Dr. Thomas Greene (IPAC)

JWST observations are revealing much about the chemical compositions, disequilibrium chemistry, thermal structures, cloud properties, and energy transport in exoplanet atmospheres. This is leading to improved understanding of their overall physical states and is informing formation scenarios. I will illustrate some progress with results from the JWST MANATEE guaranteed time observations of warm transiting planets ranging from Earth-to-Saturn masses. These include the discovery that the Earth-sized planet TRAPPIST-1 b has no substantial atmosphere, using measured underabundances of methane to constrain vertical temperature profiles, finding and understanding photochemical products (exoplanet smog), constraining the core and internal heat of a Neptune-mass planet from its atmospheric abundances, probing the compositions of mini-Neptune planets (unlike any in our Solar System), finding spatial inhomogeneities on planets' faces, studying global circulation and cloud formation, and investigating planet formation pathways.