After some technical issued, we‘re back with Ryan MacDonald about the first #JWST spectrum of a white dwarf exoplanet.

I remember Ryan giving a talk with this title already at #ExSSV in NZ.

When our sun will die one day, Jupiter and Saturn may actually survive this catastrophic event. Sooo this is also something that could/should happen in other systems. Funnily only in recent years we started finding these left over planets around white dwarfs. #exoplanets5

Yeah you guessed it right. I am not allowed to share it with you 🚫🤫 Stay tuned! #ExSSV

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

We‘re back after lunch with David Charbonneau on the active lives of low mass stars.

First and foremost, not all M dwarfs are equal. The smallest ones allow us to study their planets.

They conducted a volume complete sample survey within 15 kpc. The goal: transit occurrence rates of terrestrial worlds, gas giants at the snowline and magnetic activity and active lifetimes.

The M dwarfs show two classes of slow + rapid rotators: something happens to them that makes them slow down #ExSSV.

@JuliaVSeidel High-res / SNR observations allow resolving sub-features! So instead of taking the whole transit now, we can also just take parts of it and resolve it in time. If you do that, you see that the sub feature comes from egress suggesting dynamics in the form of an equatorial jet. So what those ingress show us?

Does it confirm the jet, suggest radial winds or is it a global day to nightside wind? We‘ll friends, I am not allowed to share it with you. Stay tuned! 🤫🚫 #ExSSV

The high albedo on the west side suggests silicate clouds. ☁️ they form on the nightside and are advected towards the dayside and gradually evaporate. This is excellent work, omg!
#ExSSV

These observations cover both thermal emission and reflected light. Most of the flux is coming from the substellar point in the thermal emission regime, but as we go to shorter wavelengths, in the reflective regime, we see contributions from the west side: so the cloudier part with more reflective components.

The nightside is very low, this very cold. 🥶

In reflected light, there is an asymmetry where the light comes from, while the thermal emission is symmetric, and a rapid drop in T. #ExSSV

Next up, we‘ve got Louis-Philippe Coulombe talking a reflected light and thermal emission phase curve of an exo-Neptune.

Depending on the wavelength, we probe different chemistry, temperature, etc. regimes in the atmospheres of planets, see eg Jupiter. Often we need to observe at least twice or we just ignore reflected light, BUT #JWST can do both!

They looked at the full phase curve of the planet LTT 9779 b, sitting in the Neptune Desert. 🏜️

And here are the light curves!! #ExSSV

For forming planets, we‘ve got three components: Gas, volatiles, refractories. Jupiter only got the first two.

This brings us the ultra-hot Jupiter opportunity: our Jupiter is cloudy, while hot Jupiters let us glimpse into Jupiter-atmospheres and search for refractories and volatiles.

Using retrievals, they find that volatiles are super-solar, and the ice to rock ratio is super solar. So where did it form? Two scenarios are consistent, with enriched CO gas or solids #ExSSV

We‘re back with #atmospheres and #interiors, kicked off by Stefan Pelletier on a gas giant planet that formed with more ices than rocks.

Stefan reminds us that back in the days we did not think we would be able to understand the composition of stars, but here we are, studying planetary atmospheres. Though forming planets is more complex because so many mechanisms contribute to the end product.

Nowadays, we can point at Jupiter + study its composition, right? No, we only got volatiles! #ExSSV

For the last talk of this session, we‘ve got Ravi Kopparapu on the science of #technosignatures.

A technosignature is any element, molecule, feature,… that shows past or present life. Do we have the technology to detect technology?

We want to use atmospheric spectroscopy to detect biosignatures. What are technosignatures? An example is pollution through industrial activity (NO2) or CFCs or lights.

With enough telescope time, we‘d be able to see that! #ExSSV

Ligia dares us to take a leap of faith: don‘t go for the common (green) but dare to go for the rare (purple). I‘m sadly not allowed to share more, so stay tuned 🚫🤫 #ExSSV

The next talk is by Ligia Fonseca Coelho on colour as a tool to search for life in the cosmos - and why purple is the new green.

Detecting life? Ligia wishes good luck. Life is hard to predict: eg photosynthesis using light.

But Ligia tells us, photosynthesis also works in the dark, and instead makes use of heat. So for photosynthesis, we don‘t require light, but biological pigments. They are shining.

The problem? Microorganisms are competing and don‘t let anyone shine. #ExSSV

Here are the results for 1e and 1d. For 1d, water would be possible to detect after ~30 transits, but 1e needs a lot more transits…

The most promising case is T1e with an Archean CO2/methane diseq. biosignatures. So time will tell I guess 🤷🏼‍♀️ #ExSSV