The Evolution of Long-Period Comets
The Evolution of Long-Period Comets
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DOI：
10.1006/icar.1998.6040
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发表时间：
1997-05
期刊：
影响因子：
3.2
通讯作者：
P. Wiegert;S. Tremaine
中科院分区：
文献类型：
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作者：
P. Wiegert;S. Tremaine
我们研究的演化长周期彗星的轨道，一个更现实的动力学方法比以前用于研究这个问题的蒙特卡罗和分析方法的数值积分。我们在由太阳、四颗巨行星和银河潮汐组成的模型太阳系中跟踪彗星，从它们在奥尔特云中的起源，直到它们最终逃逸或毁灭。我们还研究了非引力的影响，以及从一个假设的太阳伴星或环日盘的引力。我们证实了奥尔特和其他研究人员的结论，即观测到的长周期彗星轨道分布与预期的稳态分布不匹配，除非有衰落或一些类似的物理过程耗尽了老年彗星的人口。我们研究几个简单的衰落规律。我们可以匹配观测到的轨道分布，如果彗星剩余的可观测的后映射的比例是10 m−0.6±0.1（接近最初由维普莱1962年提出的衰落定律）;或者如果大约95%的彗星只存在几次（106次）返回，其余的无限期地持续下去。我们的研究结果还产生统计数据，如预期的近日点分布，远日点方向的分布，与巨行星相遇的频率和哈雷型彗星的生产率。
We study the evolution of long-period comets by numerical integration of their orbits, a more realistic dynamical approach than the Monte Carlo and analytic methods previously used to study this problem. We follow the comets from their origin in the Oort cloud until their final escape or destruction, in a model solar system consisting of the Sun, the four giant planets and the Galactic tide. We also examine the effects of nongravitational forces as well as the gravitational forces from a hypothetical solar companion or circumsolar disk. We confirm the conclusion of Oort and other investigators that the observed distribution of long-period comet orbits does not match the expected steady-state distribution unless there is fading or some similar physical process that depletes the population of older comets. We investigate several simple fading laws. We can match the observed orbit distribution if the fraction of comets remaining observable aftermapparitions is ∝m−0.6±0.1(close to the fading law originally proposed by Whipple 1962); or if approximately 95% of comets live for only a few (∼6) returns and the remainder last indefinitely. Our results also yield statistics such as the expected perihelion distribution, distribution of aphelion directions, frequency of encounters with the giant planets and the rate of production of Halley-type comets.