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V. Carruba (Cornell University), D. Nesvorny (SwRI), M. Cuk, J. A. Burns, R. Rand (Cornell University)
Carruba et al. (2003) previously studied a layer of chaos for satellites in Kozai resonance, i.e., satellites whose argument of pericenter, instead of circulating from 0 to 360 degrees, librates around ±90 degrees. By performing numerical simulations with test particles covering the orbital space surrounding S/2000S5, a satellite of Saturn currently in this resonance, and by applying the Frequency Analysis Method of Laskar (Laskar, 1993, 1999), we identified a layer of chaos at the transition between circulation and libration.
We now further investigate this chaotic boundary and try to determine its cause(s). Our simulations suggest that, for the case of S5, perturbations from Jupiter are needed to create the chaotic boundary. In order to understand if secular or short-period terms in the disturbing potential of Jupiter are actually responsible for the appearance of the layer of chaos we are performing simulations where test particles are subjected to perturbations from a Jupiter on a fictitious orbit whose parameters are determined using the Bretagnon model (Bretagnon and Francou 1992). By perfoming simulations with Jovian orbits that only include either secular or secular and short-period terms, we are confident we shall be able to identify the source of chaos.
Another problem posed by the existence of the chaotic boundary is its possible relevance for capture mechanisms. In this work we have modified the SWIFT-WHM integrator to account for gas-drag, according to the model of Cuk and Burns (2003). Preliminary results of our simulations suggest that, for typical values of gas density at the mid-point of the disk (6*10-9 g/cm3), the chaotic layer does not affect the capture of satellites into Kozai resonance. The chaotic layer might, however, still play a role in the very last phases of capture, when the gas-disk is dissipating. We are currently investigating different sets of gas-densities and disk parameters.
As Cuk et al. (2002) found, preliminary results of our simulations suggest that at high inclinations satellites under gas-drag tend to be captured into Kozai resonance. We are currently pursuing an analytical model (Beauge' and Ferraz-Mello 1993) to explain this behavior.
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The author(s) of this abstract have provided an email address for comments about the abstract: valerio@astro.cornell.edu
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.