Modeling the Sources of H2+ and O2+ in Saturn's Magnetosphere

The main rings, the icy satellites and the ice grains in the tenuous rings are all sources of neutral H2 and O2 in Saturn's magnetosphere due to the decomposition of ice (e.g., Johnson et al. 2005, 2006a) and Titan is a source of H2 via atmospheric escape (Yelle et al. 2006). These molecules are eventually ionized contributing the Saturn's trapped plasma. In addition, ion-neutral reactions in the narrow Enceladus neutral torus and the HST torus (Johnson et al. 2006b) can produce molecular hydrogen and oxygen ions and neutrals. Here we calculate the spatial distribution of neutrals ejected from satellites and rings and use these to estimate source rates for H2+ and O2+ for Saturn's magnetosphere. Johnson et al. J. Chem Phys. 123, 184715, 2005a Johnson et al. Icarus 180,393, 2006a Johnson et al. ApJ 644, L137, 2006b Yelle et al. Icarus 182, 567, 2006