Unusually strong magnetic fields in Titan's ionosphere: T42 analysis

The observations of unusually large magnetic fields indicate periods of greatest stress on Titan's ionosphere and potentially of strongest loss rate of ionospheric plasma. During Titan flyby T42, the observed magnetic field maximized at 37 nT between an altitude of 1200 and 1600 km, over 20 nT stronger than previous measurements and close to five times greater in pressure. The strong fields occurred near the corotation- flow terminator rather than at the sub-flow point, suggesting that the flow that magnetized the ionosphere can be from a direction far from corotation. Extrapolation of solar wind plasma condition from Earth to Saturn using the UMich MHD predicts an enhanced solar wind dynamic pressure at Saturn close to this time. Earlier exits of Cassini from the magnetosphere support this prediction and the CAPS instrument saw a magnetopause crossing three hours before the strong-field observation. Thus it appears that Titan was magnetized when enhanced dynamic pressure compressed the magnetosphere and perhaps the magnetosheath magnetic field in onto Titan. The solar wind then relaxed leaving a strong fossil field in the ionosphere. When observed this strong magnetic flux tube had begun to twist further enhancing its strength. In this paper we examine the forces and stability of this structure, its possible source and its possible affects on the ionosphere.