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#exoplanet

9 posts9 participants2 posts today
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Daniel Fischer

Thermal Emission and Confirmation of the Frigid White Dwarf #Exoplanet WD 1856+534b: arxiv.org/abs/2504.16982 -> Exoplanet discovered in 2020 has the coldest temperatures ever measured, scientists say: abcnews.go.com/Technology/exop

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arXiv.orgThermal Emission and Confirmation of the Frigid White Dwarf Exoplanet WD 1856+534bWe report the detection of thermal emission from and confirm the planetary nature of WD 1856+534b, the first transiting planet known to orbit a white dwarf star. Observations with JWST's Mid-Infrared Instrument (MIRI) reveal excess mid-infrared emission from the white dwarf, consistent with a closely-orbiting Jupiter-sized planet with a temperature of $186^{+6}_{-7}$ K. We attribute this excess flux to the known giant planet in the system, making it the coldest exoplanet from which light has ever been directly observed. These measurements constrain the planet's mass to no more than six times that of Jupiter, confirming its planetary nature and ruling out previously unexcluded low-mass brown dwarf scenarios. WD 1856+534b is now the first intact exoplanet confirmed within a white dwarf's "forbidden zone", a region where planets would have been engulfed during the star's red giant phase. Its presence provides direct evidence that planetary migration into close orbits, including the habitable zone, around white dwarfs is possible. With an age nearly twice that of the Solar System and a temperature akin to our own gas giants, WD 1856+534b demonstrates JWST's unprecedented ability to detect and characterize cold, mature exoplanets, opening new possibilities for imaging and characterizing these worlds in the solar neighborhood.
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HistoPol (#HP) 🏴 🇺🇸 🏴

@mina @admin @evelynefoerster

... may be #Habitable (have conditions favorable to life). Whether our definitions of #Planet can be applied to these newly found objects remains to be seen."

science.nasa.gov/solar-system/planets/what-is-a-planet/#h-the-new-definition-of-planet

s/: Ich mein', #ExoPLANET, wie schwierig kann da eine Klassifikation schon sein? /s 🤦‍♀️🤦‍♂️🤦

Im Übrigen muss ein #Planet auch nicht bewohnbar sein! --sonst hätte das #Solarsystem nur einen einzigen. Und überhaupt:...

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Six Grandfathers Mountain

@badibulgator @bigiain @scalzi
RE
#Mars is the third one which is (sometimes) easy to spot even from very light-polluted places

Sure, I see that slight red, pink small non-twinking Mars, sometimes. I know it takes 9 months to get there with current tech. That's a big event, like the time it takes to have a baby

I'm always amazed that some/many non scientific folks used to be on the fence in the past where #UFOs were a thing. ZERO chance to the nearest #exoplanet, about 300,000 yr travel time

Public
Daniel Fischer

"We show that numerous alternative models without potential biosignature gases provide equivalent or better fits to the observations" of #exoplanet K2-18 b by the JWST: "We demonstrate that the significance of a claimed detection relies on the choice of models being compared, and that model preference does not necessarily imply the presence of any specific gas." Says the new paper arxiv.org/abs/2504.21788 "The Challenges of Detecting Gases in Exoplanet Atmospheres" - d'oh ...

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arXiv.orgThe Challenges of Detecting Gases in Exoplanet AtmospheresClaims of detections of gases in exoplanet atmospheres often rely on comparisons between models including and excluding specific chemical species. However, the space of molecular combinations available for model construction is vast and highly degenerate. Only a limited subset of these combinations is typically explored for any given detection. As a result, apparent detections of trace gases risk being artifacts of incomplete modeling rather than robust identification of atmospheric constituents, especially in the low signal-to-noise regime. We illustrate these challenges using the sub-Neptune K2-18~b, where recent claims of a potential biosignature detection vanish when the considered model space is expanded. We show that numerous alternative models without potential biosignature gases provide equivalent or better fits to the observations. We demonstrate that the significance of a claimed detection relies on the choice of models being compared, and that model preference does not necessarily imply the presence of any specific gas.
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Val

Did We Detect Life on an Alien Planet? With David Kipping — StarTalk
iv.ggtyler.dev/watch?v=7wyNd8U

"Did we find life on a distant exoplanet? Neil deGrasse Tyson and astronomer David Kipping discuss the discovery of biosignatures found on K2-18b, how strong they are, and whether it means we found other life in the universe."

StarTalk | InvidiousDid We Detect Life on an Alien Planet? With David KippingGo to https://ground.news/startalk to stay fully informed on the latest Space and Science news. Save 40% off through our link for unlimited access to the Vantage plan this month. Did we find life on a distant exoplanet? Neil deGrasse Tyson and astronomer David Kipping discuss the discovery of biosignatures found on K2-18b, how strong they are, and whether it means we found other life in the universe. Timestamps: 00:00 - What's Up With K2-18b? 2:31 - Hycean Worlds & Detecting Biomarkers 4:12 - When Biomarkers Don’t Mean Life 7:09 - Could We Be Wrong? 10:10 - Getting More Data with JWST Check out our second channel, @StarTalkPlus Get the NEW StarTalk book, 'To Infinity and Beyond: A Journey of Cosmic Discovery' on Amazon: https://amzn.to/3PL0NFn Support us on Patreon: https://www.patreon.com/startalkradio FOLLOW or SUBSCRIBE to StarTalk: Twitter: http://twitter.com/startalkradio Facebook: https://www.facebook.com/StarTalk Instagram: https://www.instagram.com/startalk About StarTalk: Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up! #StarTalk #NeildeGrasseTyson
#Astronomy#Exoplanet#Astrobiology
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RiffReporter

Leben im #All? Forschende wollen auf dem #Exoplanet K2–18b mögliche Biomarker wie DMS entdeckt haben – ein Stoff, der auf der Erde nur von #Mikroben produziert wird. Ein „wimmelnder Ozean“ oder doch nur heiße Gesteinswelt? Christian J. Meier erklärt es: riffreporter.de/de/wissen/exop

Die Illustration zeigt, wie K2–18b aussehen könnte. Forscher haben Hinweise auf Leben auf diesem Exoplaneten gefunden. K2–18b hat die 8,6-fache Masse der Erde, umkreist seinen Stern in der sogenannten bewohnbaren Zone und ist 124 Lichtjahre von der Erde entfernt.
RiffReporter · Exoplanet K2–18b: Astronomen beobachten mögliche Spuren von außerirdischem LebenBy Dr. Christian J. Meier
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Michael Busch

Cool science. Not aliens.

QT Dr Ryan MacDonald @distantworlds.space‬
2025 April 23

Nice to see this research note on K2-18b from @astrojake.bsky.social , which demonstrates that a flat line (i.e. no spectral features) is a good fit to the MIRI data.

#exoplanet

arxiv.org/abs/2504.15916

bsky.app/profile/distantworlds

Bluesky Social · Dr Ryan MacDonald (@distantworlds.space)Nice to see this research note on K2-18b from @astrojake.bsky.social, which demonstrates that a flat line (i.e. no spectral features) is a good fit to the MIRI data. #exoplanet 🪐 🔭 arxiv.org/abs/2504.15916
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