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M. Seiss, J. Schmidt (University of Potsdam, Germany), H. Salo (University of Oulu, Finland), F. Spahn (University of Potsdam, Germany), M. Sremcevic (University of Colorado, Boulder, USA)
We used the method of local box simulations to investigate the density perturbationsin a planetary ring as a consequence of the presence of an embedded small moonlet.We verified the formation of a S-shaped density structure (propeller interfered with wakes) predicted by Spahn and Sremcevic, Astron. Astrophys. 358 (2000), 368, and Sremcevic et al. MNRAS 337 (2002), 1139, which scales in radial direction with the Hill radius and in azimuthal direction with the mass of the satellite over the viscosity of the ring material. The "propeller" is adorned with density wakes leading as well as trailing the moonlet.
The results may be used to detect small embedded satellites in Saturn's rings in the Cassini imaging data (ISS) and in the occultations carried out by the ultra-violet-spectrometer Cassini (UVIS). Some density features described with our modeling have recently been confirmed with the Cassini-ISS cameras which uncovered a satellite of about 7 kilometer in diameter (S/2005 S1) revolving in the Keeler gap. Additionally, this example affirms fairly well the radial scaling of the Keeler gap predicted by the theory.
In case of a detection of further embedded bodies the theoretical scalings enable estimates for their mass as well as for the viscosity of the surrounding ring material. Further detections of moonlets might provide implications for an origin of Saturn's rings by a catastrophic disruption of parent bodies.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.