A low density of 0.8 g cm-3 for the Trojan binary asteroid 617 Patroclus

  title={A low density of 0.8 g cm-3 for the Trojan binary asteroid 617 Patroclus},
  author={Franck Marchis and Daniel Hestroffer and Pascal Descamps and J{\'e}r{\^o}me Berthier and Antonin H. Bouchez and Randall D. Campbell and Jason C. Y. Chin and Marcos A. van Dam and Scott K. Hartman and Erik M. Johansson and Robert Lafon and David Le Mignant and Imke de Pater and Paul J. Stomski and Douglas M. Summers and Fr{\'e}d{\'e}ric Vachier and Peter L. Wizinovich and Michael H. Wong},
The Trojan population consists of two swarms of asteroids following the same orbit as Jupiter and located at the L4 and L5 stable Lagrange points of the Jupiter–Sun system (leading and following Jupiter by 60°). The asteroid 617 Patroclus is the only known binary Trojan. The orbit of this double system was hitherto unknown. Here we report that the components, separated by 680 km, move around the system's centre of mass, describing a roughly circular orbit. Using this orbital information… 
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