Antonija Oklopčić – Harvard University
Probing the Escaping Atmospheres of Exoplanets
Atmospheric escape is an important process in the evolution of atmospheres of extrasolar planets, especially those orbiting very close to their host stars. However, many aspects of atmospheric escape in exoplanets remain poorly understood, in part due to a small number of direct observations that have been available until recently, obtained mostly via transit spectroscopy in the difficult-to-observe hydrogen Lyman-alpha line. In recent theoretical work, we demonstrated that the absorption line of helium at 1083 nm can be used as a powerful new diagnostic of extended and escaping atmospheres. Since then, large absorption signals in the helium 1083 nm line have been observed in several exoplanets. I will discuss how we can use theoretical models to provide the physical interpretation for the observed 1083 nm absorption signals and place constraints on the physical properties of extended exoplanet atmospheres and their mass-loss rates. These observations can help us improve our understanding of the processes that drive atmospheric mass loss and, consequently, influence the evolution of exoplanets and the demographics of exoplanetary systems.