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A. Moro-Martin (Steward Observatory, University of Arizona), R. Malhotra (Department of Planetary Sciences, University of Arizona)
The dust produced in the Kuiper Belt (KB) spreads throughout the Solar System forming a dust disk. We have numerically modelled the dynamical evolution of KB dust grains using a modified symplectic integrator which resolves close planetary encounters and includes solar wind and radiation forces. We report here a selection of results from our modeling efforts. (1) We find that the particle size frequency distribution of KB dust is greatly changed from its distribution at production, due to the combined effects of radiation forces and the perturbations of the planets. In particular, the gravitational scattering of dust by the giant planets is able to extend the dust disk beyond the boundaries set by radiation effects alone, and consequently, the size distribution is greatly different at large distances. We plan to investigate the potential of this effect for the detection of planets in debris disks. We also point out that the detection of circumstellar dust disks of wide radial extent, 100 to 1000's of AU, does not necessarily imply the presence of dust-producing planetesimals at such large distances, because the presence of giant planets at much smaller semimajor axes can lead to the spreading of the dust to distances much larger than the aphelion of the parent bodies. (2) We have estimated the contribution of KB dust to the population of IDPs collected at Earth, by calculating geocentric encountering velocities and capture rates. Our models show, in contrast with previous studies, that KB dust grains on Earth-crossing orbits have high eccentricities and inclinations, and therefore their encountering velocities are similar to cometary grains and not to asteroidal grains. We estimate that at most 25% of captured IDPs have cometary or KB origin. Using the Kuiper Belt dust production rates derived from detectors on board Pioneer 10 and 11 spacecraft (Landgraf et al. 2002), we find that presently the KB contribution may be as low as 1-2%. (3) We have calculated the velocity field of KB dust throughout the Solar System; this, together with the number density radial profile, is potentially useful for designing dust detection instruments for future spacecraft missions, as well as for estimating the hazard to space probes in the outer Solar System.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.