Radial widths, optical depths, and eccentricities of the Uranian rings

Abstract

Observations of the stellar occultation by the Uranian rings of 15/16 August 1980 are used to estimate radial widths and normal optical depths for segments of rings 6, 5, 4, ɑ, β, η, y, and δ. Synthetic occultation profiles are generated to match the observed light curves. A review of published data confirms the existence of width-radius relations for rings ɑ and β, and indicates that the optical depths of these two rings vary inversely with their radial widths. Masses are obtained for rings ɑ and β, on the assumption that differential precession is prevented by their self-gravity. A quantitative comparison of seven є-ring occultation profiles obtained over a period of 3.4 yr reveals a consistent structure, which may reflect the presence of unresolved gaps and subrings. Elliptical models for rings 6, 5, 4, ɑ, β, and є are presented for comparison with the results of previous studies, particularly that of Elliot et al. (1981a).