The mass distribution of an accreting system of dust particles - a Monte Carlo simulation

Accretion is obviously a dominant process in the formation of many astronomical objects. In this paper an accretion process is simulated by assuming that initially all the particles have the same mass and that low velocity collisions result inevitably in the two colliding particles sticking together. Particle disruption is not considered. Results are presented showing how the mass distribution index, s, of the resulting collection of particles varies both as a function of particle mass and also collision number. Two cases are considered, firstly where the total number of unit mass particles present remains constant and secondly where the total mass of material remains constant. The first case leads to a constant s-value of 1.65 +- 0.11 the second case to an s-value which drops below 1.33. (author)