Thermal Response of A Solar-like Atmosphere to An Electron Beam from A Hot Jupiter: A Numerical Experiment

TL;DR

This study uses a 1D MHD simulation to explore how an electron beam from a hot Jupiter affects a solar-like star's atmosphere, revealing localized heating and increased radiative fluxes, but with luminosity below observed levels.

Contribution

It introduces a numerical experiment modeling the impact of planetary electron beams on stellar atmospheres, highlighting localized heating effects and radiative flux enhancements.

Findings

Warm chromospheric region forms with sufficient beam energy.

Enhanced radiative fluxes in chromosphere and transition region.

Beam-induced luminosity is much smaller than observed stellar emissions.

Abstract

We investigate the thermal response of the atmosphere of a solar-type star to an electron beam injected from a hot Jupiter by performing a 1-dimensional magnetohydrodynamic numerical experiment with non-linear wave dissipation, radiative cooling, and thermal conduction. In our experiment, the stellar atmosphere is non-rotating and is modelled as a 1-D open flux tube expanding super-radially from the stellar photosphere to the planet. An electron beam is assumed to be generated from the reconnection site of the planet's magnetosphere. The effects of the electron beam are then implemented in our simulation as dissipation of the beam momentum and energy at the base of the corona where the Coulomb collisions become effective. When the sufficient energy is supplied by the electron beam, a warm region forms in the chromosphere. This warm region greatly enhances the radiative fluxes corresponding to the temperature of the chromosphere and transition region. The warm region can also intermittently contribute to the radiative flux associated with the coronal temperature due to the thermal instability. However, owing to the small area of the heating spot, the total luminosity of the beam-induced chromospheric radiation is several orders of magnitude smaller than the observed Ca II emissions from HD 179949.