Hot Jupiter Magnetospheres
George B. Trammell, Phil Arras, Zhi-Yun Li (Department of Astronomy,, University of Virginia)

TL;DR
This paper models the magnetospheres of hot Jupiters using 3D MHD simulations, revealing how magnetic fields influence atmospheric structure, transit signals, and mass loss, with implications for exoplanet observations.
Contribution
It introduces a 3D isothermal magnetohydrodynamic model for hot Jupiter magnetospheres, including a detailed analysis of the dead zone, wind zone, and magnetic effects on transit spectra.
Findings
Dead zone size estimated at 1-10 planetary radii.
Transit depths of 5-10% for certain conditions.
Magnetic fields increase transit signals and reduce mass loss.
Abstract
(Abridged) The upper atmospheres of close-in gas giant exoplanets are subjected to intense heating/tidal forces from their parent stars. Atomic/ionized hydrogen (H) layers are sufficiently rarefied that magnetic pressure may dominate gas pressure for expected planetary magnetic field strength. We examine the magnetospheric structure using a 3D isothermal magnetohydrodynamic model that includes: a static "dead zone" near the magnetic equator containing magnetically confined gas; a "wind zone" outside the magnetic equator in which thermal pressure gradients and the magneto-centrifugal-tidal effect give rise to transonic outflow; and a region near the poles where sufficiently strong tidal forces may suppress transonic outflow. Using dipole field geometry, we estimate the size of the dead zone to be ~1-10 planetary radii for a range of parameters. To understand appropriate base conditions…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astro and Planetary Science · Astrophysics and Star Formation Studies
