Hsieh Henry H, Jewitt David
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA.
Science. 2006 Apr 28;312(5773):561-3. doi: 10.1126/science.1125150. Epub 2006 Mar 23.
Comets are icy bodies that sublimate and become active when close to the Sun. They are believed to originate in two cold reservoirs beyond the orbit of Neptune: the Kuiper Belt (equilibrium temperatures of approximately 40 kelvin) and the Oort Cloud (approximately 10 kelvin). We present optical data showing the existence of a population of comets originating in a third reservoir: the main asteroid belt. The main-belt comets are unlike the Kuiper Belt and Oort Cloud comets in that they likely formed where they currently reside and may be collisionally activated. The existence of the main-belt comets lends new support to the idea that main-belt objects could be a major source of terrestrial water.
彗星是冰质天体，靠近太阳时会升华并变得活跃。人们认为它们起源于海王星轨道之外的两个寒冷区域：柯伊伯带（平衡温度约为40开尔文）和奥尔特云（约10开尔文）。我们展示的光学数据表明，存在一群起源于第三个区域——主小行星带的彗星。主带彗星与柯伊伯带和奥尔特云彗星不同，它们可能在当前所在位置形成，并且可能因碰撞而被激活。主带彗星的存在为“主带天体可能是地球水的主要来源”这一观点提供了新的支持。
