DPS Pasadena Meeting 2000, 23-27 October 2000
Session 52. Solar System Origin I
Oral, Chairs: R. Canup, D. Trilling, Friday, 2000/10/27, 10:30am-12:10pm, Little Theater (C107)

[Previous] | [Session 52] | [Next]

[52.04] Collisional evolution of a planetesimal disc close to a giant planet embryo

S. Charnoz, A. Brahic, P. Thébault (Gamma-Gravitation, Université Paris VII, CEA, France)

In order to understand if the dynamical evolution of a disc of planetesimals may be modified by the presence of a giant planet embryo, simple dynamical models have been studied. We present here the evolution of a disc of few thousands particles orbiting in the potential field of a central body and perturbed by a 5 to 30 Earth's masses embryo. Physical collisions between particles have been considered while gravitational encounters have been neglected. Initial conditions correspond to a cold unperturbed disc of particles where relative velocities are of the order of 10 m/s. Particles initially between one and few Hill radii from the perturber's orbit are put on very eccentric orbits and relative velocities become of the order of 1000 m/s, well beyond the escape velocity of planetesimals. Due to successive violent collisions between particles, the perturbation propagates far away from the perturber, like a heat transfer. A 30 Earth's masses perturber orbiting at 5.2 u.a is able to heat the disk in a region extending from 1.7 a.u to 10 a.u in few 100 000 years. In the perturbed region, a radial mixing and transport of material occur and relative velocities are 100 to 1000 m/s. In few million years, the loss of energy due to collisions cools down the disc. As a function of the perturber's mass, two different cooling regimes appear. For a massive embryo, perturbations are strong but the associated time scales are rather short, while smaller perturbations appear for a small mass perturber, but for a much longer time scale. Potential applications concerning the origin of the asteroid belt are presented. The possible role of fragmentation is also discussed.

The author(s) of this abstract have provided an email address for comments about the abstract: charnoz@cea.fr

[Previous] | [Session 52] | [Next]