标题： 木星族彗星和共振小行星向近地空间的迁移 显示英文标题

标题： Migration of Jupiter-Family Comets and Resonant Asteroids to Near-Earth Space

摘要： 研究了约20000个木星穿越天体和1500个共振小行星在行星引力作用下的轨道演化。 通过基于随机相位近似计算碰撞概率并以500年步长采样轨道元素，估计了它们与类地行星的碰撞率。 对于接近2P彗星轨道的天体，木星穿越天体与类地行星的平均碰撞概率比其他一些彗星高两个数量级。 对于初始轨道元素接近2P、10P、44P和113P彗星的少数天体（~0.1%），获得了半长轴a<2 AU的地球穿越轨道，并在此类轨道上运动超过1百万年（甚至达到数千万年）。 其中一些天体甚至获得了近日地轨道（即近日点距离Q<0.983 AU）和阿特恩轨道。 大多数具有典型近地天体轨道的过去跨海王星天体如果未解体成小彗星，则在数百万年内保持此类轨道，因此在这段时间的大部分时间内它们是已灭绝的彗星。 显示英文摘要

摘要： The orbital evolution of about 20000 Jupiter-crossing objects and 1500 resonant asteroids under the gravitational influence of planets was investigated. The rate of their collisions with the 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 integrators gave similar results for orbital evolution, but sometimes gave different collision probabilities with the Sun. For orbits close to that of Comet 2P, the mean collision probabilities of Jupiter-crossing objects with the 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 (~0.1%) got Earth-crossing orbits with semi-major axes a<2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Some of them even got inner-Earth orbits (i.e., with aphelion distance Q<0.983 AU) and Aten orbits. Most former trans-Neptunian objects that have typical near-Earth object orbits moved in such orbits for millions of years (if they did not disintegrate into mini-comets), so during most of this time they were extinct comets.