Evaluation system of Stellar Superflares impacts on Planetary Habitability

Abstract:

We present the comprehensive quantitative impact evaluation system of stellar flares on the habitability factors with an emphasis on the impact of stellar proton events applicable for all 45 potential habitable planets classified as CHZ. We derive the maximum flare energy from stellar star spot sizes and examine the impacts of flare-associated ionizing radiation on CO₂, H₂, and N₂+ O₂-rich atmospheres of a number of well-characterized terrestrial type exoplanets. Our simulations based on the Particle and Heavy Ion Transport code System suggest that the estimated ground-level dose for each planet in the case of terrestrial-level atmospheric pressure (1 bar) for most of exoplanets do not exceed the critical dose for complex (multicellular) life to persist, even for the planetary surface of Proxima Centauri b, Ross-128 b, and TRAPPIST-1 e. Large fluxes of coronal XUV emission from active stars induce high atmospheric escape rates from close-in exoplanets, suggesting that the atmospheric depth can be substantially smaller than that on Earth. In this study we also consider that the atmospheric escape may be induced both XUV emission and frequency of flares. By considering both impacts some so-called habitable planets reaches near fatal levels with annual frequency of flare occurrence from their host stars. The system can be extended for evaluating historical transition of habitability of terrestrial planets in our solar system, especially for the Marsian surface radiation condition.