Monday Science Lunch Seminar

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4530 Sterling Hall
@ 12:00 pm - 1:00 pm

An informal seminar series to highlight work from early career researchers from institutions around the world.

Title: Quantifying the Transit Light Source Effect on AU Microscopii
Abstract: AU Mic is an active 24+/-3 Myr pre-main sequence M dwarf in the stellar neighborhood (d=9.7 pc) with a rotation period of 4.9 days. Its two transiting planets, AU Mic b and c, are warm sub-Neptunes on 8.5 and 18.9-day periods, respectively, and are targets of interest for atmospheric observations of young planets. This is a keystone system for studying planetary atmospheres but our understanding of planets is limited by our understanding of their host star. In particular, unocculted heterogeneities like starspots can bias exoplanet transmission observations and mimic signatures of atmospheric absorption. This problem, now known as the Transit Light Source Effect, affects nearly every transmission spectrum we have or will acquire and is especially significant for small planets orbiting cool stars. As such, the future of exoplanet atmospheric characterization depends on our theoretical understanding of stellar surfaces and our observational ability to distinguish between surface features. This talk presents the results of characterizing starspots on AU Mic as a complement to HST/WFC3 observations of AU Mic b. With ground based photometry and out-of-transit spectroscopy, results of modeling spot temperature and filling factor imply significant contamination and underscore the need to better understand exoplanet host stars.

Join via Zoom here.

Organized by: Leon Trapman, Dan Rybarczyk, Nickolas Pingel, & Melinda Soares-Furtado