三小行星系统216 Kleopatra 引力场中的动力学

摘要

The triple asteroid system 21 6 Kleopatra in the main-belt is consisted of the primary 21 6 Kleopatra and two moonlets Alexhelios [S/2008(21 6)1]as well as Cleoselene [S/2008 (21 6)2].The primary is a contact binary asteroid which has highly irregular shape and looks like a dumb bell,its three-axes lengths are 21 7 km × 94 km×81 km.Alexhelios is the outer moonlet,with the size of 8.9 km,while Cleoselene is the inner moonlet, with the size of 6.9 km.The dynamical behavior of the triple asteroid system 21 6 Kleopatra contain extremely abundant scientific connotation.This paper studies its dynamic mechanism and the motion law of a spacecraft in the potential field.The dynamical equation expressed in the body-fixed frame of the primary has been analyzed,and the dynamical equations as well as the Jacobi integral of the full three-body problem of the triple asteroid system have been presented.The irregular shape,the orbit and the attitude of these three minor bodies are all considered.A new kind of period-doubling bifurcation in the potential field of the primary of the triple asteroid system 21 6 Kleopatra has been found.The dynamical configuration of this triple asteroid system has been investigated,with considering the irregular gravitational force,the geometrical shape,and the interaction mechanism between these two moonlets. It is found that the irregular shape and the interaction mechanism between these two moonlets cause the orbital parameters of the two moonlets Alexhelios and Cleoselene vary obviously.%主带三小行星系统216 Kleopatra 是由主星216 Kleopatra 及两个小月亮(moonlet)Alexhelios [S/2008(216)1]和 Cleoselene [S/2008(216)2]组成。其中主星216 Kleopatra 是一个具有强不规则形状如哑铃的连接双星,大小为217 km×94 km×81 km,外小月亮 Alexhelios 大小约为8.9 km,内小月亮大小约为6.9 km。其动力学行为具有非常丰富的科学内涵。研究了三小行星系统216 Kleopatra 自身的动力学机制及其引力场中探测器的运动规律,分析了主星质心固连系中探测器的动力学方程,给出了三小行星引力全多体问题的动力学方程及Jacobi 积分,方程考虑了三个小行星的不规则外形、轨道与姿态。发现三小行星系统216 Kleopatra 主星引力场中一种新的周期轨道族的倍周期分岔。考虑主星的不规则精确外形与引力、两个小月亮的相互作用,研究了该三小行星系统的动力学构形。发现 Kleopatra 的强不规则几何外形及两个小月亮 Alexhelios 和 Cleoselene 的相互作用引起两个小月亮的轨道参数的显著变化。