Morphology of the magnetic field near Titan:: Hybrid model study of the Cassini T9 flyby

We study the deformation and morphology of the magnetic field near Titan by a three-dimensional numerical quasi-neutral hybrid model (HYB-Titan). We analyze two runs, one in which the sub-rotating plasma consists of oxygen (O+) ions and protons (H+) and another with only protons. We find that both cases result in the generation of Alfven wing-like flux tubes. In comparison with the protononly case, the direction and magnitude of the magnetic field in the oxygen-rich flow case are in better agreement with Cassini magnetic field observations during its Titan T9 flyby on Dec. 26, 2006, suggesting that the sub-rotating plasma contained heavy ions. The oxygen-rich run also supports the hypotheses that ( 1) the sub-rotating flow direction was offset by -30 degrees -40 degrees from the ideal rotating flow direction and that ( 2) the spacecraft was magnetically connected to the sunlit side of near-Titan space in the tail when it approached Titan on the T9 flyby.