On the heterogeneous appearance of Saturn's rings at high optical resolution

Abstract

Shoemaker and Terrile have shown that several small satellites can be the parents of Saturn's rings and have suggested these as the origin of the broad systematic differences in the photometric properties of the rings. Dramatic variations on the smallest scales appear in the images obtained from Voyager. The variations of the surface of Enceladus suggest the importance of differentiation of satellites heated by tidal action maintained by resonances, as pointed out by C.M. Yoder. Subsequent break-up of such satellites, either under a large impact or under increasing tidal action of Saturn as its mass increased, would have yielded a mixture of different crustal and interior materials with different spectra of sizes and masses. We shall discuss the possible role of radial differentiation of particles in terms of their masses initiated by the combined activity of instabilities discussed long ago by Maxwell and by Cook and Franklin with those proposed recently by Ward and by Lin and Bodenheimer. In this way, we may reach an explanation of variations on the smallest scales. Comparison will be made with the expected behaviour of a primary accretion disk composed of a uniform distribution of material.