#ETHZ:
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Exoplaneten sind keine Wasserwelten
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"An der Oberfläche von fernen Planeten ausserhalb unseres Sonnensystems gibt es viel weniger Wasser als bisher vermutet. Diese Exoplaneten haben keine dicken Wasserschichten, wie oft spekuliert wurde. Das zeigt eine internationale Studie unter Leitung der ETH Zürich."
https://ethz.ch/de/news-und-veranstaltungen/eth-news/news/2025/09/exoplaneten-sind-keine-wasserwelten.html
18.9.2025
#Astronomie #Atmosphäre #Chemie #Exoplanet #HyceanPlanet #JWST #Planetologie #SubNeptun #Wasser #Wasserstoff #Wasserwelt
Exoplaneten sind keine Wasserwelten
An der Oberfläche von fernen Planeten ausserhalb unseres Sonnensystems gibt es viel weniger Wasser als bisher vermutet. Diese Exoplaneten haben keine dicken Wasserschichten, wie oft spekuliert wurde. Das zeigt eine internationale Studie unter Leitung der ETH Zürich.
Biomoleküle auf fernem Exoplaneten entdeckt
Die Atmosphäre einer fernen Welt enthält zwei von irdischen Mikroben hergestellte Schwefelverbindungen. Sie könnten auf biologische Aktivität hindeuten.
in the #arXiv
On the Ocean Conditions of Hycean Worlds
by Frances Rigby and Nikku Madhusudhan
https://arxiv.org/abs/2402.12330
📷 Artist depiction, by @pablocarlosbudassi, of a hycean planet - a hypothetical type of planet with a hydrogen atmosphere and a surface ocean that can potentially support life.
#hycean #planets #exoplanets #exoplanet #planet #hyceanplanet #hyceanplanets #life #water #ocean #oceans #hydrogen #studies #models #physics #astronomy #astrodon #science #STEM #Cambridge_Uni
On the Ocean Conditions of Hycean Worlds
Recent studies have suggested the possibility of Hycean worlds, characterised by deep liquid water oceans beneath H$_2$-rich atmospheres. These planets significantly widen the range of planetary properties over which habitable conditions could exist. We conduct internal structure modelling of Hycean worlds to investigate the range of interior compositions, ocean depths and atmospheric mass fractions possible. Our investigation explicitly considers habitable oceans, where the surface conditions are limited to those that can support potential life. The ocean depths depend on the surface gravity and temperature, confirming previous studies, and span 10s to $\sim$1000 km for Hycean conditions, reaching ocean base pressures up to $\sim$6$\times$10$^4$ bar before transitioning to high-pressure ice. We explore in detail test cases of five Hycean candidates, placing constraints on their possible ocean depths and interior compositions based on their bulk properties. We report limits on their atmospheric mass fractions admissible for Hycean conditions, as well as those allowed for other possible interior compositions. For the Hycean conditions considered, across these candidates we find the admissible mass fractions of the H/He envelopes to be $\lesssim$10$^{-3}$. At the other extreme, the maximum H/He mass fractions allowed for these planets can be up to $\sim$4-8$\%$, representing purely rocky interiors with no H$_2$O layer. These results highlight the diverse conditions possible among these planets and demonstrate their potential to host habitable conditions under vastly different circumstances to the Earth. Upcoming JWST observations of candidate Hycean worlds will allow for improved constraints on the nature of their atmospheres and interiors.
RTN
Daniel Pomarède