The study of the polarization of the atmospheric emissions in the Jovian system

The polarization of atmospheric emissions can occur through several anisotropic processes. One is the polarization by electronic impact. Up to now, the polarization of the planetary atmospheric glow has not been the aim of space experiments. However, it can be used to diagnose the composition of the atmosphere and / or the excited mechanisms and thus, the suprathermal particle content. This is often use in stellar atmospheres, but barely in planetology. In the Jovian system, the polarization can appear in the auroral emissions - FUV due to the composition of the atmosphere - because of electron impacts. Measuring it will allow to obtain information on the pitch angle of the hot precipitated electrons, their energy and the proportion of mission from primary electrons against secondary. Depolarization effects - essentially by radiative transfer- must be taken into account. However, one cannot exclude a-priori that polarization occurs also at lowest latitudes, due to the strength of the magnetic field, which is the main source of transport anisotropy. We therefore propose to add a polarimeter on a UV spectrometer to observe the polarization of the emission lines