Spitale, J. N., Porco, C.C. (2007). "Small-Scale Longitudinal Striations in Saturn's C-Ring Plateaus." American Astronomical Society, DPS meeting #39, #26.03.


Abstract
Cassini ISS images taken over the past year have shown striations in three of the prominent optical depth "plateaus" in Saturn's C ring. The striations consist of brightness variations in the NAC clear filters of about 1% that are typically several km wide and tens of km long, aligned along the orbital direction. Of the six most prominent plateaus, all of which were well sampled, the striations appear only in those centered at 84850, 86500, 89900 km from Saturn. The striations occupy the entire radial width of each plateau and show no significant variation with co-orbital longitude throughout several ansa-staring movies. They are seen at a variety of phase and emission angles, but appear only in images taken since late 2006. Indeed, they appear in nearly every such image with a radial scale better than 3 km/pixel. Although those images tend to have higher resolutions than the earlier images, many earlier images do have adequate resolution to observe the striations and yet they are not seen. The solar elevation has been steadily decreasing and the images showing the striations occur at solar elevations of 16 degrees or lower from the ringplane. No correlation with solar azimuth (the angle between the direction to the sun and the direction to the planet at the ring aimpoint) has been observed. This presentation will present the detailed imaging results on these features and possible explanations for their origins.