Evolution of planetesimal velocities

Abstract

The velocity evolution of a general planetesimal population is treated by means of a self-consistent set of equations whose form is tailored to those early planetary accumulation stages in which the planetesimal swarm's modeling calls for gas dynamic methods. Dynamical friction is noted to be essential to the transfer of kinetic energy from larger to smaller planetesimals, thereby furnishing an energy source comparable to those furnished by viscous stirring.