Burt, J., Hedman, M. M., Tiscareno, M. S., Burns, J. A. (2008). "The Where And Why Of Saturn's Inclined "Charming Ringlet"" American Astronomical Society, DPS meeting #40, #29.11.


Abstract
The "Charming Ringlet", a dusty ringlet in the outer rift of the Cassini Division, 119,940 km from Saturn's center, appears to be inclined in a series of images captured by the ISS cameras aboard Cassini. The ringlet has been found to be heliotropic - i.e. the geometric center of the ringlet, considered as a whole, is shifted towards the Sun (Hedman et al 2007, DPS). This behavior is likely caused by non-gravitational forces acting on the ringlet's primarily micron-sized particles, as identified by the ringlet's extreme brightening in forward-scattered (high phase angle) images. Under appropriate conditions, solar radiation pressure will cause an individual particle's orbit to reach its maximum eccentricity when its apocenter is aligned with the sun. Through study of the Charming Ringlet's position over a range of viewing geometries we are constraining its vertical structure, namely its orbital inclination, node and the probable causes of such a tilt and seeing if they are consistent with the earlier hypothesis.

We study a series of images, and their associated radial scans, that contain both the Charming Ringlet and a nearby gap edge that is used as a fiducial for navigation. By aligning the gap edge within each image to sub-pixel accuracy, we can very precisely obtain the apparent position of the ringlet. By combining this information with the emission angle at which each image was captured, we will quantify the inclination of the ringlet. We will then study whether this inclination may result from the out-of-plane component of solar radiation pressure, just as the in-plane-component of the radiation pressure is likely responsible for the ringlet's heliotropic behavior.