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Flyaway

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FighterJock

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Flyaway

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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.
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?
 

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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.
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?

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.
 

Flyaway

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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
 

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


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.
 

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


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.
NASA has you already covered on that.

 

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


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.
NASA has you already covered on that.


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?
 

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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
 

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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?

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!
 

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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?

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!

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.
 

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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.
Better than a participation trophy. There's an impact crater with signs of past liquid water:


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.

 

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Evidence that Ultra-high-energy Gamma Rays Are a Universal Feature near Powerful Pulsars

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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.


Source: https://phys.org/news/2021-04-ultra-high-energy-gamma-rays-pulsar-nebulae.html
 

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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."

 

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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.


Source: https://phys.org/news/2021-04-chinese-astronomers-black-hole-x-ray.html
 

Flyaway

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

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

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

More about this proposed mission on the link below.

 

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

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

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

More about this proposed mission on the link below.


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/
 

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


 

Flyaway

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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.

 
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