The size-frequency distribution of the zodiacal cloud: Evidence from the solar system dust bands

Recent observations of the size-frequency distribution of zodiacal cloud pa rticles obtained from the cratering record on the LDEF satellite are the la test evidence for a significant large particle population (100-mum diameter or greater) near 1 AU. Our previous modeling of the Solar System dust band s, features of the zodiacal cloud associated with the comminution of Hiraya ma family asteroids, has been limited by the fact that only small particles (25-mum diameter or smaller) have been considered. This was due to the pro hibitively large amount of computing power required to numerically analyze the dynamics of larger particles. The recent availability of inexpensive, f ast processors has finally made this work possible. Models of the dust band s are created, built from individual dust particle orbits, taking into acco unt a size-frequency distribution of the material and the dynamical history of the constituent particles. These models are able to match both the shap es and amplitudes of the dust band structures observed by IRAS in multiple wavebands. The size-frequency index, q, that best matches the observations is approximately 1.4, a distribution in which the surface area (and hence t he infrared emission) is dominated by large particles. However, in order to successfully model the "ten degree" band, which is usually associated with collisional activity within the Eos family, we find that the mean proper i nclination of the dust particle orbits has to be approximately 9.35 degrees , significantly different from the mean proper inclination of the Eos famil y (10.08 degrees). (C) 2001 Academic Press.