Dynamical evolution of interplanetary dust particles

We study the orbital evolution of dust particles in the region of exterior mean motion resonances with the Earth. The trajectories of the particles are integrated in the context of a seven-body problem (Sun, five major perturbating planets and the particle) with the solar radiation and wind forces accounted for. Regions of stable resonant trapping are identified in the e-(omega-tilda) plane for a sequence of first order j/(j+1) resonances. On the basis of these maps it comes out that particles reaching the proximity of the Earth with high values of eccentricity are trapped more frequently in low-j resonances. Results for different particle sizes are presented. We have also integrated the orbits of particles for more than 105 yr by a procedure alternative to the direct integration of the many-body problem, i.e. by introducing directly in the equation of motion the position vectors of the planets as obtained from the recent Richardson & Walker (1989) accurate numerical simulation of the full planetary system. A study of the trapping times has been performed for different j/(j+1) resonances for different particle sizes. The duration of the trapping phenomenon is regulated by occurrence of close approaches with the Earth. For the 2/3 and 3/4 resonances, close approaches to Mars can also be important in forcing the particle out of resonance.