The impact of CMEs and flares on the atmospherere of close-in exoplanets: comparison with observations

VIDOTTO, ALINE; HAZRA, GOPAL; CAROLAN, STEPHEN; VILLARREAL D'ANGELO, CAROLINA; MANCHESTER, WARD

Congreso; 44th COSPAR Scientific Assembly; 2022

High-energy stellar irradiation can photoevaporate planetary atmospheres, which can be observed in spectroscopic transits of hydrogen lines. For the close-in giant exoplanet HD189733b, multiple observations in the Ly-alpha line have shown that atmospheric evaporation is variable, going from undetected to enhanced evaporation in a 1.5-yr interval. Coincidentally or not, when HD189733b was observed to be evaporating, a stellar flare had just occurred 8 h prior to the observation. This led to the question of whether this temporal variation in evaporation occurred due to the flare, an unseen associated CME, or even the simultaneous effect of both. In this work, we investigate the impact of flares (radiation), winds, and CMEs (particles) on the atmosphere of HD189733b using three-dimensional radiation hydrodynamic simulations that self-consistently include stellar photon heating. We find that the flare alone cannot explain the observed high blueshifted velocities seen in the Ly-alpha. The CME, however, leads to an increase in the velocity of escaping atmospheres, enhancing the blueshifted transit depth