bibianaprinoth, 2 months ago

We continue with Jackie Faherty on #methane #emission in a cold #exoworld with #JWST.

We start with a controversial topic: what is a planet? 🥹 Jackie works with #brown #dwarfs, and she asks us to pretend we talk about exoplanets 🤓

T and Y dwarfs are colder objects, basically Jupiters.

Jackie shows us a wonderful temperature sequence - or is it? Look at the carbon chaos! There is no sequence. Welcome to the BD mess ✨ #ExSSV

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bibianaprinoth, 2 months ago

Have a look at the methane chaos: there are two objects that are just … weird 😅 W1935 + W2220.

These two objects looked like clones of each other: similar ammonia, similar CO, similar CO2, buuuut… what is happening with methane?

It’s not absorption, but emission 🥸

So what can be the reason for emission in one but the other? #ExSSV

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bibianaprinoth, 2 months ago

Running #retrievals shall give us the answer. Let’s check the T-p profile:

There is a temperature inversion! Keep in mind: this is NOT a planet. There is no host star 🤯

Help? Solar system? Help?

Spoiler: they think it’s an aurora ✨

Largely bc of the sun the outer planets do have a temperature inversion, but there is a energy crisis. Io, Jupiter’s moon, is “heating” Jupiter.

Jackie is not saying there is a moon, but… she’s also not saying there isn’t. #JWST C4 time please? #ExSSV

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bibianaprinoth, 2 months ago

@PlanetaryGao begins his talk with a reminder that being nervous is okay 🫶

We’re looking at the super-puff Kepler-51 b 💨 A #super-puff is a planet that is a bit odd: similar mass to sub-Neptunes but larger radii.

How do we form these? How do we put so much atmosphere on it? One explanation: Forming beyond the snowline + subsequent migration.

Kepler-51 is an #extreme system. It hosts only super puffs around a solar-like star. Most of the oxygen is in water, most of the carbon is in methane.

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bibianaprinoth, 2 months ago

A flat spectrum appears. Why? Clouds ☁️ or rings 💍!

Let’s talk #clouds. These are the models. But… I cannot show you the data, so stay tuned for Masuda+ & Gao+🤗 #ExSSV

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bibianaprinoth, 2 months ago

We continue with Jonathan Fortney on GJ436 b - the original archetype #warm #Neptune

It has an intriguingly “large” eccentricity (I disagree that 0.14 is large sorry 🤓).

Thermal emission from the planet showed to be different for the #Spitzer points, at the time explained through atmospheric chemistry: non-equilibrium + mixing.

Reanalysis + follow-up showed a lower point at 3.6 micron, so less bright, but still brighter. Suggestion: tidal heating driving up the interior? #ExSSV

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bibianaprinoth, 2 months ago

The favoured explanation was a strong methane depletion due to tidal heating (hot interior) + vertical mixing. In the Spitzer era, this was the explanation, so they wanted to look at these kinds of planet with #JWST.

Plenty of visits with #JWST show a much much shallower 3.6 micron eclipse. While a must deeper at 4.5 micron (sorry I didn’t catch that plot).

So these observations with #JWST, agreeing with each other, but disagreeing with Spitzer. #ExSSV

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bibianaprinoth, 2 months ago

Atm, they are running retrievals to determine what is going on. This is still work in progress, so I won’t share.

Currently: no direct evidence for tidal heating, so stay tuned!! ✨ #ExSSV

bibianaprinoth, 2 months ago

Next up, we are going back to #direct #imaging!

Shrish Ray talks about the early release science of the direct imaging team of #JWST.

There are four sub-programs: exoplanets with coronagraphy, discs with coronagraphy, spectroscopy of exoplanets and aperture masking interferometry.

Imaging with #MIRI and #NIRCam clearly identify the planet.

Spectroscopy with #MIRI reveals water and methane and CO, as well as silicate clouds in VHS 1256-1257 b. #ExSSV

Blue: NIRCam, purple: MIRI.
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bibianaprinoth, 2 months ago

The disk imaging part is still in progress, so we’ll skip to aperture masking interferometry: this enables imaging below the diffraction limit.

This allows probing a new parameter space closer to the star.

This sounds great, but there are some problems 🫣 The contrast is ~1-2 mag shallower due to charge leaking between neighbouring pixels (bleeding charge). And this is something that needs to be addressed!! #ExSSV

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bibianaprinoth, 2 months ago

For the last talk in this session, we jump to TRAPPIST-1 f with #NIRISS by Olivia Lim.

Sadly, I am not allowed to share much here because this is still work in progress 🚫 but stay tuned!

But one thing I can say, from Olivia’s 2023 paper on TRAPPIST-1 b, is that stellar spots and faculae are making things hard.

#ExSSV

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bibianaprinoth, 2 months ago

That’s a wrap for our morning session. We’ll be back in the afternoon with transiting planets,
transit timing variations and more #JWST. #ExSSV