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C. J. Mitchell, J. E. Colwell, M. Horanyi (Laboratory for Atmospheric and Space Physics)
We examine the capture of interplanetary dust particles by Saturn using both a simple two-dimensional code as well as a three-dimensional code with a more detailed magnetosphere. Earlier work on capture at Jupiter has shown that a preference for retrograde captures exists. Here we use our simplified two dimensional numerical integrations to demonstrate that retrograde captures are more likely due to the greater range of the Jacobi constant available for retrograde orbits once they have circularized.
We use the three dimensional code to calculate the probability for dust to be caught from the interplanetary dust population as a function of grain size. These interplanetary dust particles have small eccentricities and inclinations. The initial conditions for the three-dimensional code are chosen from those interplanetary grains which come within 50 Saturn Radii during their orbit about the sun.
Integrations over short time scales show that the ratio of retrograde to prograde captured particles is around 3.5:1, with the largest number of particles captured for grain radii of about 100 nm. The capture efficiency for particles with sizes between 5 and 300 nm is about 0.5 %. Long term integrations are used to calculate the equilibrium dust distribution orbiting Saturn. We will make model predictions that will be verified by the upcoming Cassini in situ dust measurements.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.