Physical Society Colloquium

New Views of Cool Atmosphere Physics and Chemistry from JWST

Jonathan Fortney

Astronomy and Astrophysics
University of California Santa Cruz

Giant planets and brown dwarfs are astrophysical objects with different formation locations – planets in disks and brown dwarfs (we think) in giant molecular clouds.  These different objects transition across the very same range of Teff, with planets strongly influenced by their parent star’s heating from “above,” while brown dwarfs inexorably cool from their interior, which warms their atmospheres from “below.”  This major energy difference can drive important differences between atmospheres.  JWST has been revolutionizing our understanding of these cool atmospheres, and in this talk I will discuss a range of modeling work that aims to confront a variety of high signal-to-noise spectral observations, in particular for objects below Teff = 1000 K, where a number of major chemical transitions in these atmospheres occur.  Our work uncovers a wide range of physical process, including vertical mixing, photochemistry, and tidal heating, which can all effect the structure and chemistry of cool atmospheres.  The significant diversity in spectra stress-test our models in unique ways.