Planetary Evaporation Through Evolution

Abstract

Atmosphere escape is observed in the solar system for a variety of objects, including the sun all the way down to Pluto. It should, therefore, come as no surprise that planets orbiting other stars may exhibit similar phenomena, provid- ing an opportunity to explore the effects of atmosphere escape across a range of conditions not encountered in the solar system. Improvements in understanding the upper atmospheres of exoplanets and the time evolution of stellar X-ray to ultraviolet fluxes for a range of stellar masses have, together, enabled careful models of planet evolution that include the impact of atmospheric escape. A clear picture is emerging where some planets are left relatively unscathed, while others may experience substantial planetary evaporation that completely determines their bulk properties and ultimate fate. This chapter introduces some of the basic concepts for understanding the role of atmospheric escape and large-scale planetary evaporation in the long-term evolution of Jupiter-mass down to super- Earth-mass exoplanets.