NUMERICAL SIMULATIONS OF PARTICLE ORBITS AROUND 2060-CHIRON

Scattered light from orbiting or coorbiting dust is a primary signatur e by which Earth-based observers study the activity and atmosphere of the unusual outer solar system object 2060 Chiron. Therefore, it is im portant to understand the lifetime, dynamics, and loss rates of dust i n its coma, We report here dynamical simulations of particles in Chiro n's collisionless coma. The orbits of 17 920 dust particles were numer ically integrated under the gravitational influence of Chiron, the Sun , and solar radiation pressure. These simulations show that particles ejected from Chiron are more likely to follow suborbital trajectories, or to escape altogether, than to enter quasistable orbits. Significan t orbital lifetimes can only be achieved for very specific launch cond itions. These results call, into question models of a long-term, bound coma generated by discrete outbursts, and instead suggest that Chiron 's coma state is closely coupled to the nearly instantaneous level of Chiron's surface activity.