Effects of Charge Exchange on the Evaporative Wind of HD 209458b

Abstract

The role of charge exchange in shaping exoplanet photoevaporation remains a topic of contention. Exchange of electrons between stellar wind protons from the exoplanet's host star and neutral hydrogen from the planet's wind has been proposed as a mechanism to create "energetic neutral atoms" (ENAs), which could explain the high absorption line velocities observed in systems where mass loss is occurring. In this paper we present results from 3D hydrodynamic simulations of the mass loss of a planet similar to HD 209458b. We self-consistently launch a planetary wind by calculating the ionization and heating resulting from incident high-energy radiation, inject a stellar wind into the simulation, and allow electron exchange between the stellar and planetary winds. We predict the potential production of ENAs by the wind-wind interaction analytically, then present the results of our simulations, which confirm the analytic limits. Within the limits of our hydrodynamic simulation, we find that charge exchange with the stellar wind properties examined here is unable to explain the absorption observed at high Doppler velocities.

arXiv admin note: text overlap with arXiv:1906.00075

References in corpus (7)

• Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
• Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations
• Simulating Magnetohydrodynamical Flow with Constrained Transport and Adaptive Mesh Refinement; Algorithms & Tests of the AstroBEAR Code
• Global 3D hydrodynamic modeling of in-transit Lyα absorption of GJ436b
• Two regimes of interaction of a Hot Jupiter's escaping atmosphere with the stellar wind and generation of energized atomic hydrogen corona
• Lyα Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions
• Hydrodynamical interaction of stellar and planetary winds: effects of charge exchange and radiation pressure on the observed Ly$\alpha$ absorption

Cited by in corpus (4)

• The fundamentals of Lyman-alpha exoplanet transits
• Space Weather-driven Variations in Ly$\alpha$ Absorption Signatures of Exoplanet Atmospheric Escape: MHD Simulations and the Case of AU Mic b
• Using Lyman-$\alpha$ transits to constrain models of atmospheric escape
• Star-Planet Interactions: A Computational View