnt-our cores of dead stars, astronomers from institutions including the California Institute of Technology (Caltech) and the University of Warwick have discovered that at least one member of this cosmic family is two faced. The findings, that one side of the white dwarf is composed of hydrogen, while the other is made up of helium, were published today in Nature.

https://warwick.ac.uk/newsandevents/pressreleases/?newsItem=8a17841b8949662201896ec1d6684a90
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/19/2023 06:28 pm
Quote
Most planetary systems we've found out there in the wider galaxy also seem to follow this trend. According to theory, though, two planets could share the same orbit – and now, for the first time, astronomers think we might have evidence of this in a baby planetary system some 370 light-years from Earth.

https://www.sciencealert.com/we-just-got-the-first-evidence-of-two-planets-sharing-the-same-orbit

Related video:

https://youtu.be/T7-cp8Om_qU

So this appears to occupy l3 or l4?
Question: Can equal size planets be in each others l3 and l4 points and have stable orbits?
Also how stable can this arrangement be over the longer evolution of the system?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/20/2023 11:44 am
They don’t have any real clue what this, for a start physics won’t allow it to be a pulsar as it’s too slow and it’s highly unlikely to be a Magnetar or a White Dwarf either.

Quote
On Wednesday, researchers announced the discovery of a new astronomical enigma. The new object, GPM J1839–10, behaves a bit like a pulsar, sending out regular bursts of radio energy. But the physics that drives pulsars means that they'd stop emitting if they slowed down too much, and almost every pulsar we know of blinks at least once per minute.

GPM J1839–10 takes 22 minutes between pulses. We have no idea what kind of physics or what kind of objects can power that.

https://arstechnica.com/science/2023/07/new-slow-repeating-radio-source-we-have-no-idea-what-it-is/

Related paper:

https://www.nature.com/articles/s41586-023-06202-5
Title: Re: Astronomy & Planetary Science Thread
Post by: Zed_Noir on 07/20/2023 12:13 pm
They don’t have any real clue what this, for a start physics won’t allow it to be a pulsar as it’s too slow and it’s highly unlikely to be a Magnetar or a White Dwarf either.

Quote
On Wednesday, researchers announced the discovery of a new astronomical enigma. The new object, GPM J1839–10, behaves a bit like a pulsar, sending out regular bursts of radio energy. But the physics that drives pulsars means that they'd stop emitting if they slowed down too much, and almost every pulsar we know of blinks at least once per minute.

GPM J1839–10 takes 22 minutes between pulses. We have no idea what kind of physics or what kind of objects can power that.

https://arstechnica.com/science/2023/07/new-slow-repeating-radio-source-we-have-no-idea-what-it-is/

Related paper:

https://www.nature.com/articles/s41586-023-06202-5
It's an alien artifact :P
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/20/2023 05:04 pm
They don’t have any real clue what this, for a start physics won’t allow it to be a pulsar as it’s too slow and it’s highly unlikely to be a Magnetar or a White Dwarf either.

Quote
On Wednesday, researchers announced the discovery of a new astronomical enigma. The new object, GPM J1839–10, behaves a bit like a pulsar, sending out regular bursts of radio energy. But the physics that drives pulsars means that they'd stop emitting if they slowed down too much, and almost every pulsar we know of blinks at least once per minute.

GPM J1839–10 takes 22 minutes between pulses. We have no idea what kind of physics or what kind of objects can power that.

https://arstechnica.com/science/2023/07/new-slow-repeating-radio-source-we-have-no-idea-what-it-is/

Related paper:

https://www.nature.com/articles/s41586-023-06202-5
It's an alien artifact :P
You are that meme and I claim my ten pounds!!!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/25/2023 07:43 pm
Zooming in on V960 Mon:

https://youtu.be/YKOHFRAvSXk
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/26/2023 11:56 am
Quote
But until recently it was assumed that 55 Cancri e would be rotationally, tidally locked with its parent star, so that one side of the planet would remain in perpetual daylight.

Quote
New observations reveal that in fact 55 Cancri e may have a day and night cycle.

Using both NASA’s Webb Space Telescope observations as well as observations using ESA’s (European Space Agency) Characterizing Exoplanet Satellite (CHEOPS), Stockholm University astronomer Alexis Brandeker and colleagues found that 55 Cancri e has more temperature and orbital variations than they ever expected.

Quote
But the team has seen temperature variations around the planet which could indicate that it has a normal day-night cycle. That’s a possibility, says Brandeker, because 55 Cancri e may have a slightly eccentric orbit due to long-term gravitational perturbations caused by other members of the planetary system.

https://www.forbes.com/sites/brucedorminey/2023/07/25/crazy-close-orbiting-lava-world-may-still-have-day-night-cycles-says-astronomer/?sh=132639aa7b3e

Related video interview:

https://youtu.be/CEg2qGl4WKo
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/27/2023 08:23 am
Quote
A strange dark stone found recently in a remote section of the Sahara desert could be the first ever known case of a rock launched from the Earth that returned to the planet as a meteorite thousands of years later.

The reddish-brown dark stone, found in Morocco in 2018, may have been ejected into space about 10,000 years ago following an asteroid collision with Earth, and remained in orbit before crashing back onto the planet, suspect scientists, including Jerome Gattacceca from CNRS in France.

https://www.independent.co.uk/space/meteorite-earth-launched-rock-homecoming-b2382023.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 07/30/2023 10:30 am
Seems Avi Loeb is making himself unpopular with his scientific peers through his wild claims. In fact they are now boycotting peer reviewing his work.

https://www.newser.com/story/338108/harvard-astrophysicists-alien-obsession-rankles-colleagues.html
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/04/2023 06:02 am
Quote
The most recent batch of processed photos from NASA’s James Webb Space Telescope features the Messier 57 nebula in never-before-seen clarity, informing astronomers of our sun’s future with new depth and charm.

https://www.forbes.com/sites/hanwenzhang/2023/08/03/what-to-know-about-the-messier-57-nebula-the-webb-telescopes-baffling-and-brilliant-new-photo-subject/?sh=6f1356707b9c
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/07/2023 04:27 pm
Sun erupts with long-duration X1.6-class Solar flare:

https://youtu.be/Ki379Od1Mn4
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/07/2023 06:17 pm
Quote
High-frequency magnetic waves surging through the sun may explain why the temperature of our star's atmosphere is 200 times hotter than its surface.

https://www.livescience.com/space/the-sun/mysterious-waves-of-magnetism-may-explain-why-the-suns-atmosphere-is-hotter-than-physicists-thought-possible

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/acd780
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/10/2023 04:15 pm
Watch an alien world orbit around its star in 17 year time-lapse:

https://youtu.be/VRNohj9LJug
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/11/2023 08:49 pm
Score one for MOND here it seems over dark matter.

Quote
A new study reports conclusive evidence for the breakdown of standard gravity in the low acceleration limit from a verifiable analysis of the orbital motions of long-period, widely separated, binary stars, usually referred to as wide binaries in astronomy and astrophysics.

Quote
On the results, Chae says, "It seems impossible that a conspiracy or unknown systematic can cause these acceleration-dependent breakdown of the standard gravity in agreement with AQUAL. I have examined all possible systematics as described in the rather long paper. The results are genuine. I foresee that the results will be confirmed and refined with better and larger data in the future. I have also released all my codes for the sake of transparency and to serve any interested researchers."

Quote
A new revolution in physics seems now under way. Milgrom says, "Chae's finding is a result of a very involved analysis of cutting-edge data, which, as far as I can judge, he has performed very meticulously and carefully. But for such a far-reaching finding—and it is indeed very far reaching—we require confirmation by independent analyses, preferably with better future data."

"If this anomaly is confirmed as a breakdown of Newtonian dynamics, and especially if it indeed agrees with the most straightforward predictions of MOND, it will have enormous implications for astrophysics, cosmology, and for fundamental physics at large."

https://phys.org/news/2023-08-smoking-gun-evidence-gravity-gaia-wide.amp

Here’s the related paper:

https://iopscience.iop.org/article/10.3847/1538-4357/ace101
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 08/11/2023 11:10 pm
Score one for MOND here it seems over dark matter.

MOND is one of the possible explanations for dark matter; not a refutation. The term 'dark matter' should not be taken literally; it's a placeholder term signifying that there appears to be more gravity in the universe than can be accounted for by general relativity and known sources of gravitation. An unknown form of matter is one explanation; MOND is another.

The results of analysing wide binaries are interesting. But seeming inconsistencies with general relativity have a habit of disappearance after closer scrutiny (which these results will now be subject to).

But here's hoping. I'm sure physicists will be delirious with excitement if general relativity is shown to have a crack in it!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/12/2023 08:19 am
Score one for MOND here it seems over dark matter.

MOND is one of the possible explanations for dark matter; not a refutation. The term 'dark matter' should not be taken literally; it's a placeholder term signifying that there appears to be more gravity in the universe than can be accounted for by general relativity and known sources of gravitation. An unknown form of matter is one explanation; MOND is another.

The results of analysing wide binaries are interesting. But seeming inconsistencies with general relativity have a habit of disappearance after closer scrutiny (which these results will now be subject to).

But here's hoping. I'm sure physicists will be delirious with excitement if general relativity is shown to have a crack in it!
That’s a fair point. But surely you have to concede that Dark Matter as a subject is often framed in terms of looking for a Dark Matter particle.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 08/13/2023 11:49 am
Quote
In recent research published by myself and my colleague Tony Yeates in the journal Tectonophysics, we investigate what we believe – based on many years of experience in asteroid impact research – is the world’s largest known impact structure, buried deep in the earth in southern New South Wales.

The Deniliquin structure, yet to be further tested by drilling, spans up to 520 kilometres in diameter. This exceeds the size of the near-300km-wide Vredefort impact structure in South Africa, which to date has been considered the world’s largest.

Quote
The impact that caused it may have occurred during what’s known as the Late Ordovician mass extinction event. Specifically, I think it may have triggered what’s called the Hirnantian glaciation stage, which lasted between 445.2 and 443.8 million years ago, and is also defined as the Ordovician-Silurian extinction event.

This huge glaciation and mass extinction event eliminated about 85% of the planet’s species. It was more than double the scale of the Chicxulub impact that killed off the dinosaurs.

It is also possible the Deniliquin structure is older than the Hirnantian event, and may be of an early Cambrian origin (about 514 million years ago).

https://theconversation.com/new-evidence-suggests-the-worlds-largest-known-asteroid-impact-structure-is-buried-deep-in-southeast-australia-209593

Related paper:

https://www.sciencedirect.com/science/article/abs/pii/S0040195122002487
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/14/2023 10:34 am
Quote
Black holes have a preference for forming around two "universal" masses equivalent to about nine and 16 times the mass of our sun, according to a new study of the frequency of the gravitational-wave ‘chirps’ released when two black holes collide and merge. These findings could ultimately pave the way for an independent measure of the expansion of the Universe.

https://www.space.com/gravitational-waves-show-black-hole-collision-mass
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 08/14/2023 11:45 pm
But surely you have to concede that Dark Matter as a subject is often framed in terms of looking for a Dark Matter particle.

Sure. But, that's not too surprising as a novel particle is one of the two major possible explanations for dark matter.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/15/2023 04:34 pm
Sounds like somewhere the Silver Surfer might hang out.

Quote
A massive stellar behemoth is experiencing violent waves three times as tall as our sun crashing down on its surface. Known as a "heartbeat star," the extreme object also periodically pulses in brightness as the gravity of a close companion stretches it into an oblate shape.

Quote
The waves are absolutely huge, rising about 4 million kilometers (2.5 million miles) above the primary star's surface. They form when the companion star reaches what's known as periastron, which is the closest point in its 32.8-day orbit around the primary star. That primary star is also huge, with a gargantuan radius of  16.7 million kilometers (10.4 million miles) or 24 times the radius of our sun. The outer layers of this bloated star are diffuse and more weakly held by gravity, making it easier for the gravitational tides to distort them.

https://www.space.com/supersonic-tsunamis-three-times-tall-sun-heartbreak-star

Related paper:

https://www.nature.com/articles/s41550-023-02036-3.epdf?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/17/2023 04:42 pm
Quote
Astronomers using the James Webb Space Telescope (JWST) have confirmed that a distant smudge of light named for a lucky birthday girl on Earth is one of the earliest known galaxies in the universe.

https://www.livescience.com/space/cosmology/13-billion-year-old-maisies-galaxy-is-one-of-the-oldest-objects-in-the-universe-james-webb-telescope-reveals

Related paper:

https://www.nature.com/articles/s41586-023-06521-7.epdf?

And related video:

https://youtu.be/M1n82zTBwQY
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/17/2023 10:00 pm
New type of star gives clues to magnetars origins (ESOcast 264 Light)

https://youtu.be/W9CRZhN6Vxw
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/18/2023 04:36 pm
Quote
A newly discovered star system is breaking records — and helping scientists unravel the mysteries of an extreme type of planet known as hot Jupiters. In a paper published Aug. 14 in the journal Nature Astronomy, researchers describe how the system could help further our understanding of worlds beyond our solar system.

Quote
The binary system, located 1,400 light-years away, consists of a "white dwarf" and a "brown dwarf."

Quote
This particular brown dwarf is unusual in that it is about the same size as Jupiter but has about 80 times Jupiter's mass. In other words, it's incredibly dense — and incredibly hot. The object is tidally locked, with one side permanently facing its companion star while the other side faces away. On the "day side," temperatures soar to more than 17,000 degrees Fahrenheit (9,500 degrees Celsius) — about 7,000 F (3,900 C) hotter than the surface of the sun. Its "night side" is cooler — about 4,900 F (2,700 C).

https://www.livescience.com/space/exoplanets/bizarre-failed-star-the-size-of-jupiter-is-2000-degrees-hotter-than-the-sun

Related paper:

https://www.nature.com/articles/s41550-023-02048-z?
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/21/2023 08:00 am
Podcast covering the latest research into the Antikythera Mechanism as a celestial calculator. I got caught by spoilers for the new Indiana Jones film, which I haven’t seen yet, so beware that.

https://shows.acast.com/dansnowshistoryhit/episodes/the-ancient-greek-computer-the-antikythera-mechanism
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/22/2023 11:52 am
Quote
Now, we have a new comet that could reach naked eye visibility over the next few weeks: C/2023 P1 Nishimura. The comet was discovered by Hideo Nishimura while shooting wide-field images from Kakegawa, Japan on the night of August 11th. At the time, the comet displayed respectable a 5’ coma. Score one for the human observers, versus robotic all-sky surveys…

https://www.universetoday.com/162802/comet-p1-nishimura-could-be-bright-over-the-next-few-weeks/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/23/2023 09:04 am
Quote
Researchers have identified a new speed limit for the universe’s most extreme collisions. According to a study published in the journal Physical Review Letters, the "maximum possible recoil velocity" for colliding black holes exceeds a whopping 63 million mph (102 million km/h) — about one-tenth the speed of light. This peak occurs when the collision conditions are at the tipping point between the two black holes either merging together or scattering apart as they approach each other, according to the study authors.

https://www.livescience.com/physics-mathematics/newly-discovered-black-hole-speed-limit-hints-at-new-laws-of-physics

Related paper:

https://storage.pardot.com/640833/1691616553j1lZZmjZ/LZ17765_min.pdf
Title: Astronomy & Planetary Science Thread
Post by: Star One on 08/24/2023 05:03 pm
Cool Worlds - Why Exomoons Are So Important:

https://youtu.be/b2crw2DGy38?si=NS5vjzv6TikoHSHX

He argues that Exomoons may be more likely to host life than exoplanets. Also how unless you cannot say if you’ve found life unless you consider exomoons.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 08/24/2023 10:41 pm
Has JWST found supermassive Dark Matter Stars?

She sounds somewhat sceptical about this paper, though points out it would explain where Supermassive Black Holes come from. As they would be so massive these Dark Matter Stars that they would instantly collapse into Supermassive Black Holes:

https://youtu.be/hpYWK4x5rUA?si=vr1xc3-TtP1hd486
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/02/2023 11:53 am
New paper on a much smaller proposed planet nine than Mike Brown. This sounds more in line with Alan Stern’s proposals for another planet in the Kuiper Belt.

Is There an Earth-like Planet in the Distant Kuiper Belt?

Abstract
The orbits of trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system. Here we used N-body computer simulations to investigate the effects of a hypothetical Kuiper Belt planet (KBP) on the orbital structure of TNOs in the distant Kuiper Belt beyond ∼50 au. We used observations to constrain model results, including the well-characterized Outer Solar System Origins Survey (OSSOS). We determined that an Earth-like planet (m ∼ 1.5–3 M⊕) located on a distant (semimajor axis a ∼ 250–500 au, perihelion q ∼ 200 au) and inclined (i ∼ 30°) orbit can explain three fundamental properties of the distant Kuiper Belt: a prominent population of TNOs with orbits beyond Neptune's gravitational influence (i.e., detached objects with q &gt; 40 au), a significant population of high-i objects (i &gt; 45°), and the existence of some extreme objects with peculiar orbits (e.g., Sedna). Furthermore, the proposed KBP is compatible with the existence of identified gigayear-stable TNOs in the 2:1, 5:2, 3:1, 4:1, 5:1, and 6:1 Neptunian mean motion resonances. These stable populations are often neglected in other studies. We predict the existence of an Earth-like planet and several TNOs on peculiar orbits in the outer solar system, which can serve as observationally testable signatures of the putative planet's perturbations.

https://iopscience.iop.org/article/10.3847/1538-3881/aceaf0
Title: Re: Astronomy & Planetary Science Thread
Post by: yg1968 on 09/02/2023 03:15 pm
SBAG wants reconnaissance mission to Apophis before it reaches Earth:
https://spacepolicyonline.com/news/sbag-wants-reconnaissance-mission-to-apophis-before-it-reaches-earth/

https://twitter.com/SpcPlcyOnline/status/1697659372904522165
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/05/2023 11:58 am
More evidence against Dark Matter? What does the GAIA data actually show?

https://youtu.be/3o8kaCUm2V8?si=ptn-ulTdnjgBSuaP
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 09/05/2023 08:10 pm
More evidence against Dark Matter? What does the GAIA data actually show?

https://youtu.be/3o8kaCUm2V8?si=ptn-ulTdnjgBSuaP
::) ::) ::) ::)

MOND can only be a valid theory if it can correctly deal with ALL The observations and points of the theory of gravity that it replaces. If it is kinda good for this, but can't say anything about that (which normal gravity can), then its not ready for prime time.
Title: Re: Astronomy & Planetary Science Thread
Post by: Dizzy_RHESSI on 09/06/2023 02:41 pm
MOND can only be a valid theory if it can correctly deal with ALL The observations and points of the theory of gravity that it replaces. If it is kinda good for this, but can't say anything about that (which normal gravity can), then its not ready for prime time.

It's worse than that, taken at face value the wide binaries are inconsistent with MOND and Newtonian gravity. In this regime MOND should be almost indistinguishable from Newtonian gravity because of it's External Field Effect. Looking at the distributions shows the data don't match any of the naive predictions, but they do agree with what you would expect if your binary sample is contaminated.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/06/2023 04:21 pm
Quote
Astronomers report the discovery of a new massive and quiescent galaxy at a high redshift. The galaxy, which received designation COSMOS-1047519, was detected using the Keck I telescope. The finding was detailed in a paper published August 29 on the pre-print server arXiv.

https://phys.org/news/2023-09-astronomers-massive-quiescent-galaxy.html

Related paper:

https://arxiv.org/abs/2308.15011
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/06/2023 04:25 pm
The furtherest ever galactic magnetic field (ESOcast 267 light)

https://youtu.be/TYvZRhjwieo?si=rWgfv68Ero7k12y7
Title: Re: Astronomy & Planetary Science Thread
Post by: Barley on 09/06/2023 04:44 pm
MOND is a hypothesis not a theory.  Measurements of binary stars are data not theory.

Hypothesis and data can be wrong, but not simply because they are not theories.

The missing matter is also data.  Calling the missing matter "dark matter" does not make it a theory or even a hypothesis.  Although saying there is actually unobserved matter of some kind is a hypothesis.
Title: Re: Astronomy & Planetary Science Thread
Post by: Dizzy_RHESSI on 09/08/2023 10:35 am
MOND is a hypothesis not a theory.  Measurements of binary stars are data not theory.

Hypothesis and data can be wrong, but not simply because they are not theories.

What exactly do you mean by that? The criticism leveled against the result has nothing to do with what you chose to call a model.
Title: Re: Astronomy & Planetary Science Thread
Post by: Barley on 09/08/2023 04:01 pm
MOND is a hypothesis not a theory.  Measurements of binary stars are data not theory.

Hypothesis and data can be wrong, but not simply because they are not theories.

What exactly do you mean by that? The criticism leveled against the result has nothing to do with what you chose to call a model.

MOND is a hypothesis not a theory.  Measurements of binary stars are data not theory.

Hypothesis and data can be wrong, but not simply because they are not theories.

The missing matter is also data.  Calling the missing matter "dark matter" does not make it a theory or even a hypothesis.  Although saying there is actually unobserved matter of some kind is a hypothesis.
MOND is a hypothesis not a theory.  Measurements of binary stars are data not theory.

Hypothesis and data can be wrong, but not simply because they are not theories.

What exactly do you mean by that? The criticism leveled against the result has nothing to do with what you chose to call a model.


 ::) ::) ::) ::)

MOND can only be a valid theory if it can correctly deal with ALL The observations and points of the theory of gravity that it replaces. If it is kinda good for this, but can't say anything about that (which normal gravity can), then its not ready for prime time.
MOND does not have to be a theory to be important.  Data does not have to match any particular theory or hypothesis to be important.  The most important data is the stuff you can't explain.


IMHO the search for dark matter mirrors the search for the luminiferous aether.  Which was an important frontier for almost a century.  The search advanced physics, even though the exact question was never quite answered.  People are still refining some of the experiments, although they are no longer described as searches for the eather.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/09/2023 11:56 am
Quote
Recent breakthroughs at the international CLOUD project, based at the nuclear research center CERN, have revealed fascinating insights into the mysteries of cloud formation.

This natural process is of paramount importance in comprehending the planet’s shifting climate patterns, as it plays a significant role in reflecting solar radiation, consequently impacting the Earth’s temperature.

https://www.earth.com/news/mysteries-in-the-sky-how-trees-impact-cloud-formation/
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 09/09/2023 10:44 pm
IMHO the search for dark matter mirrors the search for the luminiferous aether.

No. The luminiferous aether did not exist. Dark matter exists - there are numerous observations demonstrating that - it's just that we don't know what it is.
Title: Astronomy & Planetary Science Thread
Post by: Star One on 09/10/2023 10:45 am
Avi Loeb over extrapolating from the available date again?

Quote
Avi Loeb, an astrophysicist at Harvard University in the US, has published a press release claiming that some of the 700 or so spherical metallic fragments (spherules) he recovered from the bottom of the Pacific Ocean, just off the coast of Papua New Guinea, are from beyond the Solar System.

The discovery was quite interesting because, although such spherules are distributed globally, it is not easy to recover them from the depths of the ocean bed – requiring a dredging operation with a powerful magnet. But Loeb has speculated that the spherules may be related to the passage of an interstellar meteor, IM1, which burned up over the South Pacific Ocean in January, 2014. He has even hypothesised that the spherules are actually debris from an alien spacecraft. I commented at the time that I’d need firm analytical evidence to accept such interpretations.

Quote
I have another, equally speculative, suggestion. The Marshall Islands are only a few hundred kilometres or so from the region where Loeb searched. The Islands were the site of 67 nuclear tests by the US between 1946 and 1958, causing radiation damage. The spherules could be fallout from these tests – a type of human-generated supernova.

https://theconversation.com/have-we-really-found-the-first-samples-from-beyond-the-solar-system-the-evidence-is-not-convincing-212789

Here’s Loeb’s paper:

https://arxiv.org/abs/2308.15623

And here’s Loeb’s related press release:

https://projects.iq.harvard.edu/galileo/news/spherule-analysis-finds-evidence-extrasolar-composition
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 09/11/2023 02:28 pm
Avi Loeb over extrapolating from the available date again?

Quote
Avi Loeb, an astrophysicist at Harvard University in the US, has published a press release claiming that some of the 700 or so spherical metallic fragments (spherules) he recovered from the bottom of the Pacific Ocean, just off the coast of Papua New Guinea, are from beyond the Solar System.

The discovery was quite interesting because, although such spherules are distributed globally, it is not easy to recover them from the depths of the ocean bed – requiring a dredging operation with a powerful magnet. But Loeb has speculated that the spherules may be related to the passage of an interstellar meteor, IM1, which burned up over the South Pacific Ocean in January, 2014. He has even hypothesised that the spherules are actually debris from an alien spacecraft. I commented at the time that I’d need firm analytical evidence to accept such interpretations.

Quote
I have another, equally speculative, suggestion. The Marshall Islands are only a few hundred kilometres or so from the region where Loeb searched. The Islands were the site of 67 nuclear tests by the US between 1946 and 1958, causing radiation damage. The spherules could be fallout from these tests – a type of human-generated supernova.

https://theconversation.com/have-we-really-found-the-first-samples-from-beyond-the-solar-system-the-evidence-is-not-convincing-212789

Here’s Loeb’s paper:

https://arxiv.org/abs/2308.15623

And here’s Loeb’s related press release:

https://projects.iq.harvard.edu/galileo/news/spherule-analysis-finds-evidence-extrasolar-composition
i cant even brnig myself to read what he says anymore. Saw a thing about those spheres - how they are actually found all over the ocean, and easily explained.

Abi Loeb is just adicted to the attention he gets for saying aliens. Hes lost all credibility.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/13/2023 04:38 pm
A new paper proposes that there maybe three stellar mass black holes only 150 light years away that ten times closer than previously thought for the nearest black hole.

https://www.livescience.com/space/black-holes/the-closest-black-holes-to-earth-may-be-10-times-closer-than-we-thought
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/15/2023 04:32 pm
Quote
In 1217, a German monk looked to the starry southwest sky and noticed a normally faint star shining with unusual intensity. It continued to blaze for several days. Abbott Burchard, the leader of Ursberg Abbey at the time, recorded the sight in that year's chronicle. "A wonderful sign was seen," he wrote, adding that the mysterious object in the constellation Corona Borealis "shone with great light" for "many days."

This medieval manuscript may have been the first record of a rare space phenomenon called a recurrent nova — a dead star siphoning matter from a larger companion, triggering repeated flares of light at regular intervals. According to new research, the "wonderful" star in question may be T CrB, which sits in the constellation Corona Borealis and dramatically increases in brightness for about a week every 80 years. But it has been scientifically documented only twice — once in 1866, and again in 1946. (The star’s next long-awaited flare-up is expected in 2024).

https://www.livescience.com/space/astronomy/evidence-of-mysterious-recurring-nova-that-could-reappear-in-2024-found-in-medieval-manuscript-from-1217

Related paper:

https://arxiv.org/abs/2308.13668
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/18/2023 06:42 pm
Quote
A team of astronomers has, for the first time, "weighed" dark matter haloes surrounding actively feeding supermassive black holes in the bright hearts of ancient galaxies.

Quote
And according to a new study, scientists suggest dark matter haloes around such active galaxies could help funnel matter toward the central black hole, acting as a cosmic delivery service helping feed the titans. This new work indicates that such a feeding mechanism was indeed at work around hundreds of ancient quasars and suggests the process is one that's  been constant throughout the history of the universe.

https://www.livescience.com/physics-mathematics/dark-matter/astronomers-measure-dark-matter-haloes-around-hundreds-of-ancient-black-holes-for-1st-time

Related paper:

https://iopscience.iop.org/article/10.3847/1538-4357/ace43a
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/21/2023 10:58 am
This Exoplanet is Probably a Solid Ball of Metal

Quote
Gliese 367 b (or Tahay) is certainly an oddball. It’s an Ultrashort Period (USP) planet that orbits its star in only 7.7 hours. There are almost 200 other USP planets in our 5000+ catalogue of exoplanets, so Gliese 367 b isn’t unique in that regard. But it’s an outlier in another way: it’s also an ultra-dense planet—almost twice as dense as Earth.

https://www.universetoday.com/163291/this-exoplanet-is-probably-a-solid-ball-of-metal/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/27/2023 10:57 pm
Precessing jet nozzle connecting to a spinning black hole in M87

Abstract
The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner region of M87 revealed a wide opening angle for the jet originating near the black hole1,2,3,4. The Event Horizon Telescope resolved the central radio source and found an asymmetric ring structure consistent with expectations from general relativity5. With a baseline of 17 years of observations, there was a shift in the jet’s transverse position, possibly arising from an 8- to 10-year quasi-periodicity3. However, the origin of this sideways shift remains unclear. Here we report an analysis of radio observations over 22 years that suggests a period of about 11 years for the variation in the position angle of the jet. We infer that we are seeing a spinning black hole that induces the Lense–Thirring precession of a misaligned accretion disk. Similar jet precession may commonly occur in other active galactic nuclei but has been challenging to detect owing to the small magnitude and long period of the variation.

https://www.nature.com/articles/s41586-023-06479-6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 09/28/2023 10:55 pm
Quote
Astronomers have used the observations by the Gaia satellite from the European Space Agency (ESA) to work out exactly how much mass the Milky Way has. And it turns out it is less than previous estimates, placing the total at 206 billion times the mass of our Sun.

https://www.iflscience.com/milky-way-weighs-less-than-we-thought-and-its-missing-dark-matter-70902

Related paper:

https://www.aanda.org/component/article?access=doi&amp;doi=10.1051/0004-6361/202347513
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 10/02/2023 02:00 pm
I wonder if some media outlets have jumped the gun on this as the relevant image doesn’t appear on the ESA website, nor is there any sign of the preprint yet.

[snip]
The BBC has a similar article where it mentions that the arxiv preprints on these Jumbos are expected Tuesday. So let’s wait. https://www.bbc.co.uk/news/science-environment-66974738

In the meantime, I seem to recall that some brown dwarfs also travel in pairs.
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 10/02/2023 08:47 pm
I wonder if some media outlets have jumped the gun on this as the relevant image doesn’t appear on the ESA website, nor is there any sign of the preprint yet.

[snip]
The BBC has a similar article where it mentions that the arxiv preprints on these Jumbos are expected Tuesday. So let’s wait. https://www.bbc.co.uk/news/science-environment-66974738

In the meantime, I seem to recall that some brown dwarfs also travel in pairs.
On the brown dwarf binary system, below is a link to a survey paper where they refer to Very Low Mass (VLM) binaries. Wouldn't it be cool if the Orion nebula enables us to detect many more pairs of "smaller than brown dwarf" objects (aka VERY Very Low Mass (VVLMs) ) which then leads to new planetary formation mechanisms? All speculation on my side of course but it seems it is an exciting discovery. Looking forward to the Jumbo arxiv paper.

https://articles.adsabs.harvard.edu/pdf/2013MmSAI..84.1005K
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 10/03/2023 10:09 pm
I wonder if some media outlets have jumped the gun on this as the relevant image doesn’t appear on the ESA website, nor is there any sign of the preprint yet.

[snip]
The BBC has a similar article where it mentions that the arxiv preprints on these Jumbos are expected Tuesday. So let’s wait. https://www.bbc.co.uk/news/science-environment-66974738

In the meantime, I seem to recall that some brown dwarfs also travel in pairs.
The Arxiv paper on "Jupiter Mass Binary Objects in the Trapezium Cluster" aka JUMBOs is out at https://arxiv.org/abs/2310.01231 and posted in the update thread as well. (https://forum.nasaspaceflight.com/index.php?topic=55472.msg2528815#msg2528815)
Title: Re: Astronomy & Planetary Science Thread
Post by: Torbjorn Larsson, OM on 10/04/2023 07:12 pm
Quote
As aforementioned, scientists believe that Saturn’s rings formed more recently, and Teodoro et al.’s modeling agrees with this and is giving scientists insights into how ring systems and the moons around them form. However, there are still plenty of questions that need to be answered. For example, if some of Saturn’s current icy moons formed alongside the rings and are also young, what would that mean for icy moons like Enceladus that could potentially host life within their sub-surface oceans?
https://www.nasaspaceflight.com/2023/10/saturn-rings/
Life evolved so quickly and diversify so prodigiously so a 100 Myrs should be enough.

But as it happens, a new method for dating the giant planet's moons make out Saturn's moons as old as the planet itself:
Quote
To address these questions, an international team of astronomers created a series of high-resolution simulations coupled with improved estimates of Trans-Neptunian Object (TNO) populations. This allowed them to construct a chronology of impacts for Saturn’s most heavily cratered regular satellites – Mimas, Enceladus, Tethys, Dione, and Rhea. This established age limits of 4.1 and 4.4 billion years for all five, with the two innermost moons appearing more youthful than the outer three. These results could have significant implications for our understanding of the formation and tidal evolution of moons in the outer Solar System.
https://www.universetoday.com/163104/whether-saturns-rings-are-young-or-old-its-moons-are-as-ancient-as-the-planet-itself/

Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 10/05/2023 11:01 pm
There could be a second Kuiper Belt just beyond the first one with a mysterious 10 AU gap between the two.

Quote
While using ground-based telescopes to hunt for fresh targets for NASA’s New Horizons spacecraft, now past Pluto on a course out of the Solar System, Fraser and his colleagues have made a tantalizing, though preliminary, discovery: about a dozen objects that lie beyond 60 AU—nearly as far from Pluto as Pluto is from the Sun. The finding, if real, could suggest that the Kuiper belt either extends much farther than once thought or—given the seeming 10-AU gap between these bodies and the known Kuiper belt—that a “second” belt exists.

https://www.science.org/content/article/puzzling-objects-found-far-beyond-neptune-hint-second-kuiper-belt
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/07/2023 10:27 am
No planet nine just MOND.

Quote
A pair of theoretical physicists are reporting that the same observations inspiring the hunt for a ninth planet might instead be evidence within the solar system of a modified law of gravity originally developed to understand the rotation of galaxies.

https://www.eurekalert.org/news-releases/1003878
Title: Re: Astronomy & Planetary Science Thread
Post by: Phil Stooke on 10/07/2023 07:01 pm
"The authors caution that the current dataset is small and that that any number of other possibilities might prove to be correct; other astronomers have argued the orbital peculiarities are the result of observational bias, for example."

So no actual evidence either way, just that the observed distribution of those few small objects is consistent with this new suggestion. 

I am more intrigued by the suggestion that there was a planet 9 but it was ejected from the solar system long ago:

https://twitter.com/elakdawalla/status/1709608894954160203 (https://twitter.com/elakdawalla/status/1709608894954160203)

(or should I call it Planet X?  Or even Planet Twitter?)
Title: Re: Astronomy & Planetary Science Thread
Post by: deadman1204 on 10/09/2023 02:23 pm
No planet nine just MOND.

Quote
A pair of theoretical physicists are reporting that the same observations inspiring the hunt for a ninth planet might instead be evidence within the solar system of a modified law of gravity originally developed to understand the rotation of galaxies.

https://www.eurekalert.org/news-releases/1003878
why do people persist on this. I understand studying gravity to make sure we understand it. However MOND has these gaping holes where its totally unable to explain large bodies of evidence.
Title: Re: Astronomy & Planetary Science Thread
Post by: leovinus on 10/09/2023 03:14 pm
No planet nine just MOND.

Quote
A pair of theoretical physicists are reporting that the same observations inspiring the hunt for a ninth planet might instead be evidence within the solar system of a modified law of gravity originally developed to understand the rotation of galaxies.

https://www.eurekalert.org/news-releases/1003878
why do people persist on this. I understand studying gravity to make sure we understand it. However MOND has these gaping holes where its totally unable to explain large bodies of evidence.
My thoughts exactly. Extraordinary (string, MOND) theory needs extraordinary evidence and that does not exist.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/09/2023 04:29 pm
Quote
An international team of scientists have discovered a huge spike in radiocarbon levels 14,300 years ago by analyzing ancient tree-rings. The radiocarbon spike was caused by a massive solar storm, the biggest ever identified.



Quote
Nine such extreme solar storms—known as Miyake Events—have now been identified as having occurred over the last 15,000 years studying tree-rings and ice layers records. The most recent confirmed Miyake Events occurred 1,030 and 1,250 years ago. This newly-identified 14,300-year-old storm is, however, the largest that has ever been found—roughly twice the size of these two.

https://www.forbes.com/sites/davidbressan/2023/10/09/tree-rings-show-extremely-powerful-solar-storm-hit-earth-14300-years-ago/?sh=3323b476a7cd

Related paper:

https://royalsocietypublishing.org/doi/10.1098/rsta.2022.0206
Title: Re: Astronomy & Planetary Science Thread
Post by: Barley on 10/09/2023 05:31 pm
why do people persist on this. I understand studying gravity to make sure we understand it. However MOND has these gaping holes where its totally unable to explain large bodies of evidence.
Because scholasticism is a bad look.

The way to shoot down bad arguments/evidence is with better arguments, not appeals to authority.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/12/2023 06:56 pm
Quote
Mysterious and rapid blasts of radiation that sweep over Earth could be the result of starquakes on "dead stars," or neutron stars. This connection could help scientists better understand earthquakes here on our planet.

https://www.space.com/starquakes-neutron-stars-radiation-bursts
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/14/2023 04:25 pm
Quote
The afterglow of a massive collision between two giant planets may have been detected for the first time. The wreckage of the collision could eventually cool and form an entirely new planet. If the observation is confirmed, it provides an amazing opportunity to watch the birth of a new world in real time and open a window into how planets form.

https://theconversation.com/the-afterglow-of-an-explosive-collision-between-giant-planets-may-have-been-detected-in-a-far-off-star-system-215466
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/23/2023 08:26 am
Quote
Record concentrations of a helium isotope found inside 62-million-year-old Arctic rocks could be the most compelling evidence to date of a slow leak in our planet's core.

Building on the results of a previous analysis of ancient lava flows, a team of geochemists from Woods Hole Oceanographic Institution and the California Institute of Technology are now more certain than ever that helium trapped in the core as our planet was forming is making its way to the surface.



Quote
Basaltic lavas on Canada's Baffin Island contain some of the world's highest ratios of helium 3 (3He) to the slightly heavier isotope, helium 4 (4He). To geologists, such a mix indicates the gas's presence isn't contamination by the atmosphere, but rather a sign of deeper, more ancient origins.

Several years ago, Woods Hole Oceanographic Institution geochemist Forrest Horton uncovered helium isotope ratios of up to 50 times that of atmospheric levels in samples of olivine collected from Baffin's lava fields, making them high even for the mantle.

https://www.sciencealert.com/our-planets-core-seems-to-be-leaking-and-scientists-think-they-know-why

Related paper:

https://www.nature.com/articles/s41586-023-06590-8
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/23/2023 04:36 pm
The Moon is 40 million years older than previously thought new analysis of crystals brought back by Apollo 17 has shown.

https://phys.org/news/2023-10-moon-million-years-older-thought.amp

Related paper:

https://www.geochemicalperspectivesletters.org/article2334/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/24/2023 08:11 am
Quote
An international team of researchers led by Dutch Ph.D. candidate Mark Snelders (ASTRON and University of Amsterdam) has discovered radio pulses from the distant universe that last only millionths of a second. They found these microsecond bursts after a meticulous examination of archival data from a known millisecond source. It's unclear how the ultrafast bursts are created.

https://phys.org/news/2023-10-astronomers-telescope-archive-microsecond-duration.html

Related paper:

https://arxiv.org/abs/2307.02303
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 10/24/2023 04:32 pm
Quote
The first super-Earth astronomers ever discovered has given off strange signals for nearly two decades, and scientists may have finally figured out why.



Quote
In the new study, the authors hypothesize that the planet's proximity to its star is causing it to outgas, meaning that giant volcanoes and thermal vents open up, spewing hot carbon-rich elements into the atmosphere. But the planet can't hold on to that atmosphere for long due to the extreme heat, and this gas eventually gets blown away, leaving the planet bare until the outgassing begins again.

Unlike most planets, the atmosphere of 55 Cancri e is unstable. The outgassing process tries to bulk up the atmosphere, while the extreme radiation and solar wind from the star blow it away. But these two processes are not in balance, leading to the situation where sometimes the planet has an atmosphere, and other times it doesn't.

The researchers believe this imbalance in the planetary atmosphere can explain the strange transit signals. When the planet is in its atmosphere-less "bald" phase, no visible light comes  from the planet's atmosphere, because there isn't one, but the planet's hot surface still emits infrared light. When the atmosphere puffs up, both the visible light and all the radiation coming from the surface show up in the transit signal.

https://www.space.com/james-webb-space-telescope-hell-planet-mystery-signals
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/02/2023 08:09 am
Stars Like Our Sun May Still Support Life After They Die. There's Just One Problem.

https://www.sciencealert.com/stars-like-our-sun-may-still-support-life-after-they-die-theres-just-one-problem

Related paper:

https://arxiv.org/abs/2310.15219
Title: Re: Astronomy & Planetary Science Thread
Post by: JulesVerneATV on 11/02/2023 02:27 pm
Bullying Jupiter-like planets may push 'alien Earths' away from life-friendly orbits

https://www.space.com/jupiter-size-planets-earth-orbit-gravity-study
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/03/2023 09:07 am
Quote
Now, a team of researchers has shed new light on a seven-planet system in Kepler’s ocean of data.

The star is called Kepler 385, and it’s about 4,670 light-years away. Some of its planets were confirmed back in 2014, while some remained as candidates. But in a new updated catalogue, exoplanet scientists have confirmed the rest of the planets and revealed new details on this rare system.



Quote
“Our revision to the Kepler Exoplanet catalogue provides the first true uniform analysis of exoplanet properties,” said co-author Jason Rowe, Canada Research Chair in Exoplanet Astrophysics and Professor at Bishop’s University in Quebec, Canada. “Improvements to all planetary and stellar properties have allowed us to conduct an in-depth study of the fundamental properties of exoplanetary systems to better understand exoplanets and directly compare these distant worlds to our own Solar System and to focus in on the details of individual systems such as Kepler-385.”

https://www.universetoday.com/164040/old-data-from-kepler-turns-up-a-system-with-seven-planets/

Related paper:

https://arxiv.org/abs/2311.00238
Title: Re: Astronomy & Planetary Science Thread
Post by: JulesVerneATV on 11/03/2023 12:45 pm
With so many findings in old photos, it sounds like a great place for Artificial Intelligence to take over old data and pictures and see what the human missed
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/04/2023 08:10 am
Massive anomaly within Earth's mantle may be remnant of collision that formed moon

Quote
An interdisciplinary international research team has recently discovered that a massive anomaly deep within the Earth's interior may be a remnant of the collision about 4.5 billion years ago that formed the moon.



Quote
According to Dr. Yuan, "Through precise analysis of a wider range of rock samples, combined with more refined giant impact models and Earth evolution models, we can infer the material composition and orbital dynamics of the primordial Earth, Gaia, and Theia. This allows us to constrain the entire history of the formation of the inner solar system."

Prof. Deng sees an even broader role for the current study. "This research even provides inspiration for understanding the formation and habitability of exoplanets beyond our solar system."

https://phys.org/news/2023-11-massive-anomaly-earth-mantle-remnant.html

Related video:

https://youtu.be/K0XO06EqnvU

And related paper:

https://www.nature.com/articles/s41586-023-06589-1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/04/2023 08:12 am
With so many findings in old photos, it sounds like a great place for Artificial Intelligence to take over old data and pictures and see what the human missed
I’m sure I’ve posted up a paper in the Gaia thread where that’s been done with data from that mission.
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/07/2023 09:52 am
Quote
A supermassive black hole smack-bang in the Cosmic Dawn has broken the record for the earliest black hole we've ever seen.

It's been spotted in a galaxy known as UHZ1, just 470 million years after the Big Bang, a time period when the Universe was still just a baby. In fact, it's so early in the Universe that the black hole is at a stage of development we've never seen before – it's of a similar mass to the host galaxy that is growing around it.



Quote
The discovery, according to a team led by astrophysicist Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA), constitutes key evidence for the mode of supermassive black hole formation that requires the direct gravitational collapse of a huge cloud of gas into an ultradense object that then grows larger and larger as time marches on.

https://www.sciencealert.com/earliest-black-hole-ever-spotted-at-the-dawn-of-time-and-its-already-huge

Related video:

https://youtu.be/zgGJY7ZlnSM

And related paper:

https://arxiv.org/abs/2305.15458
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/08/2023 04:05 pm
Direct detection of atomic oxygen on the dayside and nightside of Venus

Abstract
Atomic oxygen is a key species in the mesosphere and thermosphere of Venus. It peaks in the transition region between the two dominant atmospheric circulation patterns, the retrograde super-rotating zonal flow below 70 km and the subsolar to antisolar flow above 120 km altitude. However, past and current detection methods are indirect and based on measurements of other molecules in combination with photochemical models. Here, we show direct detection of atomic oxygen on the dayside as well as on the nightside of Venus by measuring its ground-state transition at 4.74 THz (63.2 µm). The atomic oxygen is concentrated at altitudes around 100 km with a maximum column density on the dayside where it is generated by photolysis of carbon dioxide and carbon monoxide. This method enables detailed investigations of the Venusian atmosphere in the region between the two atmospheric circulation patterns in support of future space missions to Venus.

https://www.nature.com/articles/s41467-023-42389-x
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/12/2023 06:39 am
Quote
The white dwarf WD 0810-353 –– the hot and dense corpse of a Sun-like star –– was set for a close encounter with our Solar System in just 29 000 years, the blink of an eye on evolutionary and cosmic time scales. Now, however, using ESO’s Very Large Telescope (VLT), astronomers have found that the dead star isn’t coming our way after all. Breathe a sigh of relief, humanity.



Quote
“We found that the approach speed measured by the Gaia project is incorrect, and the close encounter predicted between WD0810-353 and the Sun is actually not going to happen,” says Stefano Bagnulo, an astronomer at Armagh and co-author of the study. “In fact, WD0810-353 may not even be moving towards the Sun at all.”

https://www.eso.org/public/blog/rogue-star/?lang
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/15/2023 11:19 pm
Quote
But scientists are gaining a fuller understanding of Eris and its differences with Pluto thanks to research that discerns details about this frigid remote world's internal structure and composition based on its orbital relationship with its moon Dysnomia.

Eris, the researchers said on Wednesday, appears to have a rocky interior below a shell of ice. Pluto also has an icy exterior with rock below, but possesses a higher ice content and is thought to harbor an underground liquid ocean.

https://www.reuters.com/science/scientists-discern-internal-structure-mysterious-dwarf-planet-eris-2023-11-15/

Related paper:

https://www.science.org/doi/10.1126/sciadv.adi9201
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 11/16/2023 08:36 pm
Quote
The Hubble Space Telescope has measured the diameter of the nearest transiting exoplanet to us, discovering that it is a rocky planet very similar in size to Earth. Unfortunately, however, the world's surface is far too hot to support liquid water or life as we know it.



Quote
The more massive the planet, the larger the wobble; ESPRESSO measured the mass of LTT 1445Ac to be 1.37 times the mass of Earth.

Knowing its radius and its mass, it was then a simple matter to calculate LTT 1445Ac’s density, which came out to 5.9 grams per cubic centimeter. Earth, by comparison, has an average density of 5.51 grams per cubic centimeter. All in all, LTT 1445Ac is a little larger, a little denser and somewhat more massive than our planet, with a surface gravity 1.37 times greater than on Earth (a surface gravitational acceleration of 13.4 meters per second squared compared to Earth's 9.8 meters per second squared).

https://www.space.com/hubble-telescope-earth-size-exoplanet-transit

Related paper:

https://iopscience.iop.org/article/10.3847/1538-3881/acf561
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/24/2023 06:29 am
Quote
A high-energy particle falls from space to the Earth’s surface—it is not clear where it came from or even what it is, exactly. This may sound like something out of science fiction, but it is in fact a scientific reality, as evidenced by the research led by Associate Professor Toshihiro Fujii from the Graduate School of Science and Nambu Yoichiro Institute of Theoretical and Experimental Physics at Osaka Metropolitan University.

https://www.eurekalert.org/news-releases/1008434
Title: Re: Astronomy & Planetary Science Thread
Post by: Stan-1967 on 11/28/2023 12:53 am
Great Planetary Science article yesterday posted to NSF.
https://www.nasaspaceflight.com/2023/11/shrinking-subneptunes/
The original paper is linked at the end of the article.

Has anyone modeled the what the evaporation of a planetary scale atmosphere of a sub-Neptune like object would look like when transiting across a stellar disk as viewed from earth? 

I could not help but wonder if an evaporating sub-neptune is a better candidate for the brightness dips in something like a KIC 8462852 object?  That star is F class, so it would be very hostile to an atmosphere of a low gravity sub-neptune at a distance of 2-5 Au & periodicity ( 4.31 yr)  reported for the dips in that star system. 

I could not find a source for the age of KIC 8462852, other than it is at typical main sequence F class star.  If it is young, it's planets could still be migrating inwards or outwards depending on the overall system.

Our sun took care of a small martian atmosphere in a few hundred million years,  so I find it interesting to imagine what Mars would have looked like as it lost it's atmosphere, then multiply that by a Neptune sized object with a similar small rocky core as Mars.  It does not seem implausible to think a sub neptune could be loosing enormous amounts of matter for a hundred of millions years or so. 

The next dip in KIC 8462852 should be coming up within the next month or two.  What observations would be informative for this hypothesis?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2023 07:29 pm
This is the first time such a stellar disc has been found outside our galaxy:

Stellar disc discovered in another galaxy! (ESOCast 268 Light)

https://youtu.be/D0EKI0FKciI?si=0jJa3WiUfKqDq90K
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/29/2023 11:03 pm
Quote
Six planets that orbit their star in a coordinated dance have been discovered by scientists, who say the finding could help shed light on why planets in our own solar system move to their own beat.

https://www.theguardian.com/science/2023/nov/29/planets-of-distant-solar-system-orbit-star-in-coordinated-dance-say-scientists

Related paper:

https://www.nature.com/articles/s41586-023-06692-3.epdf?
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/30/2023 06:54 pm
‘Horde of dead stars!’ Spider Pulsars caught destroying nearby stars:

https://youtu.be/B2PL55vsqiE?si=oJeRedr55nEJqlEX
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 11/30/2023 11:20 pm
This planet is so large in comparison to its host star that it challenges our theories of planetary formation.

Quote
Astronomers are questioning the theories of planet formation after discovering an exoplanet that technically shouldn’t exist.

The planet, about the mass of Neptune and more than 13 times as massive as Earth, was detected orbiting an ultracool M-dwarf star called LHS 3154 — which is nine times less massive than our sun. An M-dwarf star is the smallest and coolest type of star.

https://amp.cnn.com/cnn/2023/11/30/world/neptune-exoplanet-small-star-scn/index.html

Related paper:

https://www.science.org/doi/10.1126/science.abo0233
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/05/2023 06:23 am
Dwarf planet Eris is squishier than expected

https://news.ucsc.edu/2023/11/nimmo-eris.html

Related paper:

https://www.science.org/doi/10.1126/sciadv.adi9201
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/07/2023 11:42 am
Quote
The vicinity of a supermassive black hole is thought to be way too extreme and messy to allow for star formation, so astronomers believe that any stars hanging about there must have come from somewhere else.

Well, now a team led by astrophysicist Shogo Nishiyama of Miyagi University of Education has determined the origins of one of those stars, named S0-6 – and found that it's decidedly not from around here.

In fact, S0-6 appears to be from outside the Milky Way entirely, making it the first star in the galactic center found to have an extragalactic origin story.

https://www.sciencealert.com/mysterious-star-at-heart-of-milky-way-appears-to-be-from-alien-galaxy

Related paper:

https://www.jstage.jst.go.jp/article/pjab/advpub/0/advpub_pjab.100.007/_article
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/07/2023 07:38 pm
JWST shows the early Universe is different than we thought (that’s a good thing)

https://youtu.be/FjWwQEDq0KU?si=jRmgjOpho-Jn7WMW
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/12/2023 07:54 pm
Attempting to counter some of sensationalist headlines you see online around strange matter.

Could Quark Stars be the Engines of Self-Replicating Strange Matter?

https://youtu.be/iNiE293-EvE?si=K6zhMDCev91bxKJH
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/12/2023 11:09 pm
Scientists Found Evidence Of A Nearby Kilonova 3.5 Million Years Ago

Quote
Most of the times astronomers reported dramatic, cataclysmic events like neutron star mergers or the creation of a black hole; they are taking place light years away, typically in in another galaxy. While we can observe their destructive power through the light they emit, they have minimal impact on Earth. However, a relatively recent discovery of certain types of isotopes at the bottom of the ocean hints at one of these events happening fairly close to home. And it probably didn’t happen all that long ago.

https://www.universetoday.com/164716/scientists-found-evidence-of-a-nearby-kilonova-3-5-million-years-ago/

Related paper:

https://arxiv.org/abs/2311.17159
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/14/2023 04:44 pm
PBS have now made a short documentary about the Silurian hypothesis:

https://youtu.be/vyEWLhOfLgQ?si=BjRkhs8trDvSPG3A
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/15/2023 04:31 pm
Mysterious fast radio bursts in space keep getting stranger

https://edition.cnn.com/2023/12/14/world/repeating-fast-radio-burst-quirk-scn/index.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/19/2023 04:35 pm
Quote
Something peculiar is going on a long way beneath our feet. The rotation of the Earth's inner core is not aligned with the rotation of the mantle, creating a wobble that affects the motion of the poles and even the length of the days that our planet experiences.



Quote
The new work suggests that the rotation axis of the inner core is 0.17 degrees off compared to the rotation of the mantle.



Quote
Since the late 1980s, researchers have suspected that a coupling between the inner core and the mantle could be responsible for a periodic variation on the order of 10 years. This study puts the wobble at 8.5 years, plus or minus 75 days. It was the discovery of a signal in the polar motion back in 2018, combined with the day-length fluctuations, that led the researchers to conclude that they were being caused by the same process, a small misalignment.

https://www.iflscience.com/an-85-year-long-wobble-means-earths-core-and-mantle-are-not-aligned-72087

Related paper:

https://www.nature.com/articles/s41467-023-43894-9
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 12/29/2023 04:29 pm
Some Icy Exoplanets May Have Habitable Oceans and Geysers

Quote
“Our analyses predict that these 17 worlds may have ice-covered surfaces but receive enough internal heating from the decay of radioactive elements and tidal forces from their host stars to maintain internal oceans,” said Dr. Lynnae Quick of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Thanks to the amount of internal heating they experience, all planets in our study could also exhibit cryovolcanic eruptions in the form of geyser-like plumes.” Quick is lead author of a paper on the research published on October 4 in the Astrophysical Journal.



Quote
They predict that surface temperatures are colder than previous estimates by up to 60 degrees Fahrenheit (about 33 degrees Celsius). Estimated ice shell thickness ranged from about 190 feet (58 meters) for Proxima Centauri b and one mile (1.6 kilometers) for LHS 1140 b to 24 miles (38.6 kilometers) for MOA 2007 BLG 192Lb, compared to Europa’s estimated average of 18 miles (almost 29 kilometers). Estimated geyser activity went from just 17.6 pounds per second (about 8 kilograms/second) for Kepler 441b to 639,640 pounds/second (290,000 kilograms/second) for LHS 1140 b and 13.2 million pounds/second (six million kilograms/second) for Proxima Centauri b, compared to Europa at 4,400 pounds/second (2,000 kilograms/second).



Quote
For planets like Proxima Centauri b that don’t cross their stars from our vantage point, geyser activity could be detected by powerful telescopes that are able to measure light that the exoplanet reflects while orbiting its star. Geysers would expel icy particles at the exoplanet’s surface which would cause the exoplanet to appear very bright and reflective.

https://www.nasa.gov/science-research/planetary-science/astrobiology/nasa-some-icy-exoplanets-may-have-habitable-oceans-and-geysers/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/09/2024 04:33 pm
Quote
Researchers may have identified the missing component in the chemistry of the Venusian clouds that would explain their colour and 'splotchiness' in the UV range, solving a longstanding mystery.

https://www.cam.ac.uk/research/news/mysterious-missing-component-in-the-clouds-of-venus-revealed

Related paper:

https://www.science.org/doi/10.1126/sciadv.adg8826
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/10/2024 07:05 am
This new paper theorises that the Sun may have picked up one or more wandering planets and added them to the outer solar system.

Quote
Now, theoretical astrophysicist Amir Siraj of Princeton University has worked out just how many alien planets might be out there, hidden from our view. According to his calculations, on a purely mathematical level, there could be 1.2 planets with a mass greater than Mars; 2.7 with a mass comparable to Mars; and 5.2 with a mass comparable to that of Mercury.

These are just educated guesses, based on other educated guesses, but the idea that there could be just one hidden world out there that has traveled from a distant star is certainly a fascinating one.

https://www.sciencealert.com/there-could-be-alien-mars-sized-planets-lurking-beyond-pluto

Here’s the actual paper:

https://iopscience.iop.org/article/10.3847/2041-8213/ad13eb
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/11/2024 04:27 pm
Quote
An exoplanet orbiting a small star some 50 light-years away from Earth may be a life-friendly water world, a new study has revealed — and the James Webb Space Telescope could determine if that is indeed the case.

The planet in question, called LHS 1140b, orbits in the habitable zone of a small, dim star called LHS 1140 that lies in the constellation Cetus. The exoplanet was discovered in 2017 and has been observed by multiple telescopes since.

These observations first convinced researchers that LHS 1140b is a rocky planet about 1.7 times wider than Earth. But a new analysis of all available observations has shown that LHS 1140b is not dense enough to be purely rocky and must either contain much more water than Earth or possess an extensive atmosphere full of light elements such as hydrogen and helium.

https://www.space.com/exoplanet-lhs-1140b-habitable-zone-water

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/ad1691
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/11/2024 11:10 pm
Quote
Astronomers have discovered a ring-shaped cosmic megastructure, the proportions of which challenge existing theories of the universe.

The so-called Big Ring has a diameter of about 1.3bn light years, making it among the largest structures ever observed. At more than 9bn light years from Earth, it is too faint to see directly, but its diameter on the night sky would be equivalent to 15 full moons.

The observations, presented on Thursday at the 243rd meeting of the American Astronomical Society in New Orleans, are significant because the size of the Big Ring appears to defy a fundamental assumption in cosmology called the cosmological principle. This states that above a certain spatial scale, the universe is homogeneous and looks identical in every direction.

https://www.theguardian.com/science/2024/jan/11/newly-discovered-cosmic-megastructure-challenges-theories-of-the-universe
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/12/2024 08:21 am
Quote
Astronomers have discovered an unusual Earth-sized exoplanet they believe has a hemisphere of molten lava, with its other hemisphere tidally locked in perpetual darkness. Co-authors and study leaders Benjamin Capistrant (University of Florida) and Melinda Soares-Furtado (University of Wisconsin-Madison) presented the details yesterday at a meeting of the American Astronomical Society in New Orleans. An associated paper has just been published in The Astronomical Journal. Another paper published today in the journal Astronomy and Astrophysics by a different group described the discovery of a rare small, cold exoplanet with a massive outer companion 100 times the mass of Jupiter.

https://arstechnica.com/science/2024/01/some-like-it-hot-astronomers-spot-an-earth-sized-exoplanet-thats-half-lava/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/16/2024 06:27 pm
Quote
Astronomers have discovered a pair of exoplanets orbiting an M dwarf star, one of which is the coldest M dwarf planet found by the TESS satellite observatory, making it accessible for follow-up studies of its atmosphere. The work is published in The Astrophysical Journal Letters.

https://phys.org/news/2024-01-twins-cousins-neptune-exoplanets.html

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/ad037d
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/18/2024 08:09 am
Quote
Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered nine new "hot Jupiter" exoplanets. One of the newly detected alien worlds is almost four times more massive than Jupiter. The finding was presented in a paper published January 11 on the pre-print server arXiv.

https://phys.org/news/2024-01-tess-hot-jupiters.html

Related paper:

https://arxiv.org/abs/2401.05923
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/18/2024 04:27 pm
Quote
A global team of astronomers have created the most sensitive radio image ever of a globular cluster, an ancient ball of tightly-packed stars.

https://www.icrar.org/47tuc/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/19/2024 06:29 am
Quote
A team of scientists found a compact object 40,000 light-years from Earth that is either a very massive neutron star or an itsy-bitsy black hole, but they’re not sure which.

https://gizmodo.com/mystery-space-object-biggest-neutron-star-black-hole-1851176506

Related paper:

https://www.science.org/doi/10.1126/science.adg3005
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/25/2024 11:14 pm
Quote
Astronomers have discovered a mysterious group of giant elderly stars at the heart of the Milky Way that are emitting solar system-sized clouds of dust and gas.

The stars, which have been named “old smokers”, sat quietly for many years, fading almost to invisibility, before suddenly puffing out vast clouds of smoke. The discovery was made during the monitoring of almost a billion stars in infrared light during a 10-year survey of the night sky.

https://www.theguardian.com/science/2024/jan/26/old-smokers-astronomers-discover-giant-ancient-stars-in-milky-way?CMP=Share_iOSApp_Other

Related paper:

https://academic.oup.com/mnras/article/528/2/1789/7589621
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/29/2024 08:53 pm
Quote
A team of scientists, using cutting-edge technology, has uncovered a fascinating star system named TOI-1136 in the Milky Way galaxy.

Located over 270 light years from Earth, this system, surprisingly close given the vast 100,000 light-year diameter of our galaxy, hosts a family of six, possibly seven, planets orbiting a dwarf star.

https://www.earth.com/news/six-planet-system-discovered-just-270-light-years-away-named-toi-1136/

Related paper:

https://arxiv.org/abs/2312.04635
Title: Re: Astronomy & Planetary Science Thread
Post by: Zed_Noir on 01/30/2024 02:36 am
Quote
A team of scientists, using cutting-edge technology, has uncovered a fascinating star system named TOI-1136 in the Milky Way galaxy.

Located over 270 light years from Earth, this system, surprisingly close given the vast 100,000 light-year diameter of our galaxy, hosts a family of six, possibly seven, planets orbiting a dwarf star.

https://www.earth.com/news/six-planet-system-discovered-just-270-light-years-away-named-toi-1136/

Related paper:

https://arxiv.org/abs/2312.04635

 :)
Have we discovered the Homeworld of Larry Niven's Puppeteers?
 :)
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 01/30/2024 09:42 pm
Have we discovered the Homeworld of Larry Niven's Puppeteers?
 :)

If so, we can hope they use one of their starseed lures to entice an Outsider ship to Earth so we can purchase the secret of hyperdrive technology from them - assuming we can afford it!
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 01/31/2024 08:40 am
Quote
Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a new ultra-short-period exoplanet. The newfound alien world, designated Wolf 327 b, is slightly larger and about 2.5 times more massive than the Earth. The finding was reported in a paper published January 22 on the pre-print server arXiv.



Quote
Summing up the results, the authors of the paper say this is an interesting addition to the known sample of USP planets orbiting M-dwarf stars, due to its interesting internal structure and favorable metrics for secondary transit detection with the James Webb Space Telescope (JWST). According to the authors, there is also a high probability that other planets also orbit Wolf 327, given that USPs are usually found in multi-planetary systems.

https://phys.org/news/2024-01-wolf-astronomers-ultra-short-period.html

Related paper:

https://arxiv.org/abs/2401.12150
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/01/2024 11:26 am
Quote
Meteorite hunters have tracked down fragments from an asteroid that struck the Earth over Berlin last week and it appears to be “very rare.”

Fragments of the small asteroid dubbed 2024 BX1 burned up in the skies above Berlin into a harmless fireball last Sunday merely two hours after it was discovered by astronomers.



Quote
Experts, including meteor scientist Peter Jenniskens, found the rock fragments to be “very rare” as they resemble rocks found on the Earth.

https://www.independent.co.uk/space/asteroid-berlin-very-rare-rock-b2488504.html
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/05/2024 07:00 pm
Quote
A “super-Earth” ripe for further investigation orbits a small, reddish star that is, by astronomical standards, fairly close to us – only 137 light-years away. The same system also might harbor a second, Earth-sized planet.

https://science.nasa.gov/universe/exoplanets/discovery-alert-a-super-earth-in-the-habitable-zone/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/07/2024 04:31 pm
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A surprisingly youthful ocean within Mimas, a tiny moon of Saturn, has big implications for the solar system’s history—and for finding life beyond Earth



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To find the ocean of Mimas, the study’s authors focused less on the moon’s surface detail and more on its motion, finding a telltale drift in its orbit via archival data from the Cassini spacecraft, which surveyed the Saturnian system for 13 years before concluding its mission in 2017. Some of Mimas’s drift, the researchers say, can only be explained if the layer-cake structure of the moon itself features an icy shell that slides around on top of a liquid-water ocean.



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“The implications for this are just enormous,” says Carly Howett, a planetary scientist at the University of Oxford, who was not involved with the new study. The first is that you shouldn’t judge a moon by its cover—oceans may grace other seemingly inert icy orbs, such as several satellites of Uranus and Neptune, scarcely explored planets that, like Saturn, lie in the outer solar system. The second implication is that icy-moon oceans need not be ancient and enduring; some could be incipient, transient seas.

https://www.scientificamerican.com/article/saturns-death-star-moon-may-hide-a-massive-shockingly-young-ocean/

Related paper:

https://www.nature.com/articles/s41586-023-06975-9.epdf
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/07/2024 11:23 pm
Could a Kilonova Kill: A Threat Assessment

Abstract
Binary neutron star mergers produce high-energy emissions from several physically different sources, including a gamma-ray burst (GRB) and its afterglow, a kilonova (KN), and, at late times, a remnant many parsecs in size. Ionizing radiation from these sources can be dangerous for life on Earth-like planets when located too close. Work to date has explored the substantial danger posed by the GRB to on-axis observers; here we focus instead on the potential threats posed to nearby off-axis observers. Our analysis is based largely on observations of the GW170817/GRB 170817A multi-messenger event, as well as theoretical predictions. For baseline KN parameters, we find that the X-ray emission from the afterglow may be lethal out to ∼1 pc and the off-axis gamma-ray emission may threaten a range out to ∼4 pc, whereas the greatest threat comes years after the explosion, from the cosmic rays accelerated by the KN blast, which can be lethal out to distances up to ∼11 pc. The distances quoted here are typical, but the values have significant uncertainties and depend on the viewing angle, ejected mass, and explosion energy in ways we quantify. Assessing the overall threat to Earth-like planets, KNe have a similar kill distance to supernovae, but are far less common. However, our results rely on the scant available KN data, and multi-messenger observations will clarify the danger posed by such events.

https://iopscience.iop.org/article/10.3847/1538-4357/ad12b7
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 02/09/2024 09:56 am
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A little moonlet, too small to be seen from Earth, could be playing cosmic sheepdog by shaping the thin rings around the distant minor planet Chariklo, according to new computer simulations.

https://www.space.com/chariklo-centaur-rings-shaped-by-tiny-moon
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/13/2024 11:25 pm
What We Know Now about TRAPPIST-1 (and what we don’t)

https://www.centauri-dreams.org/2024/02/09/what-we-know-now-about-trappist-1-and-what-we-dont/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/14/2024 06:51 pm
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Stars that pass by our solar system have altered the long-term orbital evolution of planets, including Earth, and, by extension, modified our climate.

https://phys.org/news/2024-02-stars-orbital-evolution-earth-planets.html

Simulation for star HD7977 that is believed past by 2.8 million years ago:

https://youtu.be/FlmoWuX-H3s

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/ad24fb
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/15/2024 04:32 pm
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A team co-led by Southwest Research Institute found evidence for hydrothermal or metamorphic activity within the icy dwarf planets Eris and Makemake, located in the Kuiper Belt. Methane detected on their surfaces has the tell-tale signs of warm or even hot geochemistry in their rocky cores, which is markedly different than the signature of methane from a comet.



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”After the New Horizons flyby of the Pluto system, and with this discovery, the Kuiper Belt is turning out to be much more alive in terms of hosting dynamic worlds than we would have imagined," said Glein. "It's not too early to start thinking about sending a spacecraft to fly by another one of these bodies to place the JWST data into a geologic context. I believe that we will be stunned by the wonders that await."

https://phys.org/news/2024-02-scientists-evidence-geothermal-icy-dwarf.html

Related paper:

https://www.sciencedirect.com/science/article/abs/pii/S0019103524000575?via%3Dihub
Title: Re: Astronomy & Planetary Science Thread
Post by: Blackstar on 02/18/2024 03:18 am
Maybe dwarf planets are active:

https://www.swri.org/press-release/swri-scientists-find-evidence-of-geothermal-activity-within-icy-dwarf-planets

This is interesting stuff. But I'm annoyed that their website does not clearly state that the images of the two dwarf planets are actually artwork, not photos taken by a telescope. I even downloaded the caption, which was empty. That's misleading.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/18/2024 11:15 pm
The Star That Shouldn’t Exist - Przybylski’s Star:

https://youtu.be/maMDGZOD3mI?si=PBdwIZ-pUY3lHvmO
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/19/2024 07:41 pm
Astronomers identify record breaking Quasar:

https://youtu.be/SXFvPcgMnuQ?si=8rU5Hvm-3MZQ86X6
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/20/2024 06:29 am
A new paper from Mike Brown and colleagues has further narrowed down where planet nine of it does exist could be hiding.

Quote
Dr. Mike Brown, who is a Richard and Barbara Rosenberg Professor of Astronomy at Caltech and lead author of the study, tells Universe Today, “We are continuing to try to systematically cover all of the regions of the sky where we predict Planet Nine to be. Using data from Pan-STARRS allowed us to cover the largest region to date.”



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In the end, the team narrowed down possible locations of Planet Nine by eliminating approximately 78 percent of possible locations that were calculated from previous studies. Additionally, the researchers also provided new estimates for the approximate semimajor axis (measured in astronomical units (AU)) and Earth-mass size of Planet Nine at 500 and 6.6, respectively. So, what are the most significant results from this study, and what follow-up studies are currently being conducted or planned?

“While I would love to say that the most significant result was finding Planet Nine, we didn’t,” Dr. Brown tells Universe Today. “So instead, it means that we have significantly narrowed the search area. We’ve now surveyed approximately 80% of the regions where we think Planet Nine might be.”



Quote
Dr. Brown tells Universe Today, “This would be the 5th largest planet of our solar system and the only one with a mass between Earth and Uranus. Such planets are common around other stars, and we would suddenly have a chance to study one in our own solar system.”

https://www.universetoday.com/165774/theres-one-last-place-planet-9-could-be-hiding/?utm_source=DamnInteresting#google_vignette

Here’s the paper:

https://arxiv.org/abs/2401.17977
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/22/2024 08:08 am
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Our Milky Way Galaxy may be as much as two billion years older than currently thought, the principal investigator of a unique multi-year project to simulate the galaxy’s origin and evolution, told me here in Santiago. In fact, our own 10-billion-year-old Milky Way may contain ancient stars that predate the galaxy and that are as old as the cosmos itself.

A collaboration between Argentina, Chile and Spain called CIELO: Chemo-dynamical Properties of Galaxies and the Cosmic Web ("cielo" is “sky" in Spanish), the team’s research predates the covid pandemic and will continue for at least another five years.

https://www.forbes.com/sites/brucedorminey/2024/02/21/our-milky-way-may-be-two-billion-years-older-than-currently-thought/
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/25/2024 10:35 am
The theory of Dark Energy stars:

https://youtu.be/Oj9nJFqios4?si=K1P4Fu99NZjBPdd3
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/26/2024 06:19 am
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The Solar System has some new lunar members—the first new moon of Uranus discovered in more than 20 years, and likely the smallest, as well as two new moons of Neptune, one of which is the faintest moon ever discovered by ground-based telescopes. The discoveries were announced today by the International Astronomical Union's Minor Planet Center.



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All of the new Uranian and Neptunian moons have distant, eccentric, and inclined orbits that suggests they were captured by the gravity of these planets during or shortly after Uranus and Neptune formed from the ring of dust and debris that surrounded our Sun in its infancy. All of the giant planets in our Solar System have similar configurations for their outer moons, regardless of their size or the process by which they formed.

https://carnegiescience.edu/new-moons-uranus-and-neptune-announced
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/26/2024 06:53 pm
Quote
Astronomers have spotted a star with a dark metallic “scar” on its surface, thought to be the imprint of a doomed planetary fragment that came too close to its host.
The white dwarf star, called WD 0816-310, is a dense, Earth-sized remnant of a star about 63 light years away that would have been similar to our sun in its lifetime. Observations revealed a concentrated patch of metals on its surface, which appear to be the remnants of an ingested chunk of planet or an asteroid.

https://amp.theguardian.com/science/2024/feb/26/astronomers-white-dwarf-star-metallic-scar

Related paper:

https://www.eso.org/public/archives/releases/sciencepapers/eso2403/eso2403a.pdf
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 02/28/2024 11:49 am
More news recently came out about Trappist-1: planet e is reported to have active atmospheric loss due to shenanigans with the magnetic field and its rapid orbit amplifying ionizing stripping.  It's making the case for atmospheres on any of the known planets looks unlikely.

https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping (https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping)
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2024 02:08 pm
More news recently came out about Trappist-1: planet e is reported to have active atmospheric loss due to shenanigans with the magnetic field and its rapid orbit amplifying ionizing stripping.  It's making the case for atmospheres on any of the known planets looks unlikely.

https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping (https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping)
Doesn’t say much for chances of atmospheres on planets around Proxima Centauri either.
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 02/28/2024 04:19 pm
More news recently came out about Trappist-1: planet e is reported to have active atmospheric loss due to shenanigans with the magnetic field and its rapid orbit amplifying ionizing stripping.  It's making the case for atmospheres on any of the known planets looks unlikely.

https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping (https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping)
Doesn’t say much for chances of atmospheres on planets around Proxima Centauri either.

Definitely agree.  We're at the stage where these red dwarves are showing us the lower limits of habitable stars.  The overall lifetime of a star crosses out O, B, and at least most A-types from hosting complex, if not all forms, of life.  It might be the proximity/intensity of solar flares that sets the low point.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/28/2024 11:42 pm
More news recently came out about Trappist-1: planet e is reported to have active atmospheric loss due to shenanigans with the magnetic field and its rapid orbit amplifying ionizing stripping.  It's making the case for atmospheres on any of the known planets looks unlikely.

https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping (https://www.space.com/trappist-1-exoplanet-habitability-atmospheric-stripping)
Doesn’t say much for chances of atmospheres on planets around Proxima Centauri either.

Definitely agree.  We're at the stage where these red dwarves are showing us the lower limits of habitable stars.  The overall lifetime of a star crosses out O, B, and at least most A-types from hosting complex, if not all forms, of life.  It might be the proximity/intensity of solar flares that sets the low point.
It doesn’t help that they take a huge amount of time to settle down, aren’t the more calm examples we’ve found all extremely old?
Title: Re: Astronomy & Planetary Science Thread
Post by: redliox on 02/29/2024 04:27 am
It doesn’t help that they take a huge amount of time to settle down, aren’t the more calm examples we’ve found all extremely old?

If you're talking red dwarves and their flare activity, hard to say.  Proxima is supposed to be 6 BYO and still flares.  Given how small they are their catalog might be incomplete.  I was told part of their flare problem is the fact the mass of larger stars insulates their activity; sort of like imagining Earth's mantle suppressing super-volcanoes the core tries to generate.  Trappist-1 might be the equivalent of a toddler throwing its SpaghettiOs with abandon.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/29/2024 06:16 am
A more complete report on the recent update in the hunt for the supposed planet nine in the Solar System. This is sounding more like the non-existent planet Vulcan every time we get these negative updates from Mike Brown.

https://www.livescience.com/space/planets/astronomers-narrow-down-where-planet-nine-could-be-hiding-by-playing-massive-game-of-connect-the-dots
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 02/29/2024 03:49 pm
Quote
An exciting discovery could shed some light on how Earth got its water.

New observations of a disk of dust and gas circling a baby star have revealed a large amount of water vapor, at the exact location where baby planets might be starting to form.

https://youtu.be/YVfPKdginYU

https://www.sciencealert.com/in-a-science-first-astronomers-map-water-right-where-planets-are-expected-to-form

Related paper:

https://www.nature.com/articles/s41550-024-02207-w
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/01/2024 06:12 am
The Cool Worlds Lab have won time on JWST to study a very Jupiter like Exoplanet for Exomoons, and not just a small amount of time but seemingly what is a large amount of time some three days of telescope time, you can clearly tell how happy he is by this grant of time:

https://youtu.be/4sv_sa_tLPg?si=4YIP3luTw_Gyc7qQ

He states their target exoplanet is 2.2AU from its host star which is a K type. They had two other proposals that were rejected by high ranked. He also states that a team from Harvard has also been granted time to look for exomoons, but doesn’t know what their target is, and they have been granted less time than they have for their target.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/05/2024 06:19 am
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Astronomers have performed multi-wavelength photometric observations of a nearby planetary-mass object known as SIMP J013656.5+093347. Results of the observational campaign, presented February 22 on the pre-print server arXiv, suggest that the object hosts patchy cloud layers in its atmosphere.

https://phys.org/news/2024-03-evidence-patchy-cloud-layers-atmosphere.html

Related paper:

https://arxiv.org/abs/2402.15001
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/06/2024 06:22 am
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Some 100 light-years from the Solar System dwells the most mathematically perfect planetary system we've ever seen.

The star at its center – a temperate orange dwarf called HD 110067 – is orbited by six exoplanets, each of which travels in harmony with its adjacent worlds. Such a perfect chain of orbital resonances is extremely rare, and it means that the system has remained relatively stable and undisturbed since it formed, around a billion years ago.

https://www.sciencealert.com/perfectly-synchronized-planetary-system-probed-for-signs-of-alien-technology

Related paper:

https://iopscience.iop.org/article/10.3847/2515-5172/ad235f
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/06/2024 06:24 am
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Well, you can relax. Astronomers Paul Wiegert of Western University and Ben Hyatt of the University of Waterloo in Canada have projected the orbits of over 1.3 million known asteroids in the inner Solar System and reached a comforting conclusion: Not a single asteroid is going to collide with Apophis in the next few years.

"Given how closely Apophis will pass Earth, there is a possible risk that a deflection from its current trajectory may move Apophis closer to impacting us," Hyatt says.

"Hypothetically, another asteroid colliding with Apophis could cause such a deflection, motivating us to study this scenario however unlikely it may be."

https://www.sciencealert.com/astronomers-confirm-giant-asteroid-apophis-will-not-hit-earth

Related paper:

https://arxiv.org/abs/2403.00541
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/07/2024 04:30 pm
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For the first time, scientists have been able to explain the mystery behind the unusual chemical composition in one of the universe's most distant galaxies. The state-of-the-art theoretical model that the breakthrough research has established could be a key to our better understanding of the far universe.



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But Professor Kobayashi's research has not only disproved that hypothesis of super-massive stars and possibly also the remnant super-massive black hole. Instead, she has established a new means of understanding early galaxies.

Professor Chiaki Kobayashi, professor of astrophysics at the University of Hertfordshire, said, "The galaxy is not telling us about an unusual star but an unusual episode of galaxy life. We found that early galaxies have 'bursty' star formation, which causes this unusual chemical composition. "

https://phys.org/news/2024-03-scientists-riddle-nitrogen-rich-galaxy.html

Related paper:

https://iopscience.iop.org/article/10.3847/2041-8213/ad1de1
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/08/2024 03:45 pm
Quote
Contentious claims that an interstellar meteor possibly containing alien technology hit Earth a decade ago is on even shakier ground – quite literally. Last year, pieces of the meteor were collected from the ocean off Papua New Guinea, though later analysis brought into question the "alien tech" nature of the spherules recovered. Now, it appears the soundwaves the team claimed were linked to the fireball were actually from the shaking of a nearby truck driving past.



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Now, a team from Johns Hopkins University argues that their seismic analysis is wrong too. What they linked to the meteor was "almost certainly" the motion of a truck moving on a nearby road. What's more, they put forward evidence that the meteor entered the atmosphere elsewhere and if fragments did land in the ocean they did so in a completely different place to where Loeb and team calculated.



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Based on their new analysis, Fernando’s team estimated that the more likely place for the meteor to have landed is over 160 kilometers (100 miles) from the area investigated.



Quote
But, you might say, they found "spherules" of alien origin! I read it online! Well, analysis from another researcher has already highlighted how the anomalous composition was consistent with human-made pollution, stating “the meteoritic evidence is disfavored.”

https://www.iflscience.com/interstellar-alien-tech-meteor-signal-was-actually-just-vibrations-of-local-truck-73299
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/09/2024 11:16 am
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Dark matter is supposed to account for 85% of the mass in the universe, according to conventional scientific wisdom. But proponents of a radical new theory of gravity, in which space-time is “wobbly”, say their approach could render the elusive substance obsolete.

The proposition, outlined in a new paper, raises the controversial possibility that dark matter, which has never been directly observed, is a mirage that a substantial portion of the physics community has been chasing for several decades. The theory is viewed as quite left-field and is yet to be thoroughly tested, but the latest claims are creating a stir in the world of physics.

Announcing the paper on X, Prof Jonathan Oppenheim, of University College London, said: “Folks, something seems to be happening. We show that our theory of gravity … can explain the expansion of the universe and galactic rotation without dark matter or dark energy.”

https://www.theguardian.com/science/2024/mar/09/controversial-new-theory-of-gravity-rules-out-need-for-dark-matter

Here’s the related paper:

https://arxiv.org/abs/2402.19459
Title: Re: Astronomy & Planetary Science Thread
Post by: CuddlyRocket on 03/09/2024 09:25 pm
Quote
Announcing the paper on X, Prof Jonathan Oppenheim, of University College London, said: “Folks, something seems to be happening. We show that our theory of gravity … can explain the expansion of the universe and galactic rotation without dark matter or dark energy.”

They were careful to note that "it is important to acknowledge the existence of separate, independent evidence supporting ΛCDM [Λ Cold Dark Matter]. In particular, in the CMB [Cosmic Microwave Background] power spectrum, in gravitational lensing, in the necessity of dark matter for structure formation, and in a varied collection of other methods used to estimate the mass in galaxies."

Which is the downfall of all modified General Relativity theories to date. But time will tell.
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/09/2024 10:48 pm
Quote
Indian astronomers have conducted long-term X-ray observations of a nearby ultra-fast rotating active star known as AB Doradus A. Results of the observational campaign, published February 29 on the pre-print server arXiv, provide crucial insights into the short-term and long-term variability of this star.

https://phys.org/news/2024-03-variability-nearby-ultra-fast-rotating.html

Related paper:

https://arxiv.org/abs/2402.19083
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/13/2024 04:33 pm
Quote
Scientists from the Universities of Sydney and Sorbonne University have used the geological record of the deep sea to discover a connection between the orbits of Earth and Mars, past global warming patterns and the speeding up of deep ocean circulation.

They discovered a surprising 2.4-million-year cycle where deep currents wax and wane which, in turn, is linked to periods of increased solar energy and a warmer climate.



Quote
They found that the vigour of deep-sea currents shifts in 2.4-million-year cycles.

These cycles are called “astronomical grand cycles”, predicted to occur due to the interactions of Earth and Mars orbits. However, evidence for this is rarely detected in the geological record.

https://www.eurekalert.org/news-releases/1037006

Related paper:

https://www.nature.com/articles/s41467-024-46171-5
Title: Astronomy &amp; Planetary Science Thread
Post by: Star One on 03/14/2024 08:19 am
Betelgeuse’s boiling surface ‘mimics’ rotation in animation:

https://youtu.be/0-8_qf3BCl8?si=Axm2c783HEEr71Pv
Title: Re: Astronomy & Planetary Science Thread
Post by: Star One on 03/15/2024 08:39 am
Quote
Astronomers report the discovery of a new warm Jupiter exoplanet orbiting a distant star in the open cluster Messier 67. The newfound extrasolar world, designated S1429 b, is almost twice as massive as Jupiter. The finding was detailed in a paper published March 5 on the pre-print server arXiv.



Quote
According to the paper, S1429 b has a minimum mass of 1.8 Jupiter masses and orbits its host star every 77.48 days on a most likely circular orbit, at a distance of approximately 0.384 AU from it. The equilibrium temperature of the planet was estimated to be about 683 K.

https://phys.org/news/2024-03-jupiter-exoplanet-orbiting-distant-star.html

Related paper:

https://arxiv.org/abs/2403.02911