Observable implications of tearing-mode instability in Jupiter's nightside magnetosphere

Abstract

We consider the implications on observations of tearing-mode instability in Jupiter's nightside magnetosphere. Theoretical developments of the tearing instability are briefly discussed. Using a self-consistent axisymmetric magnetic field model based on the Voyager data, it is found that magnetic reconnection driven by the internal magnetospheric energy and plasma can occur in the nightside magnetosphere. Particles accelerated at the neutral Line, with maximum energy of the order of 10 MeV, are to be expected on the separatrix magnetic surface, which crosses the equatorial plane at a nightside distance of about 60 Jovian radii. When mapped onto the polar regions, this corresponds to magnetic latitudes near to 73°, so that the associated auroral emission should be located well inside the Io torus footprint. Also radio emission from the streaming electrons can be expected. Recent Ulysses as well as ground-based observations support this scenario.