SSGS: Mapping Spots on the Stellar Surface with Exoplanet Transmission Spectrum Observations (W. Waalkes)

Date: Apr 14, 2026
Time: 11:00 AM - 12:00 PM (Local Time Germany)
Speaker: William Waalkes
MPS
Location: Max-Planck-Institut für Sonnensystemforschung
Room: Auditorium
Host: Robert Cameron

A picture of a part of the limb of the Sun with a large protuberance towering above the surface to the left of the limb

AU Microscopii is among the most heavily spotted stars while hosting one of the best targets for atmospheric characterization of sub-Neptune worlds, given the temperature (3700 K), proximity (9.7 pc), and age (20-25 Myr) of the system. HST/WFC3 transmission spectrum observations of its innermost planet, AU Mic b, are expected to exhibit strong atmospheric absorption, but these signals are obscured by various forms of stellar activity. In this talk, I will discuss a method of decontaminating the transmission spectrum that uses chromatic information in the spectroscopic light curves to characterize the stellar surface alongside the planetary atmosphere.