Collisional evolution in the asteroid belt: an observational and numerical study

A major observational survey was conducted to investigate asteroid collisional evolution processes. Photoelectric observations of more than 100 small asteroids were obtained at the University of Texas McDonald Observatory and Cerro Tololo Inter-American Observatory on 150 nights between November, 1982 and February, 1985. These light curve data were used to determine shapes and rotational angular momenta of asteroids in six distinct dynamical regions; near the 3:1 resonance Kirkwood gap, Eos family members, Koronis family members, and three control groups. The survey data were analyzed to shed light on two major outstanding problems in solar system astrophysics: the collisional formation of the Kirkwood gaps and the collisional evolution of the Eos and Koronis families. Near-resonance asteroids show a very similar rotational frequency distribution compared with nonresonance asteroids and the two groups have nearly identical mean light curve amplitudes. An analysis of the locations of asteroid families shows no evidence that resonances increase catastrophic collision probabilities. Therefore it is concluded than inter-asteroid collisions are not an important process in clearing the Kirkwood gaps