The Influence of Stellar Variability on the Atmosphere of Proxima Centauri b

We study Earth-like planets in the HZ of M-dwarf stars with a particular focus on the interaction of ionizing radiation with the atmosphere of the planet, which is especially important in the case of very active stars such as Proxima Centauri. Using a 1D approach and assuming an Earth-like N2-O2 base atmosphere, we can quantify the impact of stellar radiation on molecules influenced by biogenic processes such as, e.g., ozone, nitrous oxide, and methane.
A cloud-free radiative-convective photochemistry model provides the temperature-pressure-profile and neutral composition of the base atmosphere. Ion-electron pair production rates in each atmospheric layer are calculated with a simulation toolkit based on Geant4 tailored specifically for parametric studies of the interaction between exoplanetary atmospheres and radiation (of both stellar and galactic origin). Additionally, the toolkit allows us to estimate the absorbed dose rate. Given the pair production rates and base atmosphere, we can apply a 1D stacked box column model of the neutral and ionized atmosphere to obtain the production rates of several important neutral species and determine the long time effect of regularly occurring flaring conditions on atmospheric
concentrations of bioindicators.

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