CH₄ and CO₂ (& (CH₃)₂S ?) found in atmosphere of habitable-zone exoplanet

[Occam's Banana]

CH₄ and CO₂ (& (CH₃)₂S ?) found in atmosphere of habitable-zone exoplanet

Methane and carbon dioxide found in atmosphere of habitable-zone exoplanet
https://www.cam.ac.uk/stories/carbon-found-in-habitable-zone-exoplanet
Sarah Collins | 11 September 2023

An international team of astronomers led by the University of Cambridge has used data from the NASA/ESA/CSA James Webb Space Telescope to discover methane [CH[SUB]4[/SUB]] and carbon dioxide [CO[SUB]2[/SUB]] in the atmosphere of K2-18 b, an exoplanet in the ‘Goldilocks zone’. This is the first time that carbon-based molecules have been discovered in the atmosphere of an exoplanet in the habitable zone.

The results are consistent with an ocean-covered surface underneath a hydrogen-rich atmosphere. The discovery provides a glimpse into a planet unlike anything else in our Solar System, and raises interesting prospects about potentially habitable worlds elsewhere in the Universe.

K2-18 b — which is 8.6 times as massive as Earth — orbits the cool dwarf star K2-18 in the habitable zone and lies 110 light years from Earth in the constellation of Leo. A first insight into the atmosphere of K2-18 b came from observations with the Hubble Space Telescope but the atmospheric composition has been a subject of debate. The same researchers studied K2-18 b in 2020 and 2021, and identified it as belonging to a new class of habitable exoplanets called ‘Hycean’ worlds which could accelerate the search for life elsewhere. This prompted them to take a more detailed look with JWST, Hubble’s successor.

Using JWST’s higher resolution instruments, this new investigation has definitively identified methane and carbon dioxide in a hydrogen-rich atmosphere on K2-18 b.

The researchers also identified another, weaker, signal in the K2-18 b spectrum. After several analyses, the researchers say that the signal could be caused by a molecule called dimethyl sulphide (DMS) [(CH[SUB]3[/SUB])[SUB]2[/SUB]S]. On Earth, DMS is only produced by life, primarily microbial life such as marine phytoplankton, suggesting the possibility of biological activity on K2-18 b. While these signs of DMS are tentative and require further validation, the researchers say that K2-18 b and other Hycean planets could be our best chance to find life outside our Solar System.

The results, which have been accepted for publication in The Astrophysical Journal Letters, will be presented today (11 September) at the First Year of JWST Science Conference in Baltimore, Maryland, USA.

 

[Brian4Liberty]

Methane and carbon dioxide found in atmosphere of habitable-zone exoplanet

Carbon dioxide?! OMG, humans have already ruined the atmosphere. Methane and carbon dioxide are bad. This dead planet should be a lesson to us, when humans and cows create too much CO2 and methane.

 

[Occam's Banana]

Carbon dioxide?! OMG, humans have already ruined the atmosphere. Methane and carbon dioxide are bad. This dead planet should be a lesson to us, when humans and cows create too much CO2 and methane.

Clearly, "climate change" is a much larger and more widespread problem than anyone thought.

I guess we're gonna need some bigger grants and subsidies ...

 

[Brian4Liberty]

Clearly, "climate change" is a much larger and more widespread problem than anyone thought.

I guess we're gonna need some bigger grants and subsidies ...

The planet may be habitable, as long as they have bugs to eat.

 

[TheTexan]

I call dibs on new planet

 

[Brian4Liberty]

I call dibs on new planet

I already have one.

 

[Occam's Banana]

Did JWST find a MARKER OF LIFE in an exoplanet atmosphere?
https://www.youtube.com/watch?v=F360SGAlI8Y
{Dr. Becky | 21 September 2023}

There’s been a big claim of a marker of life, known as a biosignature, found using JWST in the atmosphere of an exoplanet known as K2-18b. The data also confirmed this planet was a “Hycean” world, a planet with a liquid water ocean surrounded by a hydrogen dominated atmosphere. The biosignature that’s claimed to have been found is dimethyl sulphide, a molecule that on Earth is mostly produced by phytoplankton in the ocean. But how strong actually is the evidence for this claimed detection of dimethyl sulphide?

Madhusudhan et al (2023; JWST observations of K2-18b) - https://arxiv.org/pdf/2309.05566.pdf
Bell et al. (2023; JWST methane detection in the atmosphere of WASP-80b) - https://arxiv.org/pdf/2309.04042.pdf
Benneke et al. (2019; HST observations of K2-18b and detection of water) - https://arxiv.org/pdf/1909.04642.pdf
Hu et al. (2021; prediction of the molecules present in a hycean world atmosphere) - https://arxiv.org/pdf/2108.04745.pdf
Greaves et al. (2021; phosphine detected in Venus’ atmosphere) - https://arxiv.org/pdf/2009.06593.pdf
Constantinou et al. (2023; the different JWST reduction pipelines for exoplanet data) - https://arxiv.org/pdf/2301.02564.pdf
Seager et al. (2013; biosignatures in exoplanet atmospheres) - https://arxiv.org/pdf/1309.6016.pdf

JWST proposal 2722 - https://www.stsci.edu/jwst/phase2-public/2722.pdf
JWST proposal 2372 - https://www.stsci.edu/jwst/phase2-public/2372.pdf

Dr Jake Taylor on Twitter: https://twitter.com/astrojake
Dr Jake Taylor on TikTok: https://www.tiktok.com/@astrojaket
Dr Ryan MacDonald on Twitter: https://twitter.com/MartianColonist
Prof Jayne Birkby on Twitter: https://twitter.com/jaynebirkby

00:00 Introduction
01:24 What do we already know about K2-18b?
04:01 How we use JWST to study exoplanet atmospheres
06:00 What has JWST found in the atmosphere of K2-18b
12:17 The caveats to these results (especially the DMS claim)
14:08 What’s next? How can we confirm or deny this claim of DMS?
15:52 Bloopers

Correction: 02:38 K2-18b is LESS dense than Earth, not more dense. Verbal typo.