Collisional evolution of the outer asteroid belt

We present numerical results obtained by simulations of the collisional process between outer belt asteroids and scattered planetesimals from the Uranus-Neptune zone during their accretion period. We obtained final size distributions for the Hildas dominated by the collisional process with planetesimals, and as a consequence of this result, the observed population appears to be complete or nearly complete at sizes greater than or equal to 10 km in radius. In the proposed scenario, the elongated shapes of the largest Hildas should not be the result of a collisional process but could be primordial. The results obtained for the Trojan asteroids, for different initial masses, show that the final size distribution is dominated by the cometesimal bombardment, but in opposition to the Hilda asteroids, the observed size distribution appears to be incomplete for r < 30 km. These results make it possible to assume that the initial mass of the asteroid belt was 4-6 times that at present. (C) 2000 Academic Press.