Even though the trends are a bit offset, the transit and eclipse spectroscopy samples show very consistent mass-metallicity slopes! Both are steeper than the Solar System trend - perhaps interesting... All this is also consistent with interior bulk metallicity inferences.

One of the highlights is the planet mass-(atmospheric) metallicity trend. While such a trend was somewhat controversial with HST measurements, this newer sample shows a much cleaner relationship. With ExoComp, we can break it down between O/H and C/H and compare directly to the Solar System.

There don't seem to be obvious trends or correlations between planet metallicity, C/O, temperature, stellar metallicity, or stellar mass. But carbon-dominated C/O > 1 planets appear to be rare, if any exist at all!

After we standardize the 65 atmosphere measurements from JWST and 8m-class telescopes, we can look for trends! And we see some surprises...

The first was that exoplanets measured by transit spectroscopy have low C/O compared to those measured in eclipse. It's not obvious why.

We've collected 65 individual exoplanet atmosphere composition measurements to look for population-level trends 🔭 #exoplanets

To do this, we had to create a toolkit to standardize between definitions of . We call it ExoComp. (Yes, that's a Star Trek reference 😀).

We find tentative evidence for a limb asymmetry in the huge NUV feature. 3D GCM models (with mag fields!) by @hayleybeltz.bsky.social to show that the data is (tentatively) more consistent with a model *with* a magnetic field than without!

More obs of, e.g., the hot spot offset, could help.

KELT-20b is unique compared to other UHJs in that it appears to be well-aligned with the rotation of its host star, perhaps indicating something unique about its formation.

Our measurements suggest the accretion of volatile-rich solids or gas, though therm dissociation makes the measurement hard.

Free retrievals prefer fitting the NUV feature with Fe II rather than SiO, though SiO was preferred in chemical equilibrium. Either way, it appears that enormous NUV absorption may not be rare among ultra-hot planets.

I'm very excited to be able to share Yayaati Chachan's Hubble/WFC3 transit spectrum of ultra-hot Jupiter KELT-20b.

Using *all* of WFC3's grisms, we get a 0.2-1.7 micron spectrum showing absorption by metals at in the UV and only weak absorption by water in the IR. 🔭🪐

To aid in that interpretation, we carried out a state-of-the-art stellar analysis using our ultra-precise a/R* measurement from JWST combined with ground-based archival spectra and photometry. This revealed that the WASP-178 system is relatively young, at only about 100 Myr old!

We ran a bunch of different retrieval scenarios, which sometimes agreed and sometimes disagreed, but some useful threads were identified: all retrievals wanted 1) sub-solar [C/H] and [Ti/H] and 2) solar-to-super-solar [O/H] and [Si/H]. This would roughly correspond to "rock-laden" enrichment.

The spectrum is kind of unusual: the IR JWST/NIRSpec/G395H is relatively benign with muted H2O and CO absorption. The NIR from HST/WFC3 seems dominated by H-, but then the UV has this absolutely enormous absorption feature from some combination of SiO, Fe, and Mg.

@jarron.bsky.social Now with directly imaged planets! DI planets with uncertain periods are placed at 1e5 days.

I made a new gif for a new site tracking JWST observations of exoplanets (still a work in progress): jlothringer.github.io/Dashboard.html

What an exciting ~3 years it has been! ✨🔭✨