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EP: Fachverband Extraterrestrische Physik

EP 2: Planets in their Environment

EP 2.5: Vortrag

Dienstag, 27. Februar 2024, 15:45–16:00, ELP 1: HS 1.22

Europa's asymmetric electron temperature — •Stephan Schlegel and Joachim Saur — University of Cologne, Cologne, Germany

Far ultraviolet emissions of Jupiter's moon Europa have been used as a diagnostic for its atmosphere and plasma environment. Hubble Space Telescope observations have shown time and spacial variability of the OI1356 oxygen line. The observations suggest that the side of Europa facing the dense plasma sheet is brighter at this wave length. The brightness is associated with electron density, electron temperature and neutral particle density along the line of sight. Therefore, the question arises, which effect controls this asymmetry in the brightness.

We conducted a study of the electron temperature and density around Europa. For that purpose we carried out simulations of the system that solve the ideal MHD equations and inferred the electron temperature. In our study, the electrons are cooled down by the interaction with the atmosphere and are reheated by heat conduction along the magnetic field lines. The asymmetry in available thermal energy between the plasma sheet facing and opposite site leads to a fast cooling of the latter and leads to an asymmetry in electron temperature. This could explain the asymmetries in the HST observations.

Keywords: Europa; Aurora; MHD; Plasma; Jupiter