Orbital Evolution of Retrograde Interplanetary Dust Particles and Their Distribution in the Solar System
The orbital evolution of interplanetary dust particles (IDPs) from both retrograde and prograde Halley-type comets is numerically simulated. It is found that dust particles nearly always get trapped into one or more mean motion resonances (MMRs) with giant planets while in retrograde orbits. Of the 1000 retrograde particles simulated 116 are trapped in MMRs that last longer than 100,000 years, and the MMRs are typically exterior MMRs of the type p:1 with Jupiter where p ranges from 1 to 12. We present a simple analysis of the physical processes involved when an IDP is in a resonance. A quasistable resonance is maintained by the combined effect of the direct perturbation from the planet as well as the indirect perturbation that arises because the Sun is moving around the Sun-planet barycenter. The direct and indirect perturbations are often of comparable magnitudes, although one or the other can be dominant. Of the 1000 retrograde particles simulated, 45 of them evolved to prograde orbits while in MMRs with a giant planet. Although the overall distribution in eccentricity and inclination of 10-7 g dust particles from Halley-type comets is consistent with D. H. Humes' (1980, J. Geophys. Res.85, 5841-5852) interpretation of the Pioneer 10 and 11 data, the spatial density variation is not. Instead of the constant spatial density derived by Humes, the spatial density of Halley-type comet dust varies as r-γ with heliocentric distance r, where γ ranges from 1.5 to 1.8. Additional sources of interplanetary dust particles are needed to account for the discrepancy.