Discontinuities in the Magnetic Field near Enceladus

Wednesday, 17 December 2014: 3:25 PM
Sven Simon1,2, Joachim Saur1, Shari van Treeck1, Hendrik Kriegel3 and Michele Karen Dougherty4, (1)University of Cologne, Cologne, Germany, (2)Georgia Institute of Technology, Atlanta, United States, (3)TU Braunschweig, Braunschweig, Germany, (4)Imperial College London, Blackett Laboratory, London, United Kingdom
The plasma interaction of Saturn's icy moon Enceladus generates a hemisphere coupling current system that directly connects the giant planet's northern and southern polar magnetosphere. Based on Cassini magnetometer observations from all 20 targeted Enceladus flybys between 2004 and 2014, we study the magnetic field discontinuities associated with these hemisphere coupling currents. We identify a total number of 11 events during which the magnetic field was discontinuous at the surface of the Enceladus fluxtube (defined by the bundle of magnetic field lines tangential to the solid body of the moon). A Minimum Variance Analysis is applied to calculate the surface normals of these discontinuities. In agreement with theoretical expectations, the normals are found to be perpendicular to the surface of the Enceladus fluxtube. The variation of the hemisphere coupling currents with Enceladean longitude leaves a clear imprint in the strengths of the observed magnetic field jumps as well.