Eccentric features in Saturn's outer C ring
Abstract
A systematic search has been made for as yet unrecognized eccentric and inclined features in Saturn's outer C ring. The radii of all sharp-edged features in the outer C ring were measured in Voyager data consisting of six high-resolution images, the Photopolarimeter occultation data, and the Radio Science λ3.6-cm occultation data corrected for the effects of diffraction. Besides the well-known Maxwell ringlet at 87,491 km (1.450 Rs), whose eccentric shape and kinematics have already been studied, two other narrow ringlets at 88,716 km (1.470 RS), and 90,171 km (1.495 RS) have been found to be demonstrably eccentric. The former has a mean width of ∼16 km and is located within a gap ∼30 km wide. The latter has a mean width of ∼62 km and is only partially isolated: its outer edge is defined by a gap ∼15 km wide. Though a coincidence of these two gaps with the Mimas 3:1 inner vertical and inner Lindblad resonances has been noted by previous workers, we find that neither ringlet shows conclusive evidence for the anticipated resonantly forced distortions. The 1.495 RS ringlet is best fitted by a model describing a freely precessing Keplerian ellipse with a radial amplitude of 2.8 ± 0.5 km. Neither a resonant forcing nor a free precession model fitted to the 1.470 RS ringlet provides conclusive results, though the latter is marginally better, yielding an amplitude no larger than ∼2.2 km. These two newly identified eccentric ringlets are compared with the previously studied Titan and Maxwell ringlets (C. Porco, P. D. Nicholson, N. Borderies, G. E. Danielson, P. Goldreich, J. B. Holberg, and A. L. Lane, Icarus 60 (1984), 1-16) and with the Uranian α, β, and ɛ ring.
- Publication:
-
Icarus
- Pub Date:
- November 1987
- DOI:
- 10.1016/0019-1035(87)90185-0
- Bibcode:
- 1987Icar...72..437P
- Keywords:
-
- Planetology;
- Saturn Rings;
- Collisions;
- Occultation;
- Polarimeters;
- Resonance;
- Voyager 1 Spacecraft;
- Voyager 2 Spacecraft;
- SATURN;
- RINGS;
- C RING;
- FEATURES;
- ECCENTRICITY;
- INCLINATION;
- RADIUS;
- SPACECRAFT OBSERVATIONS;
- VOYAGER MISSIONS;
- RINGLETS;
- PHYSICAL PROPERTIES;
- WIDTH;
- GAPS;
- RESONANCE;
- MODELS;
- AMPLITUDE;
- ISS INSTRUMENT;
- DEPTH;
- PPS INSTRUMENT;
- PHOTOPOLARIMETRY;
- RSS INSTRUMENT;
- OPTICAL PROPERTIES;
- PERTURBATIONS;
- CALCULATIONS;
- GRAVITY EFFECTS;
- PARAMETERS;
- COLLISIONS;
- SATELLITES;
- MIMAS;
- PANDORA;
- PROMETHEUS;
- SHAPE;
- COMPARISONS;
- PATTERNS;
- Lunar and Planetary Exploration; Saturn, Earth Science