On the star-magnetosphere interaction of close-in exoplanets

Numerical simulations using a resistive MHD code are performed in order to investigate the interaction of the magnetospheres of hot Jupiters (or close-in extrasolar giant planets) with the central host stars. Because of the sub-Alfvénic nature of the stellar wind outflow at the orbital positions of these close-in exoplanets, no bow shock would form. When the orientation of the stellar coronal magnetic field is favorable to strong coupling with magnetic reconnection, the power (∼10²⁷ ergs s^-1) generated could reach the level of a typical solar flare. As a particular type of star-planet atmospheric interaction, as investigated by Cuntz, Saar, & Musielak, magnetospheric interaction as studied in this Letter could lead to extensive energy injection into the auroral zones of the exoplanets, producing massive atmospheric escape process as recently detected.