Assistant Astronomer @STScI researching exoplanet and brown dwarf atmospheres. (he/him)
Joined September 2009
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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 hope this is just the start at looking at these population-level trends, now with more robust and reliable measurements. We'll continue to collect measurements as they become available and update the table. We plan to extend this to include free retrieval results.
Take a look at the paper, now accepted to AJ, for more info: arxiv.org/abs/2510.26785. The code and calculations used in the paper are available at the GitHub linked above. The data used in the paper is available here: jlothringer.github.io/LExACo…
Registration is open now!
Abstracts close this Friday for the Fall 2025 STScI Science Workshop on Atmospheric Escape and Replenishment. We'd love to see you in Baltimore in November!
Check it out and let me know if you've any questions.
stsci.edu/contents/events/st…
Josh Lothringer retweeted
Read the latest about JWST's Rocky Worlds Director's Discretionary Time program, including final targets and an upcoming information session: ow.ly/KfoB50WReQu
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.
ALT A plot of a spectrum of transit depth versus wavelength showing large NUV absorption and weak H2O absorption at NIR wavelengths.
We find tentative evidence for a limb asymmetry in the huge NUV feature. 3D GCM models (with mag fields!)
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.
ALT Two histograms showing the posterior constrain on limb asymmetries in the white light curve and NUV spectrum. The NUV spectrum (0.2-0.4) appears to show positive evidence for a limb asymmetry.
ALT Two 2D slices of the 3D global-circulation model, showing the temperature in color for the 0 Gauss and 5.0 Gauss magnetic field models. The 0 Gauss model shows more asymmetry than the 5.0 G model.
And a big shout-out to lead-author Yayaati for seeing this project through from proposal to paper and showing that HST still has lots to say about exoplanet atmospheres in the JWST-era!
Check out the paper here: arxiv.org/abs/2508.10092. Accepted for publication in AJ!
Abstracts close this Friday for the Fall 2025 STScI Science Workshop on Atmospheric Escape and Replenishment. We'd love to see you in Baltimore in November!
Check it out and let me know if you've any questions.
stsci.edu/contents/events/st…
Popping in to say:
🔭 New paper day on the arXiv! arxiv.org/abs/2503.15472
We observed ultra-hot Jupiter WASP-178b with HST and JWST to try to figure out where the planet comes from!
🔭 Because it is more relevant now more than ever, this research was supported by funding from both NASA and NSF which allowed me, four undergraduate students, and two co-authors to spend time analyzing these data.