Limitations to the transfer of angular momentum in Saturn's middle magnetosphere

Dr. Licia Ray

Space and Atmospheric Physics Group, The Blackett Laboratory, Imperial College London

The Saturnian magnetosphere is a rapidly rotating system populated with neutral gas from Enceladus.  Neutrals are ionized and picked-up by the planetary magnetic field and, outside of 6 Rs radially transported outwards through the magnetosphere.  Field aligned currents couple the magnetospheric plasma to the ionosphere, transferring angular momentum to the magnetospheric plasma.  These upward currents are responsible for infrared, visible, and ultraviolet auroral emissions in Saturn’s atmosphere.  However, the magnetospheric plasma lags the planetary corotation rate by 20% indicating that there exists a limitation to the transfer of angular momentum from Saturn to its magnetospheric plasma.  We present possible limitations to the field-aligned current density and explore how they affect the radial transport and local pick-up of plasma in the Saturnian magnetosphere.  We also compare modeled energy fluxes to those derived from auroral observations at Saturn.

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