Characterization of Small Gaps in Saturn's Rings from Skewness of Stellar Occultation Data
Abstract
The Cassini Ultraviolet Imaging Spectrograph (UVIS) high-speed photometer (HSP) collected stellar occultation data from stars of various brightnesses as they were occulted by Saturn's rings over a range of viewing geometries. We calculate the skewness of the occultation data and analyze these statistics as a function of optical depth, ring plane radius, and bin size. We use Monte-Carlo simulations of a simplified ring system composed of identical spherical particles interspersed with small gaps ("ghosts") and clumps to determine their effects on skewness. When only ghosts are present, we find that the skewness of the simulated data achieves its maximum when the size of a single measurement matches the largest ghost size. Similarly, when only clumps are present, the simulated data achieves its minimum skewness when the size of a single measurement is equivalent to the size of largest clump. By binning the data and by comparing occultations with different spatial resolutions we are able to probe the data to determine the characteristics of the size distribution of ghosts in the rings. We compare these results to the data in regions where ghosts exist, such as the plateaus in the C Ring (Baillie et al. 2013, Astron. J., 145, 171). We find that the largest ghosts in the C ring plateaus are ~30 m in radial extent, broadly consistent with Baillie et al (2013). The current analysis does not rely on detection of individual statistically significant ghost features and is therefore a broader measure of the distribution of gap sizes in the rings. We present our results combining analysis of multiple occultations with comparisons of simulations using various ghost size distributions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP017...02G
- Keywords:
-
- 2442 Meteor-trail physics;
- IONOSPHERE;
- 6015 Dust;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 5759 Rings and dust;
- PLANETARY SCIENCES: FLUID PLANETS;
- 6213 Dust;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS