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Chaotic Motions of F-Ring Shepherds

Goldreich, Peter and Rappaport, Nicole (2002) Chaotic Motions of F-Ring Shepherds. . (Submitted) https://resolver.caltech.edu/CaltechAUTHORS:20130228-111724121

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Abstract

Recent HST images of the Saturnian satellites Prometheus and Pandora show that their longitudes deviate from predictions of ephemerides based on Voyager images. Currently Prometheus is lagging and Pandora leading these predictions by somewhat more than 20°. We show that these discrepancies are fully accounted for by gravitational interactions between the two satellites. These peak every 24.8 days at conjunctions and excite chaotic perturbations. The Lyapunov exponent for the Prometheus-Pandora system is of order 0.35 yr^(-1) for satellite masses based on a nominal density of 1.3 gm/cm^(-3). Interactions are strongest when the orbits come closest together. This happens at intervals of 6.2 years when their apses are anti-aligned. In this context we note the sudden changes of opposite signs in the mean motions of Prometheus and Pandora at the end of 2000 occured shortly after their apsidal lines were anti-aligned.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
http://xxx.lanl.gov/abs/astro-ph/0205330arXivUNSPECIFIED
Additional Information:Submitted to Icarus on May 14, 2002 We thank R. French for providing us with a copy his preprint which contains the latest results on the motions of Prometheus and Pandora, and for allowing us to reproduce from it the material in our Fig. 12. We are grateful to R. Jacobson for advice on initializing our integrations in a manner compatible with the Voyager ephemerides. Research by PG was supported by NSF grant AST-0098301 and that by NR by NASA Planetary Geology and Geophysics grant 344-30-53-02.
Funders:
Funding AgencyGrant Number
NSFAST-0098301
NASA Planetary Geology and Geophysics344-30-53-02
Subject Keywords:Satellites of Saturn, Orbits, Chaos
Record Number:CaltechAUTHORS:20130228-111724121
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130228-111724121
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37206
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:11 Apr 2013 23:13
Last Modified:03 Oct 2019 04:45

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