Title:
The distribution of hot hydrogen atoms produced by electron and proton precipitation in the Jovian aurora
Authors:
Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.; Gladstone, G. R.; Waite, J. H., Jr.
Journal:
Journal of Geophysical Research, Volume 101, Issue E9, September 25, 1996, pp.21157-21168

Abstract

The energy distribution functions of nonthermal thermospheric hydrogen atoms are calculated for electron and proton precipitation in the Jovian aurora. A numerical model taking into account the production, elastic and inelastic relaxation and transport processes for hot H atoms is developed. This model is based on a Monte Carlo solution of the non linear Boltzmann equation for hot H atoms produced by electron and proton impact on H and H$_2$ and exothermic chemical reactions. The distribution functions show a much higher energy tail for proton than electron precipitation. It is shown that the steady state flux of hot atoms (E $\ge$ 2eV) is essentially isotropic. The peak and column hot H densities are about 3 $\times$ 10$^5$ cm $^{-3}$ and 1 $\times$ 10$^{14}$ cm $^{-2}$ for a 100 erg cm$^{-2}$ s$^{-1}$ precipitation (combining hard (22 keV) and soft (0.2 keV) electrons mixed with a 10 erg cm$^{-2}$ s$^{-1}$ flux of soft (0.3 keV) protons). These column densities, coupled with the wide range of hot H atom energies, may play an important role in the formation of the Ly-$\alpha$ line profile. Multiple scattering in the wings of the Ly-$\alpha$ line by the fast H atoms is a possible explanation of the broad Ly-$\alpha$ profile observed in the Jovian aurora with the HST.