Tim Lichtenberg - "Exoplanetary Geophysics" (IvS seminar 08/10/2026)

The last few years of JWST observations have turned the low-mass exoplanet census into an empirical testbed for expanding our understanding of planetary geophysics. I will present some recent results from our groups efforts on better characterizing and charting the evolution of young and evolved low-mass exoplanets, with a focus on high-temperature lava worlds, super-Earths, and sub-Neptune exoplanets. A few key trends emerge: the sub-Neptune population is likely dominantly molten beneath thick insulating hydrogen layers; even for lower-mass super-Earths the longevity of fully molten internal states can reach Gyrs; and residual secondary atmospheres on close-in super-Earths trend toward CO2 and SO2 dominated volatile compositions. I will discuss the connection with the internal geochemistry and geophysics of super-Earth exoplanets and interpret the surprising trend that higher irradiated planets show increasing evidence for atmospheres.