Author Topic: Astronomy & Planetary Science Thread  (Read 441963 times)

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1600 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

Online DanClemmensen

  • Senior Member
  • *****
  • Posts: 5484
  • Earth (currently)
  • Liked: 4316
  • Likes Given: 1758
Re: Astronomy & Planetary Science Thread
« Reply #1601 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.

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1602 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

Offline Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 15287
  • Liked: 7823
  • Likes Given: 2
Re: Astronomy & Planetary Science Thread
« Reply #1603 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.

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1604 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.

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1605 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

Online Comga

  • Senior Member
  • *****
  • Posts: 6466
  • Liked: 4572
  • Likes Given: 5136
Re: Astronomy & Planetary Science Thread
« Reply #1606 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
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!
« Last Edit: 03/25/2023 08:04 pm by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online DanClemmensen

  • Senior Member
  • *****
  • Posts: 5484
  • Earth (currently)
  • Liked: 4316
  • Likes Given: 1758
Re: Astronomy & Planetary Science Thread
« Reply #1607 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
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.

Offline deadman1204

  • Full Member
  • ****
  • Posts: 1782
  • USA
  • Liked: 1468
  • Likes Given: 2520
Re: Astronomy & Planetary Science Thread
« Reply #1608 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
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

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1609 on: 03/28/2023 11:02 pm »
Space scientists reveal brightest gamma explosion ever https://www.bbc.co.uk/news/uk-england-leicestershire-65104115

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1610 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#

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Astronomy &amp; Planetary Science Thread
« Reply #1611 on: 03/30/2023 05:27 pm »
Largest black hole found yet revealed through gravitational lensing:



An astonishing 30 billion solar masses.
« Last Edit: 03/30/2023 06:28 pm by Star One »

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1612 on: 04/02/2023 07:37 pm »
‘Unique’ black hole that’s only 3800 light-years away discovered by Gaia:


Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1613 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#

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1614 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

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1615 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#

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1616 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

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1617 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:


Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1618 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:


Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy & Planetary Science Thread
« Reply #1619 on: 04/13/2023 07:25 pm »
First-ever black hole image ‘sharpened’ using machine learning:


 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1