So far with TRAPPIST-1 planets on Fraser Cain's YouTube chanel. Detailed interview with a specialist, PhD candidate Megan Gialluca. Her enthusiasm is infectious. The vid's 73 minutes, so you might not have the spare time to watch it all. I'll summarize it as I watch it myself, updating this post along the way.
TL;DR: 'Bare rock' is the most likely - but not certain - explanation for b, more to come on c and the rest. There's still a lot more to discover and confirm, which will take time requiring repeated observations over years to come.
One big problem is 'stellar contamination.' TRAPPIST-1 is an active red dwarf and can have coverage of 30% in spots or faculae, so what could be interesting results in the light reflected off planets or possibly filtered through their (potential) atmospheres may in fact be the star just being weird.
At 27:00 there's a sum-up of the possible atmostpheres for b and c. b most likely has none, c could be somewhat hot Mars-like but with a thin O2-dominated atmosphere and a smidgen or CO2. O2 would not be indicative of life but the planets would have lost a lot of water and other volatiles in past ages and the O2 is a remnant of the water molecules split by stellar radiation. It would be a 'post-greenhouse' world (my term).
At 35:15 d is smaller that the roughly earth-mass b and c and consequently less likely to hold onto an atmosphere. Gialluca's quite excited by it though because it's on the inner boundary of the habitable zone - but is it just inside or just outside? Finding out will help us in understanding the HZ (or HZs, as there are different definitions).
40:00 e, f, g, h - far, far too soon to tell. Apparently something 'exciting' - to an astronomer - may be published soon on e. Then she talks about upcoming observation cycles with JWST.
At 43:30 an explanation of what stellar contamination is. At 53:00 the star actually flares ~3.6 times per day, which is a LOT - ten times what was predicted from Kepler 2 mission.
About 1:00:00, cunning means of mitigating contamination. Then why it's so exciting to be working on this, at this time.
At 1:05:20 notes on life detection and biosignatures - there are going to be a lot of false positives and ambiguous results, so temper your enthusiasm when you see the news of a possible detection. This leads to discussion about the impotance of good science communication and also learning to live with uncertainty.
BTW, she mentions 'HWO' - that's the Habitable Worlds Observatory, a follow-on to JWST. We glimpse some concepts for that at 1:10:15 just before the end and a reminder that you can see more about it on Patreon.
View: https://www.youtube.com/watch?v=B8H4EnbKkgU&t=3s&ab_channel=FraserCain
arxiv.org
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