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Hycean Planets Might Be Habitable Ocean Worlds
According to the researchers, Hycean worlds could greatly accelerate the search for life elsewhere. In some ways they are reminiscent of Earth, largely or even completely covered by oceans. Yet they are also uniquely alien: up to 2.6 times the diameter of Earth, with temperatures up to 200 degrees C (about 400 degrees F) and thick hydrogen atmospheres. This places them somewhere between Earth and giant planets like Neptune or Uranus.
[...] How, then, might Hycean planets be habitable? Having plentiful liquid water is of course a good start. These planets, unlike most mini-Neptunes, may have solid surfaces, like Earth. Many of the known Hycean candidates are larger and hotter than Earth, but still would be able to host large oceans, the researchers say. The conditions might be similar to some of the more extreme aquatic environments on our planet, but could theoretically still support at least microbial life.
[...] So, how would astronomers look for evidence of life on any of these worlds? They will search for biosignatures, chemical fingerprints of biological processes in the planets' atmospheres. Some common ones are oxygen, ozone, methane and nitrous oxide, as well as methyl chloride and dimethyl sulphide. The last two are not common on Earth, but might be on hydrogen-rich planets.
[...] Madhusudhan and his team say that many of these biosignatures should be easily detectable on Hycean planets. In fact, the nature of the planets themselves – larger sizes, higher temperatures and hydrogen-rich atmospheres – means that the biosignatures would be even more easily detectable than on Earth-like planets.
Also at ScienceAlert and Syfy Wire.
Journal Reference:
Nikku Madhusudhan, Anjali A. A. Piette, Savvas Constantinou. Habitability and Biosignatures of Hycean Worlds - IOPscience, The Astrophysical Journal (DOI: 10.3847/1538-4357/abfd9c, arXiv)
(Score: 2) by c0lo on Thursday September 02 2021, @03:30AM (4 children)
Reading TFSciAbstract, I got it. The guys say there could exist such planets sustaining a local life (to generate some oxygen that humans need for breathing) and having at least some zones where humans can live (assuming they are OK to float while doings so).
2.6 R⊕ at 10 M⊕ gets a wee under 1.5g at the surface.
A thicker atmosphere extends the distance to the outer limit of the Goldilocks zone - so higher chances to discover habitable conditions when looking for ocean worlds than when looking for smaller but denser rocky planets.
(fucking sci journos and their "translation")
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 3, Insightful) by takyon on Thursday September 02 2021, @04:04AM (2 children)
"Potentially habitable exoplanets" is understood to be a broad term, including plenty of planets that would be bad vacation spots for humans. Some of the candidates might be being blasted clean by red dwarf radiation. I don't think atmospheric oxygen is a required characteristic, just liquid water.
Interestingly, this list over here [wikipedia.org] already includes planets at up to 2.5 Earth radii (only up to 6.98 Earth masses, for LHS 1140 b [wikipedia.org], but the masses for the planets above 2 Earth radii are unknown or need to be updated).
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by c0lo on Thursday September 02 2021, @04:18AM
[Citation needed] to correct my understanding.
No seriously, I'll be grateful for one.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 2) by c0lo on Thursday September 02 2021, @04:43AM
Corrections to my understanding of the term [wikipedia.org]
* Life in general, not just human life.
* Life is not a requirement for habitability.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 2) by Freeman on Thursday September 02 2021, @01:47PM
Yet, the atmosphere could contain enough concentrations of something toxic to humans that it would be essentially uninhabitable.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"