Thersites: a 'jumping' Trojan?

In this paper, we examine the dynamical evolution of the asteroid (1868) Th ersites(1), a member of the Trojan belt. Thersites is librating around the Lagrangian point L-4, following, however, a chaotic orbit. The equations of motion for Thersites as well as for a distribution of neighboring initial conditions are integrated numerically for 50 million years in the Outer Sol ar System model (OSS), which consists of the Sun and the four giant planets . Our results indicate that the probability that this asteroid will eventua lly escape from the Trojan swarm is rather high. In fact, 20% from our init ial distribution escaped within the integration time. Many of the remaining ones also show characteristic 'jumps' in the orbital elements, especially the inclination. Secular resonances involving the nodes of the outer planet s are found to be responsible for this chaotic behavior. The width of libra tion and eccentricity values that lead to grossly unstable orbits are calcu lated and compared with previously known results on the stability of the Tr ojans. Finally, a very interesting behavior has been observed for one of th e escaping asteroids as he 'jumped' from L-4 to L-5 where he remained perfo rming a highly inclined libration for similar to 2 Myrs before escaping fro m the Trojan swarm.