Magnetosphere of HD 209458 b in the Paraboloid and MHD Models

Abstract The paper presents a comparative analysis of simulations of the magnetosphere of the hot Jupiter HD 209458 b performed with a paraboloid model and with ideal magnetohydrodynamic (MHD) modeling. Two flow regimes around the hot Jupiter—super-Alfvenic and sub-Alfvenic—are considered, since the exoplanet is located near the Alfvén radius. For the super-Alfvenic case, the paraboloid model reproduces a comet-like magnetosphere with closed field lines on the dayside and an elongated tail on the nightside, which is consistent with the results of the MHD modeling (a shock-type intrinsic magnetosphere according to the authors’ classification). In the sub-Alfvenic regime, both models show the formation of pronounced Alfvén wings stretched along the star–planet line for the chosen orientation of the magnetic field of the stellar wind. The fundamental difference between the approaches is emphasized: the paraboloid model efficiently and compactly describes the geometry and topology of the magnetic field (convenient for operational analysis and interpretation of observations), whereas the MHD simulations allow one to account for the interaction of the plasma with the stellar wind and its magnetic field.