3D modelling of the impact of stellar activity on tidally locked terrestrial exoplanets: atmospheric composition and habitability
Robert J. Ridgway, Maria Zamyatina, Nathan J. Mayne, James Manners, F. Hugo Lambert, Marrick Braam, Benjamin Drummond, Éric Hébrard, Paul I. Palmer, K. Koháry
Abstract
ABSTRACT Stellar flares present challenges to the potential habitability of terrestrial planets orbiting M dwarf stars through inducing changes in the atmospheric composition and irradiating the planet’s surface in large amounts of ultraviolet light. To examine their impact, we have coupled a general circulation model with a photochemical kinetics scheme to examine the response and changes of an Earth-like atmosphere to stellar flares and coronal mass ejections. We find that stellar flares increase the amount of ozone in the atmosphere by a factor of 20 compared to a quiescent star. We find that coronal mass ejections abiotically generate significant levels of potential bio-signatures such as N2O. The changes in atmospheric composition cause a moderate decrease in the amount of ultraviolet light that reaches the planets surface, suggesting that while flares are potentially harmful to life, the changes in the atmosphere due to a stellar flare act to reduce the impact of the next stellar flare.