A simulation study of dynamics in the distant Jovian magnetotail

Abstract

In late February 2007, the New Horizons spacecraft flew past Jupiter and repeatedly observed tailward moving plasma structures in Jupiter's distant tail (x > -2000 RJ). There were no solar wind observations in the outer solar system at this time. In this study, we have used a new magnetohydrodynamic model with a 1500 RJ long tail to investigate the propagation of these structures under different solar wind conditions. In the simulation we find that periodic plasmoid ejection from a reconnection line in Jupiter's plasma sheet can occur when the solar wind dynamic pressure is low and the IMF has a northward component along the dipole direction. In particular, periodic plasmoids which are similar to New Horizon observations are reproduced when the interplanetary magnetic field (IMF) was oscillating from northward to southward with a 10 h period similar to what would be expected for a rotating planetary magnetic field interacting with an IMF with only a y component. When the IMF had a southward component along the dipole direction, high-latitude reconnection can form plasmoid-like structures. As a result plasma structures moving tailward can be found over a large region of the tail, as is observed. Oscillations in the solar wind dynamic pressure lead to oscillations in the plasma sheet. Copyright 2010 by the American Geophysical Union.