Titan's Midrange Magnetotail from Cassini Observations and Hybrid Modeling

Abstract:

We study Titan's plasma interaction during Cassini's midrange tail encounters T9, T63 and T75. During each of these flybys, the Cassini Plasma Spectrometer detected a peculiar split signature in Titan's pickup tail, i.e. the spacecraft passed through two spatially separated cold ion populations of different masses. Whether this might be an omnipresent feature of Titan's plasma interacting or a result of non-stationary upstream conditions is still unclear. To explain these features, we apply the hybrid simulation code AIKEF. The latest version of this code includes chemical reactions, a realistic and statistically consistent photoionization model and recombination for a sophisticated description of the ionospheric composition of Titan. To validate the ionosphere model, we compare its output against measurements of the magnetic field and the electron density from the T70 flyby, which reached the lowest altitude of all flybys and had nearly ideal upstream conditions with the magnetic field pointing southward.