Ipatov S I, Mather J C
NASA/GSFC, Mail Code 685, Greenbelt, MD 20771, USA.
Ann N Y Acad Sci. 2004 May;1017:46-65. doi: 10.1196/annals.1311.004.
The orbital evolution of about 26,000 Jupiter-crossing objects and 1,500 resonant asteroids under the gravitational influence of planets was investigated. The rate of their collisions with terrestrial planets was estimated by computing the probabilities of collisions based on random-phase approximations and the orbital elements sampled with a 500 yr step. The Bulirsh-Stoer and a symplectic orbit integrator gave similar results for orbital evolution, but sometimes give different collision probabilities with the Sun. For orbits close to that of Comet 2P, the mean collision probabilities of Jupiter-crossing objects with terrestrial planets were greater by two orders of magnitude than for some other comets. For initial orbital elements close to those of Comets 2P, 10P, 44P, and 113P, a few objects (about 0.1%) entered Earth-crossing orbits with semi-major axes a < 2 AU and aphelion distances Q < 4.2 AU, and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myr). Some of them even got inner-Earth orbits (Q < 0.983 AU) and Aten orbits. A few comets achieve typical asteroidal orbits for hundreds of Myr. Most former trans-Neptunian objects that have typical near-Earth object orbits moved in such orbits for millions of years; thus, during most of this time they were extinct comet, if they did not disintegrate.
研究了约26000个近木天体和1500个共振小行星在行星引力影响下的轨道演化。通过基于随机相位近似计算碰撞概率，并以500年步长对轨道要素进行采样，估算了它们与类地行星碰撞的速率。布利尔什 - 斯托尔方法和一种辛轨道积分器给出的轨道演化结果相似，但有时与太阳的碰撞概率不同。对于接近2P彗星轨道的情况，近木天体与类地行星的平均碰撞概率比其他一些彗星大两个数量级。对于初始轨道要素接近2P、10P、44P和113P彗星的情况，少数天体（约0.1%）进入半长轴a < 2天文单位且远日点距离Q < 4.2天文单位的近地轨道，并在这样的轨道上运行超过100万年（长达数十甚至数百万年）。其中一些甚至进入了内地球轨道（Q < 0.983天文单位）和阿登轨道。少数彗星在数百万年里呈现出典型的小行星轨道。大多数具有典型近地天体轨道的原海王星外天体在这样的轨道上运行了数百万年；因此，如果它们没有解体，在这段时间的大部分时间里它们都是灭绝彗星。
