Studying Stars & Exoplanets with AXIS

How does stellar activity affect the evolution and habitability of exoplanets? The probe class Advanced X-ray Imaging Satellite (AXIS) will have a 1-arcsecond PSF over a 30-arcminute field of view and, in comparison to Chandra, will be 20 times more sensitive to X-ray emission from stars. X-rays are correlated with stellar magnetic activity and rotation – and therefore serve as key tracers of flares, accretion, coronal mass ejections, and EUV emission – knowledge of which is important for modeling atmospheric chemistry and assessing habitability of exoplanets. AXIS is the only probe class mission with the sensitivity and imaging resolution to measure the X-ray luminosity and variability of entire populations of stars down to M-dwarfs in clusters out to kpc distances, which will serve to reconstruct the history of exoplanets’ high-energy environments across different stellar types, ages, metallicities, and environments. AXIS would also provide the unique opportunity to pioneer the field of exoplanet transits in the X-ray, to directly measure the extent of exospheres and evaporating atmospheres.