Observatório Nacional/MCTI, Rua General José Cristino 77, CEP 20921-400 Rio de Janeiro, RJ, Brazil.
LESIA, Observatoire de Paris, CNRS UMR 8109, Université Pierre et Marie Curie, Université Paris-Diderot, 5 place Jules Janssen, F-92195 Meudon Cedex, France.
Nature. 2014 Apr 3;508(7494):72-5. doi: 10.1038/nature13155. Epub 2014 Mar 26.
Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ± 9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites.
迄今为止，人们仅在太阳系的四颗巨行星周围发现了环。环是天然实验室，可以研究类似于行星系统和星系形成过程的动力学过程。它们的存在也告诉我们它们所环绕的天体的起源和演化。在这里，我们报告了对多根恒星掩星的观测结果，该观测结果显示，在半人马座（10199）Chariklo 周围存在一个环系，它是一个半人马座——也就是说，它是一类主要在木星和海王星之间运行的小型天体之一——等效半径为 124±9 公里（参考文献 2）。有两个密度较大的环，分别宽约 7 公里和 3 公里，光学厚度分别为 0.4 和 0.06，轨道半径分别为 391 公里和 405 公里。目前环的取向与 2008 年的边缘几何形状一致，这为 Chariklo 系统在 1997 年至 2008 年间的变暗以及在同一时期其光谱中冰和其他吸收特征的逐渐消失提供了简单的解释。这意味着这些环部分由水冰组成。它们可能是碎片盘的残余物，可能被嵌入的、公里级别的卫星所限制。
