#KnowledgeBit: #Hycean #Planets are huge, hot worlds covered by oceans, with thick hydrogen atmospheres. They might be key to discovering life beyond Earth.
Although no Hycean worlds have been confirmed to exist, the massive exoplanet survey by NASA's Kepler mission identified several candidates.
Detections of carbon-bearing molecules in the atmosphere of a candidate #Hycean world, K2-18 b, with JWST are opening the prospects for characterising potential biospheres on temperate #exoplanets.
Hycean #planets are thought to be conducive for hosting microbial #life under conditions similar to those in the Earth’s oceans.
A large range of evolutionary rates and origination times are possible for unicellular life in oceanic environments.
#astrobiology #astronomy
https://astrobiology.com/2025/02/prospects-for-biological-evolution-on-hycean-worlds.html
#DidYouKnow: #Hycean #Planets are huge, hot worlds covered by oceans, with thick hydrogen atmospheres. They might be key to discovering life beyond Earth.
Although no Hycean worlds have been confirmed to exist, the massive exoplanet survey by NASA's Kepler mission identified several candidates.
Next up, we’ve got Nikku Madhusudhan on the #hycean #paradigm in the search for #life.
Our current observations are limited to mass/radius, so the interior structure is somewhat hidden from our knowledge. Their study of K2-18 b suggested that there is a possible scenario where water could be liquid on the surface: a Hycean world as a new regime for planetary habitability.
This was all theoretical so far; but they used #JWST to check it! #ExSSV
If #Hycean #Worlds Really Exist, What are Their #Oceans Like?
https://www.universetoday.com/165838/if-hycean-worlds-really-exist-what-are-their-oceans-like/
#Astronomers have been on the hunt for a new kind of #exoplanet in recent years – one especially suited for #habitability. They’re called hycean worlds, and they’re characterized by vast #liquidwater oceans and thick #hydrogen-rich #atmospheres.
Astronomers have been on the hunt for a new kind of exoplanet in recent years – one especially suited for habitability. They’re called hycean worlds, and they’re characterized by vast liquid water oceans and thick hydrogen-rich atmospheres. The name was coined in 2021 by Cambridge astronomer Nikku Madhusudhan, whose team got a close-up look at … Continue reading "If Hycean Worlds Really Exist, What are Their Oceans Like?"
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
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.
#DidYouKnow: #Hycean #Planets are huge, hot worlds covered by oceans, with thick hydrogen atmospheres. They might be key to discovering life beyond Earth.
Although no Hycean worlds have been confirmed to exist, the massive exoplanet survey by NASA's Kepler mission identified several candidates.
Recently, a mini-Neptune #exoplanet had its spectrum taken, revealing the presence of methane, carbon dioxide, hydrogen, and maybe dimethyl sulfide.
But the claims that have ensued, that it's a water-rich, #Hycean world with life in its atmosphere, are unsupported by the data.
It is vitally important that we do not fool ourselves by jumping to unsubstantiated conclusions. Unfortunately, almost everyone is still getting it wrong.
#astronony #astrobiology
https://bigthink.com/starts-with-a-bang/k2-18b-inhabited/
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