A dynamical solution of the triple asteroid system (45) Eugenia |
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| Authors: | 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 |
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| Affiliation: | aSETI Institute, 515 N. Whisman Road, Mountain View, CA 94043, USA;bUniversity of California at Berkeley, Department of Astronomy, 601 Campbell Hall, Berkeley, CA 94720, USA;cInstitut de Mécanique Céleste et de Calcul des Éphémérides, Observatoire de Paris, UMR8028 CNRS, 77 av. Denfert-Rochereau, 75014 Paris, France;dFlat Wavefronts, PO BOX 1060, Christchurch 8140, New Zealand;eW.M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743, USA;fSpace Science Institute, 4750 Walnut Street, Boulder, CO 80301-2532, USA |
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| Abstract: | 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 × 10−3 and e ∼ 7 × 10−2 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 J2 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. |
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| Keywords: | Asteroids Asteroids, Dynamics Satellites, Dynamics Infrared observations |
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