Exoplanet's surface may be covered in oceans, James Webb Space Telescope finds

The space.com article does call attention to something important about K2-18 b. "Is this proof of life outside the solar system? In addition to turning up carbon molecules, the JWST findings also showed the possible presence of something potentially more exciting in the atmosphere of K2–18 b. The space telescope seems to have detected dimethyl sulfide (DMS), which on Earth is only produced as a by-product of life, mainly created by phytoplankton. The team is cautious about this detection, which is far less certain than the presence of carbon molecules. "Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2–18 b at significant levels," explained Madhusudhan. This sense of caution has to be applied to the K2–18 b findings in general when it comes to speculating about alien life. Even if the planet has a liquid water ocean and an atmosphere containing carbon molecules, that doesn't necessarily mean it harbors life or that the exoplanet could even support living things at all. With a width of around 2.6 times that of Earth, the planet's size means its interior contains high-pressure ice similar to Neptune but with a thinner atmosphere and an ocean surface. This means the planet may be boiling away liquid water, making its oceans too hot to host life."

I note here from the 22-page PDF on this exoplanet. ref - Carbon-bearing Molecules in a Possible Hycean Atmosphere, https://esawebb.org/media/archives/releases/sciencepapers/weic2321/weic2321a.pdf, 11-Sep-2023. “ABSTRACT The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science...." “1. INTRODUCTION The detection and characterisation of habitable-zone exoplanets is a major frontier in modern astronomy. Until recently, the quest for exoplanetary habitability and biosignatures have been focused primarily on rocky exoplanets, naturally motivated by the terrestrial experience of life (Kasting et al. 1993; Meadows & Barnes 2018). The extreme diversity of exoplanetary systems witnessed over the past three decades motivates considerations of new avenues in the search for life elsewhere."

My note, given the mass and radius published for K2-18 b, the surface gravity is 1.5879E+00 or almost 1.6 g where on Earth we have 1.0 g. Without Charles Darwin desire for a general law of nature that shows how life evolves from non-living matter as he expressed in his letter of 28-Feb-1882 established among the laws of nature, on what basis do we extrapolate the origin of life developing from non-living matter on hycean worlds? Abiogenesis would need to be very flexible and fall under a general law of nature I would think.

From the 22-page PDF report. "4.3. Possible Evidence of Life Our potential evidence for DMS in K2-18 b motivates consideration of possible biological activity on the planet. While the present evidence is not as strong as that for CH4 or CO2, upcoming JWST observations of K2-18 b will be able to robustly constrain the presence and abundance of DMS, as discussed in section 4.5 and earlier work (Madhusudhan et al. 2021). Here we discuss the plausibility of our DMS abundance constraints from a potential biosphere on K2-18 b in order to inform future observations and retrieval studies."
 
Aug 17, 2023
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Two very important caveats here: 1. The detection of dimethyl sulphide, which is indicative of simple lifeforms such as phytoplankton, was very preliminary and must be confirmed on subsequent observations. 2. Due to the stupendous nature of the discovery of alien life, the JWST cannot confirm this discovery by itself (due to previously established protocols) and it must be verified by another source to corroborate its certainty.
 
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Harmonograms, I would think your points 1 and 2 are needed very much for such reporting, especially to the public. We have 5510 exoplanets confirmed at this site, http://exoplanet.eu/, and 5514 exoplanets at the NASA archive site, https://exoplanetarchive.ipac.caltech.edu/index.html

This space.com report and some others today (Webb discovers methane, carbon dioxide in atmosphere of K2-18 b, https://phys.org/news/2023-09-webb-methane-carbon-dioxide-atmosphere.html), is the first I read where alien life could be claimed living on an exoplanet. I remember reports of phosphine in Venus's atmosphere, Martian meteorite ALH84001, and other reports of life on Mars. Example, NASA may have unknowingly found and killed alien life on Mars 50 years ago, scientist claims, https://forums.space.com/threads/na...-on-mars-50-years-ago-scientist-claims.63068/
 
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There are other likely problematic circumstances:
1) It orbits is at 0.14 AU, so it probably is in a tidal lock.
2) It orbits an M2.5 class star, which are becoming more and more known to be stars that throw tantrums (CMEs, flares, etc.)
3) It's also in the hotter portion of the HZ using the stellar class method for luminosity or for the temperature method (star temp.)
4) It is about 20% farther beyond the HZ zone closer to the star, thus too hot for liquid water, based on the Kopparapu et. al. method (atmospherics).