The Stellar Contamination Survival Guide: Lessons from Interpreting JWST Transmission Spectra of Exoplanet Atmospheres

Ryan MacDonald

University of Michigan

Transmission spectroscopy - a measurement of the wavelength-dependent size of a transiting exoplanet - has proven one of the most powerful techniques to infer the chemical composition of exoplanet atmospheres. JWST Cycle 1 observations have already successfully used transmission spectra to make the first detections of CO2 and SO2 in an exoplanet atmosphere. Ongoing and planned JWST observations will also search for atmospheres around terrestrial exoplanets using this technique. But there is a dark cloud on the horizon. Unocculted active regions on transiting planet host stars - star spots and faculae - can imprint signatures into transmission spectra that can mimic molecular absorption features from the planetary atmosphere. This problem is especially pronounced for cool M-dwarfs, such as TRAPPIST-1, which host many of the most promising rocky planets for atmospheric detection. How should we deal with the challenge of stellar contamination? In this talk, I will present some takeaway lessons from retrieval analyses of several JWST transmission spectra impacted by stellar contamination. I will also offer recommendations for how we can plan future JWST proposals to mitigate stellar contamination.

Date: Jeudi, le 18 mai 2023
Heure: 11:30
Lieu: Pour tous
  Pavillon MIL A-3541