Next up, we‘ve got Kazumasa Ohno on the hazy sub-Neptune GJ1214 b.

Previous observations show pretty flat lines, likely due to hazes and clouds. The JWST phase curve with MIRI shows a large amplitude indicative of high metallicity, but the spectrum is still consistent with a flat line. It is though predicted to have CO2 and CH4 features so they observed with #G395H. And??? 🧐 #ExSSV

They looked at the c planet which is favourable with #NIRISS and find methane and hazes. Intriguingly, they don‘t find any O-bearing species. We know that water is hard to see when methane is present. But CO2 should be observable if present! Hmmm? What‘s going on?

It could be trapped in silicates in the interior. #ExSSV

Next up, we‘ve got Pierre-Alexis Roy on #JWST observations of LP791-18c revealing an atmosphere abundant methane and depleted CO2.

Already with #HST, advances were made to observe sub-Neptunes, but without much luck except for the coldest ones. #JWST has brought us a long way already though the SNR for K2-18 b is not high enough, but TOI-270 d proved better and rewrote the rules.

But what‘s in between: LP 791-18 is a system with 3 planets around an M dwarf. #ExSSV

The atm of TOI-270 d is heavy, but they don‘t find ammonia. Their GCMs reveal a well-mixed super-critical vapour envelope.

For colder planets, the story looks a bit different: more layers are added ranging from the coldest Hycean worlds to stratified mini-Neptunes.

Caroline shows us the spectrum of GJ 9827 d, dominated by water.

As of now, we reached the state that we can observe/measure the mean molecular weight + temperature transitions, where CH4 is favoured over CO. #ExSSV

The bare rock case is not possible, but for the other two they performed 3D GCMs analyses. They produced transmission spectra and find that observations should be able to discriminate between the scenarios if we can deal with stellar contamination.

#JWST comes into play with 4 transits, but I am not allowed to share it with you 🚫🤫 #ExSSV

P.S.: I realised that the speaker has actually changed. It is Charles Cadieux.

Next up, we’ve got René Doyon on LHS 1140 b: a mini-Neptune or water world? 🧐

There are two planets in this system: one super-Earth and the other one… we don‘t know?

It is located in a regime where it is likely to have an atmosphere. The planet has been observed with plenty of instruments, which they reanalysed. For planet c, this results in agreement but for b this suggests three scenarios:

Mini-neptune with rocky core + H/He envelope, water world or a bare rock? #ExSSV

Rapid rotators have a saturated flare rate, while slow rotators have very low flare rates.

Transition pairs are mostly ordered by mass. The active pairs are kinematically you g, while inactive pairs are kinematically old.

Let‘s link this to star formation: it comes in two epochs. Until ~9 Gyr ago we were forming thick disc stars and now we are forming thin disc stars.

Terrestrial are common, Jovians are not. #ExSSV