On possible types of magnetospheres of hot Jupiters

Abstract

We show that the orbits of exoplanets of the "hot Jupiter" type, as a rule, are located close to the Alf\'{v}en point of the stellar wind of the parent star. At this, many hot Jupiters can be located in the sub-Alf\'{v}en zone in which the magnetic pressure of the stellar wind exceeds its dynamic pressure. Therefore, magnetic field of the wind must play an extremely important role for the flow of the stellar wind around the atmospheres of the hot Jupiters. This factor must be considered both in theoretical models and in the interpretation of observational data. The analysis shows that many typical hot Jupiters should have shock-less intrinsic magnetospheres, which, apparently, do not have counterparts in the Solar System. Such magnetospheres are characterized, primarily, by the absence of the bow shock, while the magnetic barrier (ionopause) is formed by the induced currents in the upper layers of the ionosphere. We confirmed this inference by the three-dimensional numerical simulation of the flow of the parent star stellar wind around the hot Jupiter HD 209458b in which we took into account both proper magnetic field of the planet and magnetic field of the wind.