Astron. Astrophys. 354, 1091-1100 (2000)

Thersites: a `jumping' Trojan?

K. Tsiganis ^1,2, R. Dvorak ² and E. Pilat-Lohinger <sup>2

1</sup> Section of Astrophysics Astronomy & Mechanics, Department of Physics, University of Thessaloniki, 540 06 Thessaloniki, Greece (tsiganis@astro.auth.gr)
² Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, 1180 Vienna, Austria (dvorak,lohinger@astro.univie.ac.at)

Received 11 June 1999 / Accepted 8 November 1999

Abstract

In this paper, we examine the dynamical evolution of the asteroid (1868) Thersites ¹, a member of the Trojan belt. Thersites is librating around the Lagrangian point , 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 Solar System model (OSS), which consists of the Sun and the four giant planets. Our results indicate that the probability that this asteroid will eventually escape from the Trojan swarm is rather high. In fact, from our initial 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 planets are found to be responsible for this chaotic behavior. The width of libration and eccentricity values that lead to grossly unstable orbits are calculated and compared with previously known results on the stability of the Trojans. Finally, a very interesting behavior has been observed for one of the escaping asteroids as he `jumped' from to where he remained performing a highly inclined libration for Myrs before escaping from the Trojan swarm.

Key words: minor planets, asteroids celestial mechanics, stellar dynamics chaos

Send offprint requests to: K. Tsiganis

© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000

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