Ionization and transport in partially ionized multicomponent plasmas: Application to atmospheres of hot Jupiters

TL;DR

This paper models ionization and transport in partially ionized multicomponent plasmas, applying it to hot Jupiter atmospheres to explain observed planetary inflation through revised Ohmic heating calculations.

Contribution

It introduces a comprehensive approach to calculate plasma composition and transport properties considering multiple species and reactions, applied specifically to hot Jupiter atmospheres.

Findings

Plasma composition varies with density and temperature.

Electrical conductivity influences Ohmic heating in hot Jupiter atmospheres.

Higher interior temperatures could enhance conductivity and planetary inflation.

Abstract

We study ionization and transport processes in partially ionized multicomponent plasmas. The plasma composition is calculated via a system of coupled mass action laws. The electronic transport properties are determined by the electron-ion and electron-neutral transport cross sections. The influence of electron-electron scattering is considered via a correction factor to the electron-ion contribution. Based on this data, the electrical and thermal conductivity as well as the Lorenz number are calculated. For the thermal conductivity, we consider also the contributions of the translational motion of neutral particles and of the dissociation, ionization, and recombination reactions. We apply our approach to a partially ionized plasma composed of hydrogen, helium, and a small fraction of metals (Li, Na, Ca, Fe, K, Rb, Cs) as typical for hot Jupiter atmospheres. We present results for the plasma composition and the transport properties as function of density and temperature and then along typical P-T profiles for the outer part of the hot Jupiter HD 209458b. The electrical conductivity profile allows revising the Ohmic heating power related to the fierce winds in the planet's atmosphere. We show that the higher temperatures suggested by recent interior models could boost the conductivity and thus the Ohmic heating power to values large enough to explain the observed inflation of HD 209458b.