Observations of exoplanetary atmospheres provide a valuable upper boundary condition for studying their interiors.  The species that appear in transmission and emission spectra are formed from the composition of the uppermost convective region minus any condensates and after chemical reactions induced by the lower temperatures and pressures.  As such, if the planet’s atmosphere is depleted in metals compared to its bulk, this indicates the presence of a core or composition gradients in its interior.  Further, disequilibrium chemistry can be indicative of fast mixing resulting from a hot interior.  JWST observations of WASP-107 b show exactly this, which we interpret as being the result of strong heating from eccentricity tides.  Further, the atmospheric abundance measurements are precise enough to indicate the presence of a roughly 12 Earth mass core, a reasonable value in the core-accretion context, though we do not know whether or not it is made of many layers.  I’ll also discuss how this type of work can be extended to directly-imaged planets, thanks to the increasing quality of those observations and the availability of RV and astrometric mass measurements.  While true brown dwarf companions are likely to be roughly stellar throughout their bulk, planets of a few Jupiter masses may still be significantly enhanced and not necessarily fully-mixed; this will provide a new avenue for investigating these objects that sit between the core-accretion and nebular collapse regimes.

Host: Megan Delamer

Seminar held in 538 Davey or please email CEHW-SEMINAR-QUESTIONS@lists.psu.edu to attend virtually.