Topic: Cool Stars as Exoplanet Hosts
Long considered the “low-rent district” of the Galaxy, there has been a resurgence of interest in the habitability of planets around M dwarfs. As we better understand the nature of the planet–star interactions that affect habitability, many of the initial concerns, including the effects of tidal locking and stellar activity, have been lessened, although issues such as atmospheric retention against stellar winds remain. However, despite the potentially hostile complications associated with orbiting an M dwarf, planet detection techniques are more sensitive to smaller planets around smaller stars. It is likely then that the first nearby potentially habitable terrestrial planet amenable to spectroscopic follow-up by missions such as JWST will be found orbiting an M dwarf in our Solar neighborhood. To prioritize planetary targets for observational and theoretical characterization, and to best interpret the observations returned, it is therefore important to understand the factors that affect M dwarf planet habitability. Because the M dwarf habitable zone is close-in, planetary habitability is influenced by both radiative and gravitational interactions with the parent star. In this presentation I will review our understanding of stellar interactions with the atmospheres and interiors M dwarf planets, and how these interactions affect planetary habitability and the detection of biosignatures. I will also discuss areas of study where progress in our understanding of cool stars would enhance our ability to study and understand habitability for planets orbiting M dwarfs.