Host: The Japanese Society for Planetary Sciences: Local Organizing Committee for 2007 Fall Meeting
In the last stage of the terrestrial planet formation, several giant impacts occur. Although the nature of giant impacts determines the final state of the terrestrial planets (number, mass, spin etc), all the previous N-body simulation of terrestrial planet formation have been based on the assumption of the perfect accretion. Agnor and Asphaug (2004) performed 48 SPH simulations for mutual collision of Mars-mass planets. They showed that the two protoplanets bounce and escape to infinity for collision with relatively faster impact velocity, and they estimated that more than roughly half of giant impact events are not coalescence events.To incorporate the effect of imperfect accretion into N-body simulations, we need to know the accretion condition for various types of giant impacts. Using the special purpose computers named micro-GRAPE6, we performed more than 1000 runs of impact SPH simulations. We formulated the boundary between coalition and rebound. We also formulated the mass(es) and orbit(s) of post-impact planet(s). We applied the above formulation to the impact events obtained by Kokubo et al. (2006), and 41% of giant impacts are not coalescence events.
