[Previous] | [Session 15] | [Next]
D. E. Dunn (University of Iowa), L. A. Molnar (Calvin College), J. D. Fix (University of Iowa)
We present final brightness maps of Saturn's rings as observed at two epochs with the Very Large Array. The first epoch was 20 November 1995 during the Saturnian autumnal equinox. We observed at 0.7, 2.0, 3.6, and 6.1 cm wavelength. The ring inclination was +2.7 deg. The rings show the western ansa brighter than the eastern ansa, especially at the longer wavelengths. The second epoch was in February 1997 and we observed at 1.3, 2.0, 3.6, 6.1, 18, and 21 cm. The ring inclination at this time was -5 deg. At this moderate inclination the rings show no such asymmetry. Asymmetry like this has been seen before by de Pater and Dickel [Icarus 94, 474 (1991)] at yet higher (> 20 deg.) inclinations.
Neither the asymmetry nor its dependence on inclination angle can be explained in terms of a single scattering process. As we previously suggested, this effect may be caused by multiple scattering in an anisotropic particle distribution, such as a gravitational wake. In this presentation we show preliminary Monte Carlo simulations of the radiative transfer onto a finite layer of scatters. We vary parameters such as particle albedo, index of refraction, particle size distribution, and spatial distrubution of particles (i.e. wakes) to determine the source of the brightness temperature found in the rings.