Hahn, J.M., Spitale, J.N., Porco, C.C. (2008). "The Physics of the Sharp Edges of Broad Planetary Rings." American Astronomical Society, DDA meeting #39, #18.04.

The outer edge of Saturn's main B ring is maintained by an m=2 inner Lindblad resonance (ILR) with the satellite Mimas, while the outer edge of Saturn's A ring is preserved by an m=7 ILR with the Janus/Epimetheus coorbital pair. These satellites' resonant perturbations excite an m-lobed disturbance at a ring's edge whose amplitude, we find, is quite sensitive to the ring's physical properties, namely, its surface density and the pressure that is a consequence of collisions among ring particles. In order to better understand these perturbed ring-edges, we have developed a nonlinear model of these resonant ring-satellite interactions, one that also accounts for the ring's internal forces, namely, ring self-gravity, pressure, and viscosity. This talk will assess the relative importance of these internal forces, and will illustrate how the ring's radial excursions and surface density variations all depend on the rings' properties. This model can then be used to diagnose the physical properties of Saturn's main rings by comparing Cassini observations to simulations of these ring edges (Spitale et al., this conference).