The JWST found the strongest possible life sign from exoplanet K2-18 b.

The exoplanet K2-18 b is a water world or the Hycean planet. Distance to that planet is about 124 light years. The ocean planet is the so-called sub-Neptune. That exoplanet orbits the red dwarf K2-18 in 33 days. The earth is quite far from its host star. But it's locked. And the surface temperature is about -5-+8C. When we think about the red dwarf eruption. The oceans can give protection against that radiation pike. 

The thing that makes the K-2-18b so interesting is that in its atmosphere are carbon dioxide, methane, and dimethyl sulfide. There is only a 0,3 percent possibility that those gasses form in some other ways than in biological processes. 

"In 2019, the presence of water vapour in K2-18b's atmosphere was reported, drawing scientific attention to this system. In 2023, the JWST detected carbon dioxide and methane in the atmosphere of K2-18b. JWST’s data has been variously interpreted as indicating a water ocean planet with a hydrogen-rich atmosphere, and a gas-rich mini-Neptune. K2-18b has been studied as a potential habitable world that, temperature aside, more closely resembles an ice giant like Uranus or Neptune than Earth." (Wikipedia, K2-18b)

"The graph shows the observed transmission spectrum of the habitable zone exoplanet K2-18 b using the JWST MIRI spectrograph. (A. Smith, N. Madhusudhan/University of Cambridge)" (ScienceAlert, Strongest Evidence of Alien Life Yet Found 124 Light-Years Away)

"In 2025, the atmosphere of K2-18b was found to contain dimethyl sulfide (DMS), a chemical that could serve as a biomarker on exoplanets in quantities 20 times higher than on Earth. As the molecule is short-lived, the concentration is highly suggestive that DMS is being replenished.[4] Other scientists criticised this statement and pointed to lab experiments that can produce DMS without life." (Wikipedia, K2-18b). 

The counter-criticism is that the DMS can be produced on purpose. But what is the possibility that the DMS forms in natural processes? 

So, the k2-18b is the best candidate for lifeforms. Those lifeforms can be very primitive, like some algae in our oceans. In this text, the "primitive" means that the lifeforms can look like something like fish. But it will not be technically advanced. 

We can think that K2-18b is like a very young Earth. 

There can be oxygen in its oceans. Even if. There is no oxygen in the atmosphere. 

The thing is that the K2-18b can have very complicated lifeforms like fish-type aliens. Those Hycean worlds are interesting. That means life itself can be quite a common thing in the universe. But the intelligent aliens might be rare things. 

https://www.livescience.com/space/exoplanets/james-webb-telescope-could-find-signs-of-life-on-alien-hycean-ocean-worlds

https://www.sciencealert.com/strongest-evidence-of-alien-life-yet-found-124-light-years-away

https://en.wikipedia.org/wiki/Hycean_planet

https://en.wikipedia.org/wiki/K2-18b

Can a binary star's planet host lifeforms?

"A strange new planet has been found circling two stars at a right angle — like something out of sci-fi. It’s the first solid evidence of a so-called polar orbit around a binary system. Credit: SciTechDaily.com" (ScitechDaily, Planet Found Orbiting Two Stars at a Perfect 90-Degree Angle)

The polar planet that orbits the binary star at a 90-degree angle can host life. There is only one of those polar exoplanets known. That planet orbits two brown dwarfs. So it will not host lifeforms. But it tells that the polar exoplanets exist. 

There is the possibility that if the planet orbits the binary star at a perfect 90-degree angle to the star's layer. That thing makes it possible that there are lifeforms on that planet. The binary stars are quite complicated things. And if the planet's orbital angle is perfect conditions on that planet can be stable. That can offer the harbor for life. 

The planet can also lie to the binary star. That means the binary star can be like any star. The planetary systems can form around the stars. Or the star can capture rogue planets around it. There is the model that the rogue planets are the most common planet types in the universe. Those planets can form in supernova remnants or when some cosmic shockwave travels through the small molecular clouds. 

"This is an artist’s impression of the exoplanet 2M1510 (AB) b’s unusual orbit around its host stars, a pair of brown dwarfs. The newly discovered planet has a polar orbit, which is perpendicular to the plane in which the two stars are traveling. Credit: ESO/L. Calçada" (ScitechDaily, Planet Found Orbiting Two Stars at a Perfect 90-Degree Angle)

"Using ESO’s Very Large Telescope (VLT), astronomers have found an exoplanet orbiting a pair of peculiar stars at an angle of 90 degrees. There have previously been hints that these so-called polar planets around two stars could exist, but we now have clear evidence that this is the case. This special system was found by observing the orbital path of the two stars being pushed and pulled in a way that could only be explained by the presence of a planet on a polar orbit. This video summarizes the discovery, explaining the nature of these peculiar stars and the method astronomers used to find this odd planet. Credit: ESO" (ScitechDaily, Planet Found Orbiting Two Stars at a Perfect 90-Degree Angle)

In that case, the planet axle is in the same direction as the binary star, so participants can orbit each other at close distance. 

Can act as the lone star. In that case. Those planets have night and day like on Earth. The other versions are so-called open or long-distance binary- or multiple stars. There is the possibility that both of those stars have their own planetary systems. Maybe those planets have not night at all. 

The binary star systems are more common than the lone star systems. In the 1990s most researchers thought that binary stars could not have planets because their gravity effect would destroy the protoplanet. 

Today we know. Also, binary stars have planets. The fact is that almost every red dwarf that we know has exoplanet systems. So, we can expand that model to other stars. That means that almost all stars should have planetary systems. Things like Barnard star's planetary systems tell us that the smallest red dwarfs can have multiple planets around them. Barnard's star is roughly larger than Jupiter's. And it has four planets.

https://scitechdaily.com/planet-found-orbiting-two-stars-at-a-perfect-90-degree-angle/

https://scitechdaily.com/a-century-old-cosmic-mystery-solved-four-hidden-planets-found-near-earth/