The Triton torus revisited

Prior to the Voyager encounter with Neptune, Delitsky et al. [1989] predicted that a torus of ions emanating from Triton would be discovered. The authors revisit those predictions in light of the Voyager results. Sputtering of Triton's atmosphere can produce the heavy ion densities inferred at Triton's orbit by the Voyager plasma experiment if the ion residence time is about 30 days. The torus is found to be longitudinally asymmetric near Triton, with peak densities at longitudes of 170 degree and 350 degree. The total nitrogen flux due to sputtering is about 2x1021 s-1. The consequences of larger escape fluxes of both N2 and H2 (suggested by Broadfoot et al. [1989]) are investigated; it is difficult to reconcile large escape fluxes with the plasma and ultraviolet spectrometer observations