Stern S A, Weaver H A, Steffl A J, Mutchler M J, Merline W J, Buie M W, Young E F, Young L A, Spencer J R
Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, Colorado 80302, USA.
Nature. 2006 Feb 23;439(7079):946-8. doi: 10.1038/nature04548.
The two newly discovered satellites of Pluto (P1 and P2) have masses that are small compared to both Pluto and Charon-that is, between 5 x 10(-4) and 1 x 10(-5) of Pluto's mass, and between 5 x 10(-3) and 1 x 10(-4) of Charon's mass. This discovery, combined with the constraints on the absence of more distant satellites of Pluto, reveal that Pluto and its moons comprise an unusual, highly compact, quadruple system. These facts naturally raise the question of how this puzzling satellite system came to be. Here we show that P1 and P2's proximity to Pluto and Charon, the fact that P1 and P2 are on near-circular orbits in the same plane as Pluto's large satellite Charon, along with their apparent locations in or near high-order mean-motion resonances, all probably result from their being constructed from collisional ejecta that originated from the Pluto-Charon formation event. We also argue that dust-ice rings of variable optical depths form sporadically in the Pluto system, and that rich satellite systems may be found--perhaps frequently--around other large Kuiper belt objects.
新发现的冥王星的两颗卫星（P1和P2）的质量，与冥王星和卡戎相比都很小——也就是说，它们的质量在冥王星质量的5×10⁻⁴到1×10⁻⁵之间，在卡戎质量的5×10⁻³到1×10⁻⁴之间。这一发现，再加上对冥王星不存在更远卫星的限制，表明冥王星及其卫星构成了一个不同寻常的、高度紧凑的四重系统。这些事实自然而然地引出了一个问题：这个令人困惑的卫星系统是如何形成的。我们在此表明，P1和P2与冥王星和卡戎的接近程度，P1和P2在与冥王星的大卫星卡戎同一平面内的近圆形轨道上这一事实，以及它们明显处于高阶平均运动共振或其附近的位置，所有这些可能都源于它们是由源自冥王星 - 卡戎形成事件的碰撞抛射物构成的。我们还认为，冥王星系统中会偶尔形成光学深度可变的尘埃 - 冰环，并且在其他大型柯伊伯带天体周围可能——也许经常——会发现丰富的卫星系统。
