Evolution of Planetesimals. I. Dynamics: Relaxation in a Thin Disk
Abstract
The study examines the effects of density inhomogeneity and differential rotation as well as inelastic collisions on the dynamical evolution of planetesimals. Consideration is given to a threestep analysis: the dynamical evolution of the planetesimals, collisions and mass accumulation, and interaction with gas. It is shown that the velocity dispersion of a cold system of planetesimals increases rapidly due to elastic gravitational scattering. When the dispersion in the epicycle amplitude becomes comparable to the planetesimals' Roche radius, energy is transferred from the systematic Keplerian shear to the dispersive motion. With a numerical Nbody scheme, gravitational scattering and physical collisions among a system of planetesimals is simulated. It is shown that dynamical equilibrium is attained with a velocity dispersion comparable to the surface escape velocity of those planetesimals which contribute most of the system mass.
 Publication:

The Astrophysical Journal
 Pub Date:
 January 1993
 DOI:
 10.1086/172207
 Bibcode:
 1993ApJ...403..336P
 Keywords:

 Computational Astrophysics;
 Planetary Evolution;
 Protoplanets;
 Solar System Evolution;
 FokkerPlanck Equation;
 Gravitational Effects;
 Orbital Elements;
 Planetary Orbits;
 PLANETS;
 PLANETESIMALS;
 SOLAR SYSTEM;
 DYNAMICS;
 ENERGY;
 SCATTERING;
 COLLISIONS;
 EQUILIBRIUM;
 PLANETARY SYSTEMS;
 ORBITAL ELEMENTS;
 ORIGIN;
 MODEL;
 DIFFUSION;
 PARAMETERS;
 GRAVITY EFFECTS;
 DISKS;
 CALCULATIONS;
 ANALYSIS;
 ORBITS;
 MOTION;
 CELESTIAL MECHANICS;
 VELOCITY;
 DAMPING;
 RELAXATION;
 FRICTION;
 MASS;
 ACCRETION;
 THEORETICAL STUDIES;
 COAGULATION;
 FORMATION;
 Lunar and Planetary Exploration; Planets;
 HYDRODYNAMICS;
 SOLAR SYSTEM: FORMATION;
 STARS: PLANETARY SYSTEMS