Abstract

Planets orbiting small, nearby stars represent our best – and only – opportunity to search for biosignatures in the current decade.  With the recent start of JWST science operations, precise atmospheric constraints for terrestrial worlds orbiting M dwarfs are finally within reach.  JWST is devoting > 200 hours in Cycle 1 towards the study of rocky worlds, all of which transit M dwarfs, and that number is expected to grow in future cycles after the first detections of secondary atmospheres.  By decade’s end, we will have performed the first initial reconnaissance of potentially-habitable exoplanets, but it remains to be seen if we will have the comprehensive modeling framework necessary to correctly interpret the results and avoid making premature claims of detecting signs of life.

I will discuss how observation and modeling efforts are working in tandem to understand the composition and diversity of M-dwarf exoplanet atmospheres.  This includes sharing transmission spectra from some of JWST’s first rocky exoplanet observations and dueling interpretations that hinge on our understanding of the stars themselves.  Has JWST detected its first secondary atmosphere?  Knowing whether these strange new worlds host appreciable atmospheres will help advance the search for life in bold new ways.