Does exoplanet K2-18b host alien life or not? Here's why the debate continues

[Admin]

A paper published in 2023 spurred discussion about whether life exists on an exoplanet named K2-18b. Two years later, the puzzle continues — and some scientists are expressing doubt.

Does exoplanet K2-18b host alien life or not? Here's why the debate continues : Read more

 

[rod]

Glad to see some more reporting on K2-18b. Here are some past reports attempting to sort out if the exoplanet has life on it or not

Webb discovers methane, carbon dioxide in atmosphere of K2-18 b, https://phys.org/news/2023-09-webb-methane-carbon-dioxide-atmosphere.html

Exoplanet's surface may be covered in oceans, James Webb Space Telescope finds, https://forums.space.com/threads/ex...ceans-james-webb-space-telescope-finds.63084/

Is K2-18b covered in oceans of water or oceans of lava?, https://phys.org/news/2024-01-k2-18b-oceans-lava.html

Another explanation for K2-18b? A gas-rich mini-Neptune with no habitable surface, https://phys.org/news/2024-01-explanation-k2-18b-gas-rich.html

JWST data suggest exoplanet K2-18b may have molten surface rather than a watery ocean, https://phys.org/news/2024-02-jwst-exoplanet-k2-18b-molten.html

 

[Helio]

It's hard to get that optimistic about this exoplanet, IMO, when we are looking at an exoplanet that is only 0.14 AU from an M2.5V (cool) red dwarf, and is on the warm side of the normal HZ (0.97 sol. equivalent AU). Red dwarfs are fully convective and known for violent flares, though perhaps this planet's atmosphere makes it protective enough.

Also, this exoplanet is large, about 9x the mass of Earth. This may, or may not, be an issue as it is at the border of what many think is an upper limit in size, at least for intelligent life. Too early to say, of course.

K2-18 b
HZ locations	6% / 5%
Sol. Eq. Dist., AU	0.97
a, AU	0.14
Radius (E)	2.32
Dist., pc.	38.1
Surf. g (E)	1.7
Vesc (E)	2.0
Type	M2.5 V

 

[rod]

Helio et al. Barnard's star now has 4 small exoplanets confirmed

Confirmed at Last: Barnard’s Star Hosts Four Tiny Planets

Following decades of disproven claims, four small exoplanets have been confirmed to orbit Barnard’s Star, the second-closest star system.

skyandtelescope.org

Four tiny planets are orbiting one of our nearest stars

Astronomers have revealed new evidence that not just one, but four tiny planets are circling around Barnard's Star, the second-nearest star system to Earth.

phys.org

 

[Helio]

That's nice to hear! I suspect none are in the HZ for that system, however.

Exoplanet.eu only lists Barnard b so far, though it likely has the others in their unconfirmed list for now. [At those short periods, it won't take many weeks to confirm them.]

Oddly, their website (exoplanet.eu) has deleted the mass and radius values for over 1000 exoplanets. But they still show the error values for each of those. I had to write a program to use their older stated values in hopes this is a hiccup in their programing, and not that the prior values were way off.

BTW, this includes Proxima, which is the closest as this article notes. Strange!

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