Modeling Stellar Proton Event-induced particle radiation dose on close-in exoplanets

TL;DR

This study models how stellar proton events from superflares affect radiation levels on close-in exoplanets, impacting their habitability by potentially causing frequent extinction events without complete sterilization.

Contribution

It introduces Monte Carlo simulations to quantify SPE-induced radiation doses on exoplanets considering atmospheric and magnetic variations.

Findings

Radiation doses vary widely with atmospheric and magnetic properties.

Close-in exoplanets with substantial atmospheres may withstand superflares without sterilization.

Proxima Centauri b's habitability is affected by stellar proton interactions, possibly leading to extinction events.

Abstract

Kepler observations have uncovered the existence of a large number of close-in exoplanets and serendipitously of stellar superflares with emissions several orders of magnitude higher than those observed on the Sun. The interaction between the two and its implications on planetary habitability is of great interest to the community. Stellar Proton Events interact with planetary atmospheres, generate secondary particles and increase the radiation dose on the surface. This effect is amplified for close-in exoplanets and can be a serious threat to potential planetary life. Monte Carlo simulations are used to model the SPE-induced particle radiation dose on the surface of such exoplanets. The results show a wide range of surface radiation doses on planets in close-in configurations with varying atmospheric column depths, magnetic moments and orbital radii. It can be concluded that for close-in exoplanets with sizable atmospheres and magnetospheres, the radiation dose contributed by stellar superflares may not be high enough to sterilize a planet (for life as we know it) but can result in frequent extinction level events. In light of recent reports, the interaction of hard-spectrum SPEs with the atmosphere of Proxima Centauri b is modeled and implications on its habitability is discussed.