Sillanpää, I.; Young, D.; Wilson, R.; Crary, F.; Bertucci, C.; Dougherty, M.; Wellbrock, A.; Coates, A.; Kallio, E.; Jarvinen, R.; Janhunen, P.

SILLANPÄÄ, I.; YOUNG, D.; WILSON, R.; CRARY, F.; BERTUCCI, C.; DOUGHERTY, M.; WELLBROCK, A.; COATES, A.; KALLIO, E.; JARVINEN, R.; JANHUNEN, P.

Congreso; AGU Fall Meeting 2008; 2008

Titan's ionosphere and exosphere interact with the rotating plasma flow of the Saturn's magnetosphere. The plasma flow is magnetized by Saturn's magnetic field but also disturbed by the dynamics of the outer magnetosphere; e.g. the location of the plasma sheet and the motion of the magnetopause due to varying solar wind pressure. These cause changes in the density and velocity of the plasma flow as well as in the direction of the ambient magnetic field. Furthermore, near the magnetospheric current sheet (i.e. in the magnetodisk) oxygen and water-group ions have often higher density than hydrogen ions whereas outside the magnetodisk these heavy ion components are not detected and consequently H+ dominates. Cassini's T15 flyby of Titan's close wake on July 2, 2006 is studied using CAPS ion spectrometer (IMS) and magnetometer (MAG) data. The plasma flow was composed of water-group ions (0.09±0.05 cm-3) and H+ (0.07±0.03 cm-3) with the flow speed roughly 80 km/s. For T15 the magnetic field a one- lobe structure was observed similar to that seen in the wake further down Titan's tail during T9[1]. The data are compared with simulation results from a global hybrid plasma model HYB. [1] Sillanpää, I., Hybrid Modelling of Titan's Interaction with the Magnetosphere of Saturn, Ph.D. dissertation, Yliopistopaino, Helsinki, 2008. (Freely available at permalink http://urn.fi/URN:ISBN:978-951- 697-660-3)