Prometheus and the Keeler gap
Abstract
Linblad resonances with Saturn’s satellites are located at many radii in the rings. While some cause density or bending waves, others hold gap edges from spreading, like the 2:1 resonance with Mimas located at the B-ring edge, the 7:6 resonance with Janus at the A-ring edge, and the 32:31 resonance with Prometheus at the inner edge of the Keeler gap. The latter is the case of study here.Theoretically, the inner edge of the Keeler gap should have 32 regular sinusoidal lobes, where either the maximum or the minimum radius is expected to be aligned with Prometheus and rotating with its mean motion. We show that such is not the case. Fit of occultation data shows the presence of the 32:31 resonance, however, the fit residuals is as high as the amplitude of the resonance amplitude (about 2 km). Analysis of the ISS data, shows irregularities overlapping the lobes (Tiscareno et al. 2005, DPS), that follow Keplerian motion. These irregularities may be due to clumps of particles with different eccentricities than the rest of the edge particles. This phenomenon may be caused by the resonance, as it has not been observed at other circular edges were no resonance is present at their location. The ISS data also shows that the lobe’s minimum/maximum is not perfectly aligned with the longitude of Prometheus, which may be due to libration about the centre of the resonance.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #46
- Pub Date:
- November 2014
- Bibcode:
- 2014DPS....4640205T