Cassini Imaging of Saturn's Huygens Ringlet
Abstract
We present the results of an examination of Saturn's Huygens ringlet, 250 km exterior to the B-ring, based on ISS observations spanning an eight-year interval from 2005 -- 2013. The Huygens ringlet is a narrow eccentric ringlet in the classical shape of a ~28-km amplitude Keplerian ellipse with the apses of the inner and outer edges nearly locked. However, unlike most narrow eccentric ringlets, the Huygens ringlet has a nearly uniform width at all longitudes, which is inconsistent with the classical theory for gravitating ringlets, so new ringlet physics is implicated. The Keplerian shape is perturbed by higher-order structure with amplitudes in the 1--2-km range. The outer edge shows two superimposed m=2 patterns, one moving at Mimas's rate, implying that it is forced by the nearby 2:1 Lindblad resonance, and the other moving at a rate consistent with a free normal mode. The forced and free m=2 modes on the outer edge have amplitudes of about 1 and 2.3 km respectively. The inner edge shows a single m=2 pattern forced by the Mimas resonance, with an amplitude of about 2 km. Patterns with higher wavenumbers appear in individual data sets and do not appear to be long-lasting. Additional stochastic structure is prevalent in the ringlet and cannot be modeled using a simple superposition of low-wavenumber Fourier modes. The stochastic structure may reflect gravitational unevenness within the ring, and the the higher-order transient normal modes may be a response to stochastic perturbations arising from those clumps.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #45
- Pub Date:
- October 2013
- Bibcode:
- 2013DPS....4520610S