Astronomy and Planetary Science Thread

FighterJock said:
Flyaway said:
Article:

findplanetnine.blogspot.com

The Inner Oort Cloud Connection

The census of Kuiper belt objects spanning the distant solar system has sure come a long way. Even if we strictly limit our object sample to...
findplanetnine.blogspot.com findplanetnine.blogspot.com

Paper:

Click to expand...

An interesting article Flyaway. There is an awful lot that we do not know about the hidden reaches of the outer solar system, and whether planet nine is real or not.
Click to expand...
Did you see a few years ago that there was a paper proposing that early in its life that like many stars of its type the Sun had a stellar companion. But this was ejected from the Sun by gravitational interactions in the stellar nursery?
 
Flyaway said:
FighterJock said:
Flyaway said:
Article:

findplanetnine.blogspot.com

The Inner Oort Cloud Connection

The census of Kuiper belt objects spanning the distant solar system has sure come a long way. Even if we strictly limit our object sample to...
findplanetnine.blogspot.com findplanetnine.blogspot.com

Paper:

Click to expand...

An interesting article Flyaway. There is an awful lot that we do not know about the hidden reaches of the outer solar system, and whether planet nine is real or not.
Click to expand...
Did you see a few years ago that there was a paper proposing that early in its life that like many stars of its type the Sun had a stellar companion. But this was ejected from the Sun by gravitational interactions in the stellar nursery?
Click to expand...

Our Sun is an oddball in the Milky Way having no Stellar companion, I remember reading about that paper online, it also reignited the whole Nemesis debate years before the planet nine was ever mentioned as a possibility.
 
Discovery of a directly imaged planet to the young solar analog YSES 2

Abstract
Context. To understand the origin and formation pathway of wide-orbit gas giant planets, it is necessary to expand the limited sample of these objects. The mass of exoplanets derived with spectrophotometry, however, varies strongly as a function of the age of the system and the mass of the primary star.
Aims. By selecting stars with similar ages and masses, the Young Suns Exoplanet Survey (YSES) aims to detect and characterize planetary-mass companions to solar-type host stars in the Scorpius-Centaurus association.
Methods. Our survey is carried out with VLT/SPHERE with short exposure sequences on the order of 5 min per star per filter. The subtraction of the stellar point spread function (PSF) is based on reference star differential imaging using the other targets (with similar colors and magnitudes) in the survey in combination with principal component analysis. Two astrometric epochs that are separated by more than one year are used to confirm co-moving companions by proper motion analysis.
Results. We report the discovery of YSES 2b, a co-moving, planetary-mass companion to the K1 star YSES 2 (TYC 8984-2245-1, 2MASS J11275535-6626046). The primary has a Gaia EDR3 distance of 110 pc, and we derive a revised mass of 1.1 M⊙ and an age of approximately 14 Myr. We detect the companion in two observing epochs southwest of the star at a position angle of 205° and with a separation of ~1.′′05, which translates to a minimum physical separation of 115 au at the distance of the system. Photometric measurements in the H and Ks bands are indicative of a late L spectral type, similar to the innermost planets around HR 8799. We derive a photometric planet mass of 6.3−0.9+1.6 MJup using AMES-COND and AMES-dusty evolutionary models; this mass corresponds to a mass ratio of q = (0.5 ± 0.1)% with the primary. This is the lowest mass ratio of a direct imaging planet around a solar-type star to date. We discuss potential formation mechanisms and find that the current position of the planet is compatible with formation by disk gravitational instability, but its mass is lower than expected from numerical simulations. Formation via core accretion must have occurred closer to the star, yet we do not find evidence that supports the required outward migration, such as via scattering off another undiscovered companion in the system. We can exclude additional companions with masses greater than 13 MJup in the full field of view of the detector (0.′′15<ρ<5.′′50), at 0.′′5 we can rule out further objects that are more massive than 6 MJup, and for projected separations ρ >2′′ we are sensitive to planets with masses as low as 2 MJup.
Conclusions. YSES 2b is an ideal target for follow-up observations to further the understanding of the physical and chemical formation mechanisms of wide-orbit Jovian planets. The YSES strategy of short snapshot observations (≤5 min) and PSF subtraction based on a large reference library proves to be extremely efficient and should be considered for future direct imaging surveys.


Source: https://phys.org/news/2021-04-giant-planet-large-distance-sun-like.html
 
Flyaway said:

Saturn Probe Data Reveal Impressive Depth of Titan’s Largest Sea​

www.scientificamerican.com

Saturn Probe Data Reveal Impressive Depth of Titan's Largest Sea

The moon’s massive pool of methane, ethane and nitrogen could potentially swallow skyscrapers
www.scientificamerican.com www.scientificamerican.com
Click to expand...

Interesting find Flyaway, I want to see another mission to Saturn before the next decade starts focusing on Titan, especially the large sea. Cassini left us a whole lot of unanswered questions when its mission was ended.
 
FighterJock said:
Flyaway said:

Saturn Probe Data Reveal Impressive Depth of Titan’s Largest Sea​

www.scientificamerican.com

Saturn Probe Data Reveal Impressive Depth of Titan's Largest Sea

The moon’s massive pool of methane, ethane and nitrogen could potentially swallow skyscrapers
www.scientificamerican.com www.scientificamerican.com
Click to expand...

Interesting find Flyaway, I want to see another mission to Saturn before the next decade starts focusing on Titan, especially the large sea. Cassini left us a whole lot of unanswered questions when its mission was ended.
Click to expand...
NASA has you already covered on that.

www.nasa.gov

NASA's Dragonfly Will Fly Around Titan Looking for Origins, Signs of Life - NASA

NASA has announced that our next destination in the solar system is the unique, richly organic world Titan. Advancing our search for the building blocks of
www.nasa.gov www.nasa.gov
 
Flyaway said:
FighterJock said:
Flyaway said:

Saturn Probe Data Reveal Impressive Depth of Titan’s Largest Sea​

www.scientificamerican.com

Saturn Probe Data Reveal Impressive Depth of Titan's Largest Sea

The moon’s massive pool of methane, ethane and nitrogen could potentially swallow skyscrapers
www.scientificamerican.com www.scientificamerican.com
Click to expand...

Interesting find Flyaway, I want to see another mission to Saturn before the next decade starts focusing on Titan, especially the large sea. Cassini left us a whole lot of unanswered questions when its mission was ended.
Click to expand...
NASA has you already covered on that.

www.nasa.gov

NASA's Dragonfly Will Fly Around Titan Looking for Origins, Signs of Life - NASA

NASA has announced that our next destination in the solar system is the unique, richly organic world Titan. Advancing our search for the building blocks of
www.nasa.gov www.nasa.gov
Click to expand...

Thanks Flyaway, But I am surprised that Dragon fly is going to be launched in 2026 and with arrival at Titan in 2034, That means that it will take eight years for Dragonfly to get to Titan. Why will it take so long for Dragonfly to get to Titan when Cassini only took seven years?
 
Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through Far-ultraviolet Observations

Abstract
We present the discovery of an extreme flaring event from Proxima Cen by the Australian Square Kilometre Array Pathfinder (ASKAP), Atacama Large Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST), Transiting Exoplanet Survey Satellite (TESS), and the du Pont Telescope that occurred on 2019 May 1. In the millimeter and FUV, this flare is the brightest ever detected, brightening by a factor of >1000 and >14,000 as seen by ALMA and HST, respectively. The millimeter and FUV continuum emission trace each other closely during the flare, suggesting that millimeter emission could serve as a proxy for FUV emission from stellar flares and become a powerful new tool to constrain the high-energy radiation environment of exoplanets. Surprisingly, optical emission associated with the event peaks at a much lower level with a time delay. The initial burst has an extremely short duration, lasting for <10 s. Taken together with the growing sample of millimeter M dwarf flares, this event suggests that millimeter emission is actually common during stellar flares and often originates from short burst-like events.


Source: https://phys.org/news/2021-04-humungous-flare-sun-nearest-neighbor.html
 
FighterJock said:

Thanks Flyaway, But I am surprised that Dragon fly is going to be launched in 2026 and with arrival at Titan in 2034, That means that it will take eight years for Dragonfly to get to Titan. Why will it take so long for Dragonfly to get to Titan when Cassini only took seven years?
Click to expand...

Cassini was able to take advantage of Earth, Venus and Jupiter flybys. Dragonfly isn't so lucky. Also, Titan's north pole will be in winter when it arrives, so it'll be dark. Dragonfly is therefore aiming for an equatorial landing site. A pity, since I'd love to see images of the shores of Ligeia!
 
Rhinocrates said:
FighterJock said:

Thanks Flyaway, But I am surprised that Dragon fly is going to be launched in 2026 and with arrival at Titan in 2034, That means that it will take eight years for Dragonfly to get to Titan. Why will it take so long for Dragonfly to get to Titan when Cassini only took seven years?
Click to expand...

Cassini was able to take advantage of Earth, Venus and Jupiter flybys. Dragonfly isn't so lucky. Also, Titan's north pole will be in winter when it arrives, so it'll be dark. Dragonfly is therefore aiming for an equatorial landing site. A pity, since I'd love to see images of the shores of Ligeia!
Click to expand...

A shame that the northern hemisphere of Titan will be in Winter. I hope that the equator will be a better alternative in terms of potential scientific points of interest.
 
FighterJock said:

A shame that the northern hemisphere of Titan will be in Winter. I hope that the equator will be a better alternative in terms of potential scientific points of interest.
Click to expand...
Better than a participation trophy. There's an impact crater with signs of past liquid water:

www.nasa.gov

NASA's Dragonfly Will Fly Around Titan Looking for Origins, Signs of Life - NASA

NASA has announced that our next destination in the solar system is the unique, richly organic world Titan. Advancing our search for the building blocks of
www.nasa.gov www.nasa.gov

A further proposed mission is a submarine, but it would be handy to know more about the nature of the seas first - the wave height seems to be weirdly low and there might be a floating layer of viscous material.

www.nasa.gov

Titan Submarine: Exploring the Depths of Kraken - NASA

Titan Submarine is unique in the outer solar system in that it is the only one of the bodies outside the Earth with liquid lakes and seas on its surface.
www.nasa.gov www.nasa.gov
 
Evidence that Ultra-high-energy Gamma Rays Are a Universal Feature near Powerful Pulsars

Abstract
The highest-energy known gamma-ray sources are all located within 0fdg5 of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; >56 TeV) gamma-ray emission is a universal feature expected near pulsars with a high spin-down power. Using four years of data from the High Altitude Water Cherenkov Gamma-Ray Observatory, we present a joint-likelihood analysis of 10 extremely powerful pulsars to search for subthreshold UHE gamma-ray emission correlated with these locations. We report a significant detection (>3σ), indicating that UHE gamma-ray emission is a generic feature of powerful pulsars. We discuss the emission mechanisms of the gamma rays and the implications of this result. The individual environment, such as the magnetic field and particle density in the surrounding area, appears to play a role in the amount of emission.

ShieldSquare Captcha

iopscience.iop.org iopscience.iop.org

Source: https://phys.org/news/2021-04-ultra-high-energy-gamma-rays-pulsar-nebulae.html
 
An international team of researchers searched for pieces of a small asteroid tracked in space and then observed to impact Botswana on June 2, 2018. Guided by SETI Institute meteor astronomer Peter Jenniskens, they found 23 meteorites deep inside the Central Kalahari Game Reserve and now have published their findings online in the journal Meteoritics and Planetary Science.

"Combining the observations of the small asteroid in space with information gleaned from the meteorites shows it likely came from Vesta, second largest asteroid in our solar system and target of NASA's DAWN mission," said Jenniskens. "Billions of years ago, two giant impacts on Vesta created a family of larger, more dangerous asteroids. The newly recovered meteorites gave us a clue on when those impacts might have happened."
Click to expand...

phys.org

Asteroid that hit Botswana in 2018 likely came from Vesta

An international team of researchers searched for pieces of a small asteroid tracked in space and then observed to impact Botswana on June 2, 2018. Guided by SETI Institute meteor astronomer Peter Jenniskens, they found 23 meteorites deep inside the Central Kalahari Game Reserve and now have...
phys.org phys.org
 
Optical and Ultraviolet Monitoring of the Black Hole X-ray Binary MAXI J1820+070/ASASSN-18ey for 18 Months

MAXI J1820+070 is a low-mass black hole X-ray binary system with high luminosity in both optical and X-ray bands during the outburst periods. We present extensive photometry in X-ray, ultraviolet, and optical bands, as well as densely-cadenced optical spectra, covering the phase from the beginning of optical outburst to ∼550 days. During the rebrightening process, the optical emission preceded the X-ray by 20.80 ± 2.85 days. The spectra are characterized by blue continua and emission features of Balmer series, He I, He II lines and broad Bowen blend. The pseudo equivalent width (pEW) of emission lines are found to show anticorrelations with the X-ray flux measured at comparable phases, which is due to the increased suppression by the optical continuum. At around the X-ray peak, the full width at half maximums (FWHMs) of Hβ and He II λ4686 tend to stabilize at 19.4 Angstrom and 21.8 Angstrom, which corresponds to the line forming region at a radius of 1.7 and 1.3 R_sun within the disk. We further analyzed the absolute fluxes of the lines and found that the fluxes of Hβ and He II λ4686 show positive correlations with the X-ray flux, favoring that the irradiation model is responsible for the optical emission. However, the fact that X-ray emission experiences a dramatic flux drop at t∼200 days after the outburst, while the optical flux only shows little variations suggests that additional energy such as viscous energy may contribute to the optical radiation in addition to the X-ray irradiation.

[2104.10370] Optical and Ultraviolet Monitoring of the Black Hole X-ray Binary MAXI J1820+070/ASASSN-18ey for 18 Months

arxiv.org

Source: https://phys.org/news/2021-04-chinese-astronomers-black-hole-x-ray.html
 
Why the renewed focus on astrometry when it comes to Alpha Centauri (a theme we saw as well in the previous post on ALMA observations from the surface)? One problem we face with other detection methods is simply statistical: We can study planets, as via the Kepler mission, by their transits, but if we want to know about specific stars that are near us, we can’t assume a lucky alignment.

Radial velocity requires no transits, but has yet to be pushed to the level of detecting Earth-mass planets at habitable-zone distances from stars like our own. This is why imaging is now very much in the mix, as is astrometry, and getting the latter into space in a dedicated mission has occupied a team at the University of Sydney led by Peter Tuthill for a number of years — I remember hearing Tuthill describe the technology at Breakthrough Discuss in 2016.

Out of this effort we get a concept called TOLIMAN, a space telescope that draws its title from Alpha Centauri B, whose medieval name in Arabic, so I’m told, was al-Zulmn. [Addendum: This is mistaken, as reader Joy Sutton notes in the comments. It wouldn’t be until well after the medieval period — in 1689 — that the binary nature of Centauri A and B was discovered by Jesuit missionary and astronomer Jean Richaud. The name al-Zulmn seems to be associated with an asterism that included Alpha Centauri, though I haven’t been able to track down anything more about it. Will do some further digging.]
Click to expand...

More about this proposed mission on the link below.

TOLIMAN: Looking for Earth Mass Planets at Alpha Centauri | Centauri Dreams

www.centauri-dreams.org
 
Flyaway said:
Why the renewed focus on astrometry when it comes to Alpha Centauri (a theme we saw as well in the previous post on ALMA observations from the surface)? One problem we face with other detection methods is simply statistical: We can study planets, as via the Kepler mission, by their transits, but if we want to know about specific stars that are near us, we can’t assume a lucky alignment.

Radial velocity requires no transits, but has yet to be pushed to the level of detecting Earth-mass planets at habitable-zone distances from stars like our own. This is why imaging is now very much in the mix, as is astrometry, and getting the latter into space in a dedicated mission has occupied a team at the University of Sydney led by Peter Tuthill for a number of years — I remember hearing Tuthill describe the technology at Breakthrough Discuss in 2016.

Out of this effort we get a concept called TOLIMAN, a space telescope that draws its title from Alpha Centauri B, whose medieval name in Arabic, so I’m told, was al-Zulmn. [Addendum: This is mistaken, as reader Joy Sutton notes in the comments. It wouldn’t be until well after the medieval period — in 1689 — that the binary nature of Centauri A and B was discovered by Jesuit missionary and astronomer Jean Richaud. The name al-Zulmn seems to be associated with an asterism that included Alpha Centauri, though I haven’t been able to track down anything more about it. Will do some further digging.]
Click to expand...

More about this proposed mission on the link below.

TOLIMAN: Looking for Earth Mass Planets at Alpha Centauri | Centauri Dreams

www.centauri-dreams.org
Click to expand...

I know that this is a bit late in getting posted but there maybe a spanner in the works in thinking there might life on the Earth like planet that has been discovered orbiting Proxima Centauri.

https://astronomynow.com/2021/04/21...a-centauri-dwarfs-any-ever-seen-from-the-sun/
 

'Oddball supernova' reveals star's death throes before exploding​


edition.cnn.com

'Oddball supernova' reveals star's death throes before exploding | CNN

For years, scientists have tried to determine what happens to massive stars just before they explode. Now, an unusual supernova is causing astronomers to redefine "what's physically possible" when stars go supernova.
edition.cnn.com edition.cnn.com
 
Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b

Recent discoveries of young exoplanets within their natal disks offer exciting opportunities to study ongoing planet formation. In particular, a planet's mass accretion rate can be constrained by observing the accretion-induced excess emission. So far, planetary accretion is only probed by the Hα line, which is then converted to a total accretion luminosity using correlations derived for stars. However, the majority of the accretion luminosity is expected to emerge from hydrogen continuum emission, and is best measured in the ultraviolet (UV). In this paper, we present HST/WFC3/UVIS F336W (UV) and F656N (Hα) high-contrast imaging observations of PDS 70. Applying a suite of novel observational techniques, we detect the planet PDS 70 b with signal-to-noise ratios of 5.3 and 7.8 in the F336W and F656N bands, respectively. This is the first time that an exoplanet has been directly imaged in the UV. Our observed Hα flux of PDS 70 b is higher by 3.5σ than the most recent published result. However, the light curve retrieved from our observations does not support greater than 30% variability in the planet's Hα emission in six epochs over a five-month timescale. We estimate a mass accretion rate of 1.4±0.2×10−8MJup/yr. Hα accounts for 36% of the total accretion luminosity. Such a high proportion of energy released in line emission suggests efficient production of Hα emission in planetary accretion, and motivates using the Hα band for searches of accreting planets. These results demonstrate HST/WFC3/UVIS's excellent high-contrast imaging performance and highlight its potential for planet formation studies.

[2104.13934] Hubble Space Telescope UV and H$α$ Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b

arxiv.org
 
Atomic-scale mixing between MgO and H2O in the deep interiors of water-rich planets

Abstract
Water-rich planets exist in our Solar System (Uranus and Neptune) and are found to be common in the extrasolar systems (some of the sub-Neptunes). In conventional models of these planets a thick water-rich layer is underlain by a separate rocky interior. Here we report experimental results on two rock-forming minerals, olivine ((Mg,Fe)2SiO4) and ferropericlase ((Mg,Fe)O), in water at the pressure and temperature conditions expected for the water-rich planets. Our data indicate a selective leaching of MgO, which peaks between 20 and 40 GPa and above 1,500 K. For water-rich planets with 1–6 Earth masses (>50 wt% H2O), the chemical reaction at the deep water–rock interface would lead to high concentrations of MgO in the H2O layer. For Uranus and Neptune, the top ~3% of the H2O layer would have a large storage capacity for MgO. If an early dynamic process enables the rock–H2O reaction, the topmost H2O layer may be rich in MgO, possibly affecting the thermal history of the planet.

www.nature.com

Atomic-scale mixing between MgO and H2O in the deep interiors of water-rich planets - Nature Astronomy

Under the pressure of a watery ocean, rock-forming minerals might dissolve at a planet’s rock–water interface, generating a denser-than-water layer that should be incorporated into models. The experimental data for MgO presented here are relevant to water-rich Earth-sized planets such as...
www.nature.com www.nature.com
 
Grey Havoc said:
Via Slashdot:
www.space.com

Metals found in the atmospheres of comets in and beyond our solar system surprise scientists

Metal atoms have surprisingly been discovered in the frigid atmosphere of the first known interstellar comet to visit our solar system, a new study finds.
www.space.com www.space.com
Click to expand...
The two related papers:

www.nature.com

Iron and nickel atoms in cometary atmospheres even far from the Sun - Nature

High-resolution ultraviolet and optical spectra of a large sample of comets show that Fe i and Ni i lines are ubiquitous, even when the comets are far from the Sun.
www.nature.com www.nature.com

www.nature.com

Gaseous atomic nickel in the coma of interstellar comet 2I/Borisov - Nature

Atomic nickel vapour is found in the cold coma of the interstellar comet 2I/Borisov at a distance of 2.3 astronomical units, equivalent to an equilibrium temperature of 180 kelvin.
www.nature.com www.nature.com
 
Anomalous diffusion across a tera-Gauss magnetic field in accreting neutron stars

Abstract

When mass falls on the polar regions of a neutron star in a binary X-ray source system, it tends to spread out over the entire surface. A long-standing question in research on this problem is: will the mass be anchored on the magnetic field lines and drag the field with it or is there a special mechanism that allows the mass to slip through the magnetic field lines, leading to much less distortion? As the amount of mass falling on the neutron star can actually be comparable with the neutron star mass, the question of which alternative holds is very important. We suggest an efficient mechanism that will allow the mass to slip through the lines. The mechanism is based on a strong ideal Schwarzschild (Structure and Evolution of the Stars. Princeton University Press, 1958) instability. As the instability itself is ideal, it cannot directly force the mass to slip though the lines. However, it can create a cascade of eddies whose scale extends down to a resistive scale, at the same time mixing the field lines up without breaking them. On this scale the mass can cross the lines. This instability is efficient enough that it can produce a mass flow in the plasma without growing to a large amplitude but saturates at a small one. The instability determines the mass per flux distribution of the accumulated material on different lines so that the equilibrium is marginal to the instability on every line. This makes the equilibrium unique. Thus, as the extra mass on the neutron star grows, the state of the outer shell proceeds through a sequence of unique critically unstable equilibria. In an appendix, an attempt is made to track the critical equilibria over long times.


Source: https://www.sciencealert.com/this-c...hrough-a-neutron-star-s-insane-magnetic-field
 
Last edited:
www.cnet.com

Burst of solar flares unlike anything seen 'in years' could trigger bright auroras this week

A solar outburst could prompt a geomagnetic storm on Earth.
www.cnet.com www.cnet.com

https://twitter.com/x/status/1396747876529807361
View: https://twitter.com/CarolynKennett/status/1396747876529807361

Loving this video from NASA's SDO, the sun has woken from its slumber and at the weekend sunspot AR2824 sent out 2 large flares and 10 smaller ones, as they reach Earth on Wednesday there may be aurora. #astronomy #watchingthesun
Click to expand...
 

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