The Interaction of Venus-like, M-dwarf Planets with the Stellar Wind of Their Host Star

TL;DR

This study models how Venus-like, non-magnetized exoplanets around M-dwarf stars interact with stellar wind, revealing deep wind penetration and potential long-term atmospheric erosion.

Contribution

It introduces a multi-species MHD model to analyze stellar wind interactions with non-magnetized exoplanets and assesses atmospheric loss over geological timescales.

Findings

Deep stellar wind penetration up to hundreds of kilometers.

Atmospheric mass loss is negligible over planet's lifetime.

Ion acceleration could cause significant atmospheric erosion over a billion years.

Abstract

We study the interaction between the atmospheres of Venus-like, non-magnetized exoplanets orbiting an M-dwarf star, and the stellar wind using a multi-species Magnetohydrodynaic (MHD) model. We focus our investigation on the effect of enhanced stellar wind and enhanced EUV flux as the planetary distance from the star decreases. Our simulations reveal different topologies of the planetary space environment for sub- and super-Alfvenic stellar wind conditions, which could lead to dynamic energy deposition in to the atmosphere during the transition along the planetary orbit. We find that the stellar wind penetration for non-magnetized planets is very deep, up to a few hundreds of kilometers. We estimate a lower limit for the atmospheric mass-loss rate and find that it is insignificant over the lifetime of the planet. However, we predict that when accounting for atmospheric ion acceleration, a significant amount of the planetary atmosphere could be eroded over the course of a billion years.