Chapter 20. Accumulation Process of Planetesimals to the Planets

Planetesimals born as a result of gravitational instability of the dust layer in the primitive solar nebula suffer successive collisions and accumulate toward the present planets. In this chapter the studies of this accumulation process, mainly numerical simulations performed in the last decade are reviewed. Direct orbital calculation of many-body system and statistical treatment in terms of mass distribution function are the two typical methods of approach. The problems included in these approaches are also discussed.