A dynamical solution of the triple asteroid system (45) Eugenia

✍ Scribed by F. Marchis; V. Lainey; P. Descamps; J. Berthier; M. Van Dam; I. de Pater; B. Macomber; M. Baek; D. Le Mignant; H.B. Hammel; M. Showalter; F. Vachier

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 671 KB
• Volume: 210
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1016/j.icarus.2010.08.005

✦ Synopsis

We present the first dynamical solution of the triple asteroid system (45) Eugenia and its two moons Petit-Prince (diameter $ 7 km) and S/2004 (45) 1 (diameter $ 5 km). The two moons orbit at 1165 and 610 km from the primary, describing an almost-circular orbit (e $ 6 Â 10 À3 and e $ 7 Â 10 À2 respectively). The system is quite different from the other known triple systems in the main belt since the inclinations of the moon orbits are sizeable (9°and 18°with respect to the equator of the primary respectively). No resonances, neither secular nor due to Lidov-Kozai mechanism, were detected in our dynamical solution, suggesting that these inclinations are not due to excitation modes between the primary and the moons. A 10-year evolution study shows that the orbits are slightly affected by perturbations from the Sun, and to a lesser extent by mutual interactions between the moons. The estimated J 2 of the primary is three times lower than the theoretical one, calculated assuming the shape of the primary and an homogeneous interior, possibly suggesting the importance of other gravitational harmonics.