The atmosphere around Saturn's rings: a study of the probability of collision between ring particles and atmospheric molecules

Abstract

An analytic model is developed to allow deviation of the probability that a molecule in the atmosphere of Saturn's rings collides with at least one ring particle when traversing the ring plane. The resulting expression involves details of the molecule's trajectory, including the velocity of the molecule relative to ring particle; thus, the theory is compatible with recently developed ballistic transport computer models used in the analysis of the rings. The collision theory is applied to a case of a low energy, isotropic molecular production process to make inferences on the spatial extent of the ring atmosphere associated with such a source. The high frequency of collisions expected for the atmosphere in the vicinity of the A and B rings suggests a toroidal atmosphere.