The orbital migration of Jovian planets is believed to have played an important role in shaping the Kuiper Belt. We investigate the effects of the long time-scale （2 ×107 yr） migration of Jovian planets on the ...The orbital migration of Jovian planets is believed to have played an important role in shaping the Kuiper Belt. We investigate the effects of the long time-scale （2 ×107 yr） migration of Jovian planets on the orbital evolution of massless test particles that are initially located beyond 28 AU. Because of the slowness of the migration, Neptune＇s mean motion resonances capture test particles very efficiently. Taking into account the stochastic behavior during the planetary migration and for proper parameter values, the resulting concentration of objects in the 3：2 resonance is prominent, while very few objects enter the 2：1 resonance, thus matching the observed Kuiper Belt objects very well. We also find that such a long time-scale migration is favorable for exciting the inclinations of the test particles, because it makes the secular resonance possible to operate during the migration. Our analyses show that the us secular resonance excites the eccentricities of some test particles, so decreasing their perihelion distances, leading to close encounters with Neptune, which can then pump the inclinations up to 20°.展开更多
太阳星云气体的耗散可以引起长期共振迁移（secular resonance sweeping，SRS），当长期共振的位置扫过经典Kuiper带小天体（Kuiper Belt objects，KBOs），就会激发其轨道倾角．详细研究了在太阳系紧致构形中（指四个大行星轨道彼此相...太阳星云气体的耗散可以引起长期共振迁移（secular resonance sweeping，SRS），当长期共振的位置扫过经典Kuiper带小天体（Kuiper Belt objects，KBOs），就会激发其轨道倾角．详细研究了在太阳系紧致构形中（指四个大行星轨道彼此相距较小的状态）SRS对经典KBOs轨道倾角的激发过程，发现KBOs轨道倾角受激发的程度敏感地依赖于星云气体中面与太阳系不变平面^1 的夹角δ：当星云气体中面与不变平面重合，即δ=0时，经典KBOs倾角受到的激发很小；而当星云气体中面与黄道面重合，即δ≈1．6^。时，在合理的初始条件下，经典KBOs的倾角最高可以被激发到30^。以上,另外，通过模拟木星具有较大轨道倾角的情形以及SRS和大行星轨道迁移同时发生的情形，发现对于经典KBOs倾角的受激发程度而言，它们两者的影响都远弱于6．展开更多
The population of Neptune Trojans is believed to be bigger than that of Jupiter Trojans and that of asteroids in the main belt, although only eight members of this distant asteroid swarm have been observed up to now. ...The population of Neptune Trojans is believed to be bigger than that of Jupiter Trojans and that of asteroids in the main belt, although only eight members of this distant asteroid swarm have been observed up to now. Six leading Neptune Trojans around the Lagrange point L4 discovered earlier have been studied in detail, but two trailing ones found recently around the L5 point, 2004 KV18 and 2008 LC18, have not yet been investigated. We report our investigations on the dynamical behaviors of these two new Neptune Trojans. Our calculations show that the asteroid 2004 KV18 is a temporary Neptune Trojan. Most probably, it was captured into the trailing Trojan cloud no earlier than 2.03 ×105 yr ago, and it will not maintain this position later than 1.65 × 105 yr in the future. Based on the statistics from our orbital simulations, we ar- gue that this object is more like a scattered Kuiper belt object. By contrast, the orbit of 2008 LC18 is much more stable. Among the clone orbits spreading within the orbital uncertainties, a considerable portion of clones may survive on the L5 tadpole orbits for 4 Gyr. The strong dependence of the stability on the semimajor axis and resonant angle suggests that further observations are badly required to constrain the orbit in the stable region. We also discuss the implications of the existence and dynamics of these two trailing Trojans over the history of the solar system.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘The orbital migration of Jovian planets is believed to have played an important role in shaping the Kuiper Belt. We investigate the effects of the long time-scale （2 ×107 yr） migration of Jovian planets on the orbital evolution of massless test particles that are initially located beyond 28 AU. Because of the slowness of the migration, Neptune＇s mean motion resonances capture test particles very efficiently. Taking into account the stochastic behavior during the planetary migration and for proper parameter values, the resulting concentration of objects in the 3：2 resonance is prominent, while very few objects enter the 2：1 resonance, thus matching the observed Kuiper Belt objects very well. We also find that such a long time-scale migration is favorable for exciting the inclinations of the test particles, because it makes the secular resonance possible to operate during the migration. Our analyses show that the us secular resonance excites the eccentricities of some test particles, so decreasing their perihelion distances, leading to close encounters with Neptune, which can then pump the inclinations up to 20°.
基金Supported by the National Natural Science Foundation of Chinasupported by the Natural Science Foundation of China (NSFC+2 种基金Grant Nos. 10833001 and 11073012)the Qing Lan Project (Jiangsu Province)J. Li is also supported by the NSFC (Grant Nos. 1103008 and 11078001)
文摘The population of Neptune Trojans is believed to be bigger than that of Jupiter Trojans and that of asteroids in the main belt, although only eight members of this distant asteroid swarm have been observed up to now. Six leading Neptune Trojans around the Lagrange point L4 discovered earlier have been studied in detail, but two trailing ones found recently around the L5 point, 2004 KV18 and 2008 LC18, have not yet been investigated. We report our investigations on the dynamical behaviors of these two new Neptune Trojans. Our calculations show that the asteroid 2004 KV18 is a temporary Neptune Trojan. Most probably, it was captured into the trailing Trojan cloud no earlier than 2.03 ×105 yr ago, and it will not maintain this position later than 1.65 × 105 yr in the future. Based on the statistics from our orbital simulations, we ar- gue that this object is more like a scattered Kuiper belt object. By contrast, the orbit of 2008 LC18 is much more stable. Among the clone orbits spreading within the orbital uncertainties, a considerable portion of clones may survive on the L5 tadpole orbits for 4 Gyr. The strong dependence of the stability on the semimajor axis and resonant angle suggests that further observations are badly required to constrain the orbit in the stable region. We also discuss the implications of the existence and dynamics of these two trailing Trojans over the history of the solar system.
