Author Topic: Exoplanet Thread  (Read 10165 times)

Offline Star One

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Exoplanet Thread
« 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

Offline Star One

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Exoplanet Thread
« Reply #1 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
« Last Edit: 01/26/2017 06:57 PM by Star One »

Offline ikke666

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Re: Exoplanet Thread
« Reply #2 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,...)

Offline testguy

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Re: Exoplanet Thread
« Reply #3 on: 01/27/2017 05:29 PM »
Try this.  Updates daily.

http://exoplanet.eu/catalog/

Online hop

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Re: Exoplanet Thread
« Reply #4 on: 01/28/2017 06:00 AM »
There's also the NASA Exoplanet archive http://exoplanetarchive.ipac.caltech.edu/

Offline Star One

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Re: Exoplanet Thread
« Reply #5 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/

Offline ikke666

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Re: Exoplanet Thread
« Reply #6 on: 01/28/2017 03:55 PM »
thanks for the sites  ;D

Offline Star One

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Re: Exoplanet Thread
« Reply #7 on: 02/02/2017 08:38 PM »

Offline Star One

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Re: Exoplanet Thread
« Reply #8 on: 02/13/2017 07:36 PM »
Quote
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#

Offline Star One

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Exoplanet Thread
« Reply #9 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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« Last Edit: 02/15/2017 08:05 PM by Star One »

Offline Mongo62

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Re: Exoplanet Thread
« Reply #10 on: 02/28/2017 07:23 PM »
Towards Detection of Exoplanetary Rings Via Transit Photometry: Methodology and a Possible Candidate

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.

Offline Star One

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Exoplanet Thread
« Reply #11 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
« Last Edit: 03/10/2017 06:51 PM by Star One »

Offline jebbo

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Re: Exoplanet Thread
« Reply #12 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

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

Online Bynaus

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Re: Exoplanet Thread
« Reply #13 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.

Offline jebbo

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Re: Exoplanet Thread
« Reply #14 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
« Last Edit: 03/13/2017 05:50 PM by jebbo »

Offline Star One

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Re: Exoplanet Thread
« Reply #15 on: 03/13/2017 08:10 PM »
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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

Offline Star One

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Exoplanet Thread
« Reply #16 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
« Last Edit: 03/14/2017 01:48 PM by Star One »

Offline Star One

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Re: Exoplanet Thread
« Reply #17 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

Online Bynaus

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Re: Exoplanet Thread
« Reply #18 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.

Offline Star One

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Re: Exoplanet Thread
« Reply #19 on: 03/28/2017 08:17 PM »

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #20 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⊕.

Offline Star One

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Re: Exoplanet Thread
« Reply #21 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/

Offline Star One

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Exoplanet Thread
« Reply #22 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
« Last Edit: 04/06/2017 08:37 PM by Star One »

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #23 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



Interesting 3:2 orbital resonances between planets b and c, c and d, and d and e.

Offline jebbo

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Re: Exoplanet Thread
« Reply #24 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
« Last Edit: 04/09/2017 04:49 PM by jebbo »

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #25 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)

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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.

Online Bynaus

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Re: Exoplanet Thread
« Reply #26 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)

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.
« Last Edit: 04/18/2017 06:54 AM by Bynaus »

Offline Star One

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Re: Exoplanet Thread
« Reply #27 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

Offline Star One

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Re: Exoplanet Thread
« Reply #28 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/

Offline Star One

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Re: Exoplanet Thread
« Reply #29 on: 04/26/2017 06:52 PM »
Speculations on Habitable Zone Waterworlds

Quote
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

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #30 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! :)

Offline Star One

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Re: Exoplanet Thread
« Reply #31 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.

Offline Star One

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Re: Exoplanet Thread
« Reply #32 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/

Offline Star One

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Re: Exoplanet Thread
« Reply #33 on: 04/28/2017 07:10 PM »
Planetary Discovery around Ultracool Star

Quote
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

Offline Star One

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Exoplanet Thread
« Reply #34 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
« Last Edit: 05/03/2017 05:37 PM by Star One »

Offline Star One

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Re: Exoplanet Thread
« Reply #35 on: 05/10/2017 08:46 PM »
Exploring the Planet / Brown Dwarf Boundary

http://www.centauri-dreams.org/?p=37665

Offline missinglink

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Re: Exoplanet Thread
« Reply #36 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

Offline gospacex

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Re: Exoplanet Thread
« Reply #37 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...

Offline Star One

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Re: Exoplanet Thread
« Reply #38 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.

Offline Torbjorn Larsson, OM

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Re: Exoplanet Thread
« Reply #39 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."

Offline missinglink

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Re: Exoplanet Thread
« Reply #40 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.
« Last Edit: 05/11/2017 08:36 PM by missinglink »

Offline dror

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Re: Exoplanet Thread
« Reply #41 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.
"If we crave some cosmic purpose, then let us find ourselves a worthy goal. "
Carl Sagan, Pale Blue Dot

Offline Star One

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Re: Exoplanet Thread
« Reply #42 on: 05/11/2017 09:19 PM »
NASA Study Finds Unexpectedly Primitive Atmosphere Around ‘Warm Neptune’

Quote
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

Offline missinglink

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Re: Exoplanet Thread
« Reply #43 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.

Offline gospacex

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Re: Exoplanet Thread
« Reply #44 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!
« Last Edit: 05/12/2017 05:50 PM by gospacex »

Offline Oli

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Re: Exoplanet Thread
« Reply #45 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.

Offline TakeOff

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Re: Exoplanet Thread
« Reply #46 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.

Offline TakeOff

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Re: Exoplanet Thread
« Reply #47 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.

Online hop

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Re: Exoplanet Thread
« Reply #48 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

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #49 on: 05/16/2017 08:30 PM »
K2-106, a system containing a metal rich planet and a planet of lower density (arXiv)

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!

Offline Star One

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Re: Exoplanet Thread
« Reply #50 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

Offline Star One

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Re: Exoplanet Thread
« Reply #51 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/

Offline Star One

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Exoplanet Thread
« Reply #52 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
« Last Edit: 05/30/2017 11:33 AM by Star One »

Online hop

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Re: Exoplanet Thread
« Reply #53 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 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.

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #54 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!

Offline Star One

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Re: Exoplanet Thread
« Reply #55 on: 06/02/2017 07:14 PM »
Citizen scientists uncover a cold new world near sun

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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

Offline Star One

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Exoplanet Thread
« Reply #56 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.
« Last Edit: 06/05/2017 04:19 PM by Star One »

Offline Star One

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Re: Exoplanet Thread
« Reply #57 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

Offline Star One

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Re: Exoplanet Thread
« Reply #58 on: 06/09/2017 04:51 PM »
 Planet Formation around TRAPPIST-1

https://www.centauri-dreams.org/?p=37917

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #59 on: 06/13/2017 02:44 AM »
Two new massive planets detected around the star HD 27894 (Phys.org article).
Three planets around HD 27894 (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.

Offline Star One

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Exoplanet Thread
« Reply #60 on: 06/13/2017 08:24 AM »
I still can't help wonder if there are more planets in the large gap.
« Last Edit: 06/13/2017 08:31 AM by Star One »

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Re: Exoplanet Thread
« Reply #61 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).
« Last Edit: 06/13/2017 08:37 AM by Bynaus »

Offline Star One

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Re: Exoplanet Thread
« Reply #62 on: 06/13/2017 08:35 PM »
New evidence that all stars are born in pairs

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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/

Offline Star One

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Re: Exoplanet Thread
« Reply #63 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

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #64 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.)

Offline clongton

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Re: Exoplanet Thread
« Reply #65 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.
« Last Edit: 06/16/2017 12:22 AM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

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Re: Exoplanet Thread
« Reply #66 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

Offline Alpha_Centauri

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Re: Exoplanet Thread
« Reply #67 on: 06/19/2017 10:22 AM »
Sounds like it is just announcing the search rather than any discoveries yet.

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Re: Exoplanet Thread
« Reply #68 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
« Last Edit: 06/19/2017 10:42 AM by jebbo »

Offline Star One

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Exoplanet Thread
« Reply #69 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.
« Last Edit: 06/19/2017 10:50 AM by Star One »

Offline Alpha_Centauri

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Re: Exoplanet Thread
« Reply #70 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.
« Last Edit: 06/19/2017 11:03 AM by Alpha_Centauri »

Offline jebbo

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Re: Exoplanet Thread
« Reply #71 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

Offline Star One

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Exoplanet Thread
« Reply #72 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?
« Last Edit: 06/19/2017 11:44 AM by Star One »

Offline jebbo

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Re: Exoplanet Thread
« Reply #73 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

Offline Star One

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Exoplanet Thread
« Reply #74 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?
« Last Edit: 06/19/2017 12:02 PM by Star One »

Offline jebbo

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Re: Exoplanet Thread
« Reply #75 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
« Last Edit: 06/19/2017 12:27 PM by jebbo »

Offline Star One

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Re: Exoplanet Thread
« Reply #76 on: 06/19/2017 08:34 PM »
Article on the same.

Pale Red Dot: Campaign 2

https://www.centauri-dreams.org/?p=37964

Offline CuddlyRocket

Re: Exoplanet Thread
« Reply #77 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.

Offline jebbo

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Re: Exoplanet Thread
« Reply #78 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, and predates the latest DR25 release.

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

--- Tony




Offline Alpha_Centauri

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Re: Exoplanet Thread
« Reply #79 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).
« Last Edit: 06/20/2017 11:17 AM by Alpha_Centauri »

Offline jebbo

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Re: Exoplanet Thread
« Reply #80 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

Offline Alpha_Centauri

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Re: Exoplanet Thread
« Reply #81 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
« Last Edit: 06/20/2017 12:52 PM by Alpha_Centauri »

Offline Star One

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Exoplanet Thread
« Reply #82 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.
« Last Edit: 06/20/2017 07:22 PM by Star One »

Offline Star One

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Re: Exoplanet Thread
« Reply #83 on: 06/23/2017 08:52 PM »

Offline Star One

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Exoplanet Thread
« Reply #84 on: Today at 10:56 AM »
Betelgeuse captured by ALMA

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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.
« Last Edit: Today at 10:57 AM by Star One »

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