MAGNETOSPHERES OF " HOT JUPITERS " : THE IMPORTANCE OF MAGNETODISKS IN SHAPING A MAGNETOSPHERIC OBSTACLE

M. L. Khodachenko (1) , I Alexeev (2) , E Belenkaya (2) , H Lammer (1) , Jean-Mathias Griessmeier (3) , M Leitzinger (4) , P Odert (1, 4) , T Zaqarashvili (2) , H.O. Rucker (1)

1 IWF - Space Research Institute of Austrian Academy of Sciences
2 SINP - D.V. Skobeltsyn Institute of Nuclear Physics
3 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
4 IGAM - Institute for Geophysics, Astrophysics and Meteorology [Graz]

Weak intrinsic magnetic dipole moments of tidally locked close-in giant exoplanets (" hot Jupiters ") have been shown in previous studies to be unable to provide an efficient magnetospheric protection for their expanding upper atmospheres against the stellar plasma flow, which should lead to significant non-thermal atmosphere mass loss. The present work provides a more complete view of the magnetosphere structure of " hot Jupiters, " based on a paraboloid magnetospheric model (PMM). Besides the intrinsic planetary magnetic dipole, the PMM considers among the main magnetic field sources also the electric current system of the magnetotail, magnetopause currents, and the ring current of a magnetodisk. Due to the outflow of ionized particles from the hydrodynamically expanding upper atmosphere, " hot Jupiters " may have extended magnetodisks. The magnetic field produced by magnetodisk ring currents dominates above the contribution of an intrinsic magnetic dipole of a " hot Jupiter " and finally determines the size and shape of the whole magnetosphere. A slower-than-the-dipole-type decrease of the magnetic field with the distance forms the essential specifics of magnetodisk-dominated magnetospheres of " hot Jupiters. " This results in their 40%–70% larger scales compared to those traditionally estimated by only the planetary dipole taken into account. Therefore, the formation of magnetodisks has to be included in the studies of the stellar wind plasma interaction with close-in exoplanets, as well as magnetospheric protection for planetary atmospheres against non-thermal escape due to erosion by the stellar plasma flow. Key words: planets and satellites: magnetic fields – planets and satellites: physical evolution – planets and satellites: rings – planet–star interactions

Domaines: Astrophysique [astro-ph]

M. L. Khodachenko, I Alexeev, E Belenkaya, H Lammer, Jean-Mathias Griessmeier, et al.. MAGNETOSPHERES OF " HOT JUPITERS " : THE IMPORTANCE OF MAGNETODISKS IN SHAPING A MAGNETOSPHERIC OBSTACLE. The Astrophysical Journal, 2012, 744 (70), 16 p. ⟨10.1088/0004-637X/744/1/70⟩. ⟨insu-01351029⟩