DPS 2001 meeting, November 2001
Session 52. Asteroid Discovery and Dynamics I
Oral, Chair: R. Binzel, Saturday, December 1, 2001, 9:40-10:40am, Regency E

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[52.04] Merging, spinning and bouncing in catastrophic collisions: Consequences for final fragment properties

P. Michel (OCA), W. Benz (Berne Univ.), P. Tanga (OCA), D.C. Richardson (Maryland Univ.)

We present new simulations of collisions between asteroids which take into account the production of gravitationally reaccumulated spinning bodies, using a procedure which divides the process into two phases. Using a 3D SPH hydrocode, the fragmentation of the solid target through crack propagation is first computed. Then the simulation of the gravitational evolution and possible reaccumulation of the resulting new fragments is performed using the parallel N-body code pkdgrav. Our first simulations succeeded in reproducing fundamental properties of some well-identified asteroid families. We have now included the possibility of fragments bouncing (instead of strictly merging) when collisions occur at high speed during the gravitational phase. We present comparisons of simulations in three different impact regimes, from highly catastrophic to barely disruptive, using different values of the coefficient of restitution. The largest fragment mass resulting from the reaccumulation of smaller fragments and the ejection velocities of these fragments remain statistically similar for each regime despite the different values of the coefficient of restitution. The final fragment size distribution is also unchanged in the barely disruptive regime, whereas fewer fragments at intermediate sizes seem to be produced at higher impact energy, due to high-speed collisions between fragments during the gravitational phase which prevent merging. Distributions of fragment spins have been analyzed and results are consistent with observations, which supports the idea that disruptive impacts destroy the memory of initial spin. We also observe the natural production of satellite systems around some fragments. We plan to continue our investigations using this procedure and to improve upon the modelling of fundamental physical effects during collisions.

The author(s) of this abstract have provided an email address for comments about the abstract: michel@obs-nice.fr

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