The nature of sub-Neptunes is one of the hottest topics in exoplanetary science.

Temperate sub-Neptunes are of special interest because some could be #habitable.

But these #planets might instead be rocky worlds with thick, hot atmospheres.

#astronomy #exoplanets
https://astrobiology.com/2025/04/deciphering-sub-neptune-atmospheres-new-insights-from-geochemical-models-of-toi-270-d.html

Astronomers have detected the most promising signs yet of a possible #biosignature outside the solar system, although they remain cautious.

They have detected the chemical fingerprints of dimethyl sulfide and/or dimethyl disulfide, in the #atmosphere of the #exoplanet K2-18b, which orbits its star in the #habitable zone.

On Earth, theyare only produced by #life, primarily microbial life such as marine phytoplankton.

#astronomy #astrobiology
https://www.cam.ac.uk/stories/strongest-hints-of-biological-activity

Proxima Centauri is our nearest stellar neighbor and is known to be a very active M dwarf #star.

Known to host a potentially #habitable #planet, the star #Proxima exhibits very active #flare activity in optical wavelengths.

Depending on the energy and frequency of these flares, nearby planets in the habitable zone might be rendered uninhabitable as the flares strip planetary atmospheres of necessary ingredients such as ozone and water.

#astronomy #astrobiology
https://phys.org/news/2025-03-small-star-mighty-flares-alma.html

For decades, scientists have debated how small #exoplanets form.

New model suggests that #planets form in narrow rings at specific locations in the #protoplanetary disk, making #planet formation more organized than previously believed.

Simulations also imply that up to about 1% of super-Earth and mini-Neptune systems could host Earth-like planets within the #habitable zone.

This implies an occurrence rate of approximately one Earth-like planet per 300 sun-like stars.

https://astrobiology.com/2025/03/research-on-super-earths-and-mini-neptunes-suggests-more-earth-like-planets-may-exist.html

Astronomers have detected a super-Earth orbiting GJ 3998, a nearby red dwarf located 59 light years away.

The new #planet, named GJ 3998 d, is the third planet found in the system and has a mass 6 times larger than that of the Earth.

It resides in the optimistic #habitable zone of its star and completes an orbit once every 41.8 days.

At this distance, GJ 3998 d gets just 20% more stellar insolation compared to what Earth receives by the Sun.

#exoplanets #astronomy
https://astrobiology.com/2025/03/a-super-earth-discovered-in-the-habitable-zone-of-nearby-red-dwarf-gj-3998.html

"Fröhliche Wissenschaft: Das Brettspiel „Habitable“ basiert auf Erkenntnissen aus der Astronomie. Es zeigt, wie man Ergebnisse der Wissenschaft spielerisch vermitteln kann" @tazgetroete: https://taz.de/!6063881/
Online spielen: https://tabletopia.com/games/habitable
Weiterführende infos: https://www.h-its.org/de/2023/10/25/habitable-online/
#Wissenschaft #Spielen #Astronomie #Habitable #Wissenschaftskommunikation #SciComm

The circumstellar liquid-water #habitable zone guides the search for inhabited #exoplanets, but remains observationally untested.

The inner edge of the habitable zone can be mapped among exoplanets using their lack of surface #water, which, unlike the presence of water, can be unambiguously revealed by atmospheric sulfur species.

A population-level search for sulfur-chemistry on M-dwarf #planets can be used to empirically define the habitable zone.

#astrobiology
https://astrobiology.com/2025/01/tracing-the-inner-edge-of-the-habitable-zone-with-sulfur-chemistry.html

The organic material found in a few areas on the surface of dwarf #planet #Ceres is probably of exogenic origin.

Impacting asteroids from the outer asteroid belt may have brought it with them.

Instead, the dwarf planet's #cryovolcanism, in which salty brine rises from the body's interior to the surface, is not responsible for the organic deposits.

These findings help to understand where and how #habitable conditions could have arisen in the solar system.

#astrobiology
https://phys.org/news/2025-01-dwarf-planet-ceres-material-space.html

Calendrier de l' #avent de l' #exobiologie (17/24)

Qu'est-ce que la zone #habitable autour d'une étoile ?
C'est la plage de distance autour d'une étoile pour laquelle on peut en théorie concevoir la présence d'eau liquide à la surface d'une (exo)planète. C'est une affaire de distance à l'étoile...

Warm rocky #exoplanets within the #habitable zone of Sun-like stars are favoured targets for current and future missions.

Theory indicates these #planets could be wet at formation and remain habitable long enough for life to develop.

Synthetic observations reliably point to Earth-like #biosphere surface fluxes of oxygen for systems within 10-20 parsecs.

#astrobiology
https://astrobiology.com/2024/12/detectability-of-biosignatures-in-warm-water-rich-atmospheres.html

Paper by Taysum et al. (2024):
https://arxiv.org/abs/2412.01266

The history of #water on early #Mars is uncertain.

Determining when water first appeared, where and for how long, are all burning questions that drive Mars exploration. If Mars was once #habitable, some amount of water was required.

Studying the mineral zircon in a #meteorite from Mars reveaös evidence that water was present when the zircon crystal formed 4.45 billion years ago.

These new results may represent the oldest evidence for water on Mars.

#astrobiology
https://theconversation.com/a-4-45-billion-year-old-crystal-from-mars-reveals-the-planet-had-water-from-the-beginning-243172

Most of the #exoplanets we've discovered orbit red dwarf #stars.

This is because about 75% of the stars in the Milky Way are red dwarfs, so you would expect red dwarf planets to be the most abundant.

This also means that most #habitable worlds are going to orbit these small, cool stars, and that has some significant consequences for our search for #life.

But even detecting the atmospheres of such planets may be extremely difficult in practice.

#astronomy #astrobiology
https://phys.org/news/2024-09-exoplanets-atmospheres.html

#space #mars #habitable

Ancient Rocks in Mars' Jezero Crater Confirm Habitability.
https://www.universetoday.com/168134/ancient-rocks-in-mars-jezero-crater-confirm-habitability/ via @universetoday

Fast-Tracking the Search for #Habitable #Worlds

https://www.universetoday.com/168015/fast-tracking-the-search-for-habitable-worlds/
#space #universe #astronomy @nasa

The #habitable zone #exoplanet LHS 1140 b is unlikely to be a mini-Neptune, a small gas #planet with a thick hydrogen-rich atmosphere.

The planet is less dense than rocky planets with an Earth-like composition, suggesting that 10 to 20% of its mass may be composed of #water.

It is a candidate water world, likely resembling a snowball or ice planet with a potential liquid ocean at the sub-stellar point.

https://phys.org/news/2024-07-astronomers-ice-world-habitable-zone.html

Paper by Cadieux et al. (2024):
https://arxiv.org/abs/2406.15136

The# sun warms the Earth, making it #habitable for people and animals.

But that's not all it does, and it affects a much larger area of #space. The #heliosphere, the area of space influenced by the sun, is over a hundred times larger than the distance from the sun to the Earth.

Earth's atmosphere protects life on the planet from the effects of cosmic radiation, but the heliosphere itself acts as a cosmic shield from most interstellar radiation.

#astronomy
https://phys.org/news/2024-06-nasa-interstellar-probe-heliosphere-region.html