Gruen, Eberhard - Dynamical and Collisional Timescales of Meteoroids Released From Jupiter Family Comets

Abstract: 
Large dust particles (meteoroids) released from comets are initially spread along the orbit of their parent body. This spreading is caused by variations in the initial release conditions of the particles, such that they have slightly different orbital periods to their parents. Close planetary encounters (mostly by Jupiter) scatter meteoroids through interplanetary space. Simultaneously collisions with interplanetary meteoroids shatter cometary meteoroids and generate large amounts of smaller fragment particles. An understanding of the importance of these three mechanisms is required to determine how a meteoroid stream disperses into the interplanetary background. To this end, we compare the timescales for spreading, scattering, and shattering of meteoroids released from Jupiter family comet 67P/CG. Jupiter family comets currently provide a major source of meteoroids to the interplanetary complex. Their orbits are characterized by frequent encounters with Jupiter. Comet 67P/CG is a typical member of this class of comets. The initial spreading of meteoroids is calculated by studying the initial velocities of the particles. The effect of Jupiter scattering is simulated on a string of particles along the comet’s orbit. The timescale of planetary scattering is compared to the timescale imposed by the Poynting-Robertson effect. The effects of shattering are determined for meteoroids of masses 10^-6, 10^-3, and 1 g. By applying the ESA IMEM meteoroid model (Dikarev et al., 2005, Advances in Space Research 35:1282) to meteoroid stream particles at various positions along their orbit we calculate their collisional lifetimes, and compare them with timescales for spreading, scattering, and shattering. Our results have implications for the total lifetime of meteoroid stream particles that originate from Jupiter family comets.