Effects of stellar winds on spectroscopic transits of close-in exoplanets

VIDOTTO, ALINE; CAROLAN, STEPHEN; VILLARREAL D'ANGELO, C.; KUBYSHKINA, DARIA; HAZRA, GOPAL; ALLAN, ANDREW

Congreso; 44th COSPAR Scientific Assembly; 2022

The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape, resulting in planetary mass loss. However, stellar winds can shape and even prevent atmospheric escape, affecting observable signatures of escape such as Lyman-alpha and H-alpha line profiles. In this work, we simulate atmospheric escape of close-in exoplanets using 3D magnetohydrodynamics simulations to investigate how they are affected by stellar winds. We show that, although younger hot-Jupiters experience higher levels of atmospheric escape, owing to a favourable combination of higher irradiation levels and weaker planetary gravity, stellar winds are also stronger at this young age, which can act as to reduce escape rates of young exoplanets. Even when this reduction is not significant, we demonstrate that transit signatures can be erased due to the presence of a stellar wind and that neglecting stellar winds in the interpretation of spectroscopic transits can lead to underestimation of planetary escape rates