AD |  To try everything Brilliant has to offer for free for a full 30 days, visit https://brilliant.org/DrBecky and you'll also get 20% off an annual premium subscription. | Back in 2023, we saw the first ever claim that JWST had discovered a possible signature of life in the atmosphere of an exoplanet, a planet orbiting another star in our galaxy the Milky Way. But the evidence for the claim that dimethyl sulphide exists in K218b’s atmosphere was weak. Now, in the past few months of 2024, we’ve had two new papers analysing the data from K218b which both claim there are other models that can explain K218b just as well, with the same level of statistical backing. So what is going on here? So let's dive into what’s going on so you can all make up your own mind.

Madhusudhan et al. (2023; hycean world with DMS evidence) https://arxiv.org/pdf/2309.05566.pdf
Shorttle et al. (2024; hydrogen atmosphere with magma ocean) https://arxiv.org/pdf/2401.05864
Wogan et al. (2024; miniNeptune) https://arxiv.org/pdf/2401.11082
Hu et al. (2021; prediction of the molecules present in a hycean world atmosphere) https://arxiv.org/pdf/2108.04745.pdf
Benneke et al. (2019; water vapour in K218b's atmosphere) https://arxiv.org/pdf/1909.04642.pdf
Cloutier et al. (2019; K218b mass) https://arxiv.org/pdf/1810.04731
ForemanMackey et al. (2015; K218b discovered in K2 data) https://arxiv.org/pdf/1502.04715
Seager et al. (2013; biosignatures in hydrogen atmospheres) https://arxiv.org/pdf/1309.6016.pdf

JWST proposal 2722 https://www.stsci.edu/jwst/phase2pub...
JWST proposal 2372 https://www.stsci.edu/jwst/phase2pub...

00:00 Introduction
02:45 What do we know about K218b so far?
05:21 Madhusudhan et al. (2023) K218b is a hydrogen atmosphere with a liquid water ocean with dimethyl sulphide
09:33 Shorttle et al. (2024) K218b has hydrogen atmosphere with a magma ocean
11:05 Wogan et al. (2024) K218b is just a miniNeptune
13:19 What data do we need to figure this out?
16:37 Bloopers

My previous video on K218b:    • Did JWST find a MARKER OF LIFE in an ...  
My previous video on the markers for life JWST is looking for:    • JWST is hunting for these FOUR signs ...  

Video filmed on a Sony ⍺7 IV



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‍ I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.


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