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H. Salo, R. Karjalainen (U. Oulu), R.G. French (Wellesley C.), L. Dones (SwRI)
Dynamical N-body simulations suggest the formation of trailing density enhancements in the outer portions of Saturn's rings, due to local gravitational instabilities. These Julian-Toomre type wakes, with pitch angle of about 20-25\circ with respect to the local tangential direction, seem to provide a plausible explanation for the observed quadruple brightness variation in Saturn's A-ring (Salo and Karjalainen 1999, BAAS 31, 1160; French et al. 2000 BAAS 32, 806; Porco et al. 2001, BAAS 33, 1091). We have carried out systematic photometric modeling of gravitational wake structures seen in dynamical simulations, performed for the parameter values of the A-ring. Comparisons to the observed asymmetry in various cases are presented (asymmetry in reflected and transmitted light, ring longitude and opening angle dependence). Implications of wakes on the occultation optical depth profiles and the A-ring overall brightness behavior are also discussed.
This study is supported by the Academy of Finland.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.