Dynamical injection of Mars-sized planetoids into the asteroidal belt from the terrestrial planetary accretion zone

Abstract

The simultaneous accretion and gravitational scattering of a system of planetoids in the terrestrial planetary region are examined by using a Monte Carlo model. The dynamical consequence of the co-accretion of many large objects of lunar and Martian sizes is investigated with special focus on the possible injection of some of these planetoids into the asteroid belt. It is found that on the average two to three objects of this size range could be scattered into the main-belt region at different time intervals of the accretion process which lasts about a few 10 7 years. Thus the terrestrial zone bodies (TZBs) could help to perturb the original population of asteroids into eccentric orbits. Despite the relatively large orbital scattering of the planetoids by the dominant protoplanets, the resulting compositional mixing scale length has been estimated to be on the order of 0.2 AU. Hence, dynamical study as described here in combination with chemical analysis of planetary samples could be a very powerful tool in deciphering the early process of planetary and asteroidal formation.