Orbital Evolution of the Dust Streams Released from Comets

The results of the study of the orbital evolution of cometary dust grains with characteristic sizes of 1 to 100 microns may be summarized in the following five conclusions. (1) There is no definite cut-off of particle sizes by direct solar radiation pressure even for a system of particles released from the same parent body. (2) The broad range of the escape limit for eccentric cometary orbits makes the mass distribution function of the released dust significantly deviate from that of the original partition. (3) Very short Poynting-Robertson lifetimes are virtually impossible since the Poynting-Robertson spiralling must begin from a strong orbit enlarged by direct radiation pressure. (4) Progressive fragmentation and erosion reinforces the effect of direct radiation pressure which counters the Poynting-Robertson drag. (5) A prolongation of the dynamic lifetime by radiation pressure applied at the time of separation from the parent body, and at the time of subsequent reduction of the particle size, tends to increase the dispersive effects of planetary perturbations.