On planetary rings as sources and sinks of magnetospheric plasmas

Abstract

ABSTRACTThe presence of satellite and ring systems in the magnetospheres of Jupiter, Saturn and Uranus introduces interesting new physical effects affecting the general dynamics and compositions of these magnetospheres. Besides acting as a sink for the magnetospheric particles via solid-body absorption, the satellites and rings could also emit neutral and ionized gas into the magnetospheres. In the case of the Saturnian rings, because of their especially broad structure and close proximity to the planet, strong exospheric and ionospheric couplings can also take place. Several observed features (e.g. depletion of the ionospheric electron content, generation of the atomic hydrogen cloud in the vicinity of the rings, and a discontinuity in optical depth at 1.64 Rsin the B ring) of the ionosphere and the ring system could result from the related processes of mass transport and exchange between the ionosphere and the rings. Similar effects may also occur in the region of the tenuous E ring leading to peculiar equatorial confinement of the corotating thermal plasma there.