A model of energy deposition of energetic electrons and EUV emission in the Jovian and Saturnian atmospheres and implications

Abstract

A model of the interaction between incident electron precipitation and H 2 atmospheres is described. The local degraded primary and secondary electron energy distributions are calculated by using the continuous slowing down approximation. The altitude distribution of the ionization rate and various H and EUV H 2 emissions are calculated for four different incident electron spectra. A total EUV H 2 emission efficiency of 10.6 kR/incident erg cm −2 s −1 is obtained for a pure H 2 atmosphere. Comparison with the Voyager Jupiter observations indicates that an incident energy flux of about 8 ergs cm −2 s −1 was present at the time of the encounter if the emission is located in an H 2 ‐dominated region. The local thermospheric heating rate was about 4 ergs cm −2 s −1 for Jupiter and of the order of 0.1 erg cm −2 s −1 for Saturn. A globally averaged atomic hydrogen production rate of ∼1×10 10 atoms/cm² s −1 is induced by the Jovian auroral electron precipitation, largely exceeding the solar EUV dissociation rate.