Comets as a source of low eccentricity and low inclination interplanetary dust particles

In the all sky survey by the Infrared Astronomical Satellite in 1983, eight comets were discovered to have dust trails (Sykes, M. V., and R. G. Walker 1992. Icarus 95, 180-210). Among those eight comets, the most prominent trail belonged to Tempel 2, suggesting that this comet recently has been the most prolific producer of interplanetary dust. A numerical simulation of the orbital evolution of 4- and 9-mu m diameter dust particles from Tempel 2 shows that radiation pressure causes a significant fraction of dust particles in this size range to be directly injected into a 1:2 interior mean motion resonance with Jupiter. There, they remain trapped for thousands of years. When they escape the resonance, their orbital eccentricities are quite small. These, and dust grains from other similar Tempel-type comets, approach the Earth with the low velocities typical of asteroidal dust grains. Many dust particles collected from the stratosphere have been shown to have undergone little heating upon entry into the Earth's atmosphere and were assigned an asteroidal origin on this basis. This includes a sub-group, the chondritic porous aggregates. Our new analysis shows, however, that it is quite possible that this sub-group of grains derive from Tempel-type comets, and not from asteroids. (C) 1996 Academic Press,Inc.