Direct simulation of collision processes

Abstract

The mass distribution of protoplanets is studied by a Monte Carlo technique. It is assumed that the bodies coalesce on collision and that their self-gravitation is important. It is found that over most of the mass range a distribution of the formn(m)αm ^−q develops, withq tending to ∼1.8. However, there is an overabundance of large masses relative to the power law: in particular the simulations indicate the growth of a large nucleus which progressively dominates the growth process.

It is also found that the axial inclinations of the planets are best explained if they grew out of a coagulating medium comprising planetesimals with random velocities ∼5 km s⁻¹ and masses up to 10⁻² of the embryo masses. The inclinations of the giant planets are consistent with a floccule-type origin of these bodies.