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Published September 16, 1982 | public
Journal Article

Sharp edges of planetary rings

Abstract

The ring systems of Saturn and Uranus exhibit several sharp edges across which the optical depth drops from order unity to essentially zero. At least two and perhaps all of these features are associated with the location of orbital resonances between a satellite and the ring particles. It is remarkable that the optical depth varies on a distance scale which is much finer than that over which angular momentum can be transferred between a satellite and the ring material. The important features of this phenomenon are: (1) A perturbed band of width Δa/a ≃ (M_s/M_p)^(½) adjacent to the edge within which the angular momentum transfer occurs. (2) Streamlines perturbed such that the angular momentum luminosity decreases smoothly across the band to zero at the edge even though the optical depth remains constant. (3) Dynamical equilibrium requires a relation between the random velocity, the rate of deformation and the optical depth.

Additional Information

© 1982 Nature Publishing Group. Received 23 June; accepted 29 July 1982. We thank E. Danielson, A. Lane, J. Lissauer, R. Terrile and L. Tyler for helpful discussions. During this research N.B. held a NSF US-France exchange postdoctoral fellowship and a grant from ATP Planétologie 1981. P.G. acknowledges support from NSF grant AST 80-20005 and NASA grant NGL-05-002-003. S.T. acknowledges support from NASA grants NSG-7643 and NGL-22-009-638. This work is contribution 3797 from the Division of Geological and Planetary Sciences, California Institute of Technology.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023