3D hydrodynamics simulations of GJ436b: constraining the planetary wind parameters through spectral lines

VILLARREAL D'ANGELO, CAROLINA; VIDOTTO, ALINE

Reikiavik

Conferencia; Extreme Solar Systems IV; 2019

We present the results of the unpublished first 3D hydrodynamics simulations of GJ436 planetary system. These simulations take into account the stellar and planetary wind interaction and include the process of charge-exchange, radiation pressure and photoionisation.  With the output of the simulations we can compute syntethic Ly-alpha transit profiles that we compare with the observations. We show that observed absorption profiles in Ly-alpha can be reproduced in a hydrodynamic scenario where the interaction of both winds forms a shock ahead of the planet.  We also present the constrained parameters obtained for the planetary wind and the influence that charge-exchange and radiation pressure have on the escaping planetary material. The new derived values are not in agreement with the ones presented in the work of Bourrier et al. (2016), showing that the observations in Ly-alpha alone can not be used to constrain the planetary wind parameters. In this sense, we also explore synthetic observations of the H-alpha line during transit.