On the influence of magnetic fields in neutral planetary wakes

We present a 3D magnetohydrodynamic study of the effect that stellar and planetary magnetic fields have on the calculated Lya absorption during the planetary transit, employing parameters that resemble the exoplanet HD209458b. We assume a dipolar magnetic field for both the star and the planet, and use the Parker solution to initialize the stellar wind. We also consider the radiative processes and the radiation pressure. We use the numerical MHD code Guacho to run several models varying the values of the planetary and stellar magnetic moments within the range reported in the literature. We found that the presence of magnetic fields influences the escaping neutral planetary material spreading the absorption Lya line for large stellar magnetic fields.