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D. C. Richardson (University of Maryland)
Recent ground-based and spacecraft observations of asteroids have revealed the existence of nearly a dozen asteroid satellites among the near-Earth and main-belt populations. Favorable suggested methods of satellite formation include: 1) tidal splitting during a close encounter with a planet; and 2) formation via collision either by retention in orbit of post-collision ejecta around the largest remnant or by mutual capture of escaping fragments. Direct numerical simulations that include both collisional physics and gravity are just now beginning to explore these possibilities. Previous work on tidal splitting either used an idealized two-particle model of the progenitor or were designed to explore issues other than satellite formation. In the present study, results from a simulation of the tidal disruption of a km-sized gravitational aggregate by the Earth show in unprecedented detail the formation of a binary with mass ratio 2.8:1 in an orbit of initial eccentricity 0.16 and semi-major axis equal to 2.3 times the sum of the component mean radii. The larger component is ellipsoidal with an aspect ratio of 2.0:1.1:1.0 (similar in shape to the progenitor) while the smaller component is nearly spherical. The secular evolution and long-term stability of this system are discussed. Results are compared with analytical solutions of the general equations for dynamical evolution of mutually orbiting non-spherical bodies.
The author(s) of this abstract have provided an email address for comments about the abstract: dcr@astro.umd.edu