Bremen 2017 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 10: Planeten und kleine Körper I
EP 10.3: Vortrag
Donnerstag, 16. März 2017, 09:15–09:30, GW2 B2880
A Fluid-Kinetic Model of Callisto's Ionospheric Electrons — •Oliver Hartkorn1, Joachim Saur1, and Darrell F. Strobel2 — 1Institute of Geophysics and Meteorology, University of Cologne, Pohligstr. 3, 50969 Cologne, Germany — 2Department of Earth and Planetary Sciences, Johns Hopkins University, MD 21210, Baltimore, USA
We develop a model of the ionospheric electron population of Jupiter's moon Callisto using a prescribed neutral atmosphere composed of O2, CO2 and H2O. A kinetic description of ionospheric suprathermal electrons coupled with a fluid description of ionospheric thermal electrons is well suited to jointly analyze and interpret observations of electron density and atmospheric UV emission. Accordingly, we calculate the electron energy distribution function at each point in the ionosphere by solving the Boltzmann equation for suprathermal electrons and the continuity and energy equation for thermal electrons. We assume a stationary balance between local sources and sinks of electrons and electron energy neglecting electron transport. We consider photoionization, which is the dominant ionospheric electron source, and secondary ionization processes. Our calculations yield electron densities and electron impact generated UV emissions from Callisto's atmosphere. Comparisons between our modeled UV emission intensities and Hubble Space Telescope observations allow to draw conclusions on the atmospheric density of Callisto. Moreover, a joint comparison with HST observations and radio occultation observations of the Galileo spacecraft shows that Callisto's atmosphere possesses a day night asymmetry.