Discovery of a moon orbiting the asteroid 45 Eugenia

W. J. Merline, L. M. Close, C. Dumas, C. R. Chapman, F. Roddier, F. Ménard, D. C. Slater, G. Duvert, C. Shelton, T. Morgan

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96 Scopus citations


Evidence for asteroidal satellites (moons) had been sought for decades, because the relative frequency of such satellites will bear on the collisional history of the asteroid belt and the Solar System, yet only one has been detected unambiguously. Here we report the discovery of a satellite of the asteroid 45 Eugenia, using an adaptive optics system on a ground-based telescope. The satellite has a diameter of about 13 km, and an orbital period of about 4.7 days with a separation of 1,190 km from Eugenia. Using a previously determined diameter for Eugenia, we estimate that its bulk density is about 1.2 g cm, which is similar to that of the C-type asteroid Mathilde. This implies that Eugenia, also a low-albedo C-type asteroid, may be a rubble pile, or composed of primitive, icy materials of low bulk density.

Original languageEnglish (US)
Pages (from-to)565-568
Number of pages4
Issue number6753
StatePublished - Oct 7 1999

ASJC Scopus subject areas

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