Marchis Franck, Hestroffer Daniel, Descamps Pascal, Berthier Jérôme, Bouchez Antonin H, Campbell Randall D, Chin Jason C Y, van Dam Marcos A, Hartman Scott K, Johansson Erik M, Lafon Robert E, Le Mignant David, de Pater Imke, Stomski Paul J, Summers Doug M, Vachier Frédéric, Wizinovich Peter L, Wong Michael H
Department of Astronomy, University of California, 601 Campbell Hall, Berkeley, California 94720, USA.
Nature. 2006 Feb 2;439(7076):565-7. doi: 10.1038/nature04350.
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 degrees ). 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, combined with thermal measurements to estimate the size of the components, we derive a very low density of 0.8(- 0.1)+0.2 g cm(-3). The components of 617 Patroclus are therefore very porous or composed mostly of water ice, suggesting that they could have been formed in the outer part of the Solar System.
特洛伊小行星群由两群小行星组成，它们与木星沿着相同轨道运行，位于木星 - 太阳系统的L4和L5稳定拉格朗日点（分别在木星前方和后方60度处）。小行星617帕特罗克洛斯是已知的唯一一颗双小行星特洛伊天体。此前，这个双星系统的轨道一直不为人知。在此，我们报告称，该双星系统的两个组成部分相距680千米，围绕系统质心运行，描绘出一个大致为圆形的轨道。利用这一轨道信息，并结合热测量来估算组成部分的大小，我们得出其密度非常低，为0.8（-0.1）+0.2克/立方厘米。因此，617帕特罗克洛斯的组成部分孔隙率非常高，或者主要由水冰构成，这表明它们可能形成于太阳系的外部。
