Stirring and dynamical friction rates of planetesimals in the solar gravitational field

The present investigation of the eccentricity and inclination variations due to mutual gravitational scattering that are responsible for random velocity changes in planetesimals takes the solar gravitational field into account. A three-body formalism integrated through 10-100 million three-body orbital integrations is used to present viscous stirring and dynamical friction rates. It is found that, in the low-energy cases dominated by Keplerian shear, eccentricity grows substantially more rapidly than inclination, while dynamical fraction, by contrast, is not effective. In the high-energy cases dominated by random motion, a 2:1 eccentricity/inclination ratio is reached spontaneously. 16 refs