Published October 11, 2021 | Version v1
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Habitability and loss of hydrogen-helium atmospheres of small planets - the K dwarf advantage

  • 1. Leibniz Institute for Astrophysics Potsdam (AIP)


Contributed talk at PLATO Mission Conference 2021.


Evaporation of hydrogen and helium is now directly observable for exoplanets of Jupiter and Neptune size, by using high-resolution spectral observations in the ultraviolet and in the infrared. For even smaller planets, the ongoing loss of a primordial hydrogen-helium atmosphere has not been directly observed yet, but is thought to be relevant for the formation of a habitable atmosphere for life as we know it. The observability of helium escape depends critically on an exoplanet's irradiation in the high-energy regime. M dwarfs, typically a favourite target for habitable zone exoplanet observations, are at a disadvantage here due to their coronal elemental abundance patterns. However, K dwarfs present a suitable starting point for detecting helium escape from planets in their habitable zones, due to their favorable coronal abundances and their higher magnetic activity level compared to G dwarfs. I will discuss relevant examples and outline the impact that modern high-energy surveys can have on the optimal target selection for observing exoplanetary atmospheric escape.


Research funded by the German "Leibniz-Gemeinschaft" under project number P67/2018.



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