冥族小天体与海王星特洛伊的近密交会  

The Frequency of Close Encounters and Collisions Between Plutinos and Neptune Trojans

作　　者：董城昱 周礼勇[1,2] DONG Cheng-yu;ZHOU Li-yong(School of Astronomy and Space Science, Nanjing University, Nanjing 210046, China;Key Laboratory of Modern Astrophysics in Ministry of Education, Nanjing University, Nanjing 210046, China)

机构地区：[1]南京大学天文与空间科学学院,南京210046 [2]南京大学现代天文与天体物理教育部重点实验室,南京210046

出　　处：《天文学进展》2019年第3期322-336,共15页Progress In Astronomy

基　　金：国家自然科学基金(11473016,11333002)

摘　　要：海王星外天体中的冥族小天体与海王星成2:3的平运动轨道共振,且具有较大的轨道偏心率,因此它们能与海王星特洛伊的轨道发生重叠,导致近密交会和碰撞,从而深刻地影响两者的动力学演化。利用数值模拟的方法,有效地获得了这两群小天体间近密交会的信息,讨论了可能影响两者近密交会频率的因素,包括小天体质量、轨道倾角和轨道偏心率等。在合理近似条件下,建立了估算两群小天体近密交会和碰撞次数的理论公式。结合已有的数值模拟结果,以及对冥族小天体观测数据的分析,对实际情况下冥族小天体群与典型特洛伊小天体之间的近密交会和碰撞次数进行了估算,证明近密交会较为频繁地发生,而碰撞则极其罕见,并且各尺寸范围的小天体对近密交会和碰撞次数的贡献各有不同。这一套分析和估算的方法可以直接应用在其他类似小天体间交会过程的估算上。As a subpopulation of trans-Neptunian objects(TNO), Plutinos(PL) are located in the 2:3 mean motion resonance with Neptune, and possess high eccentricity, which allows their orbits overlap Neptune Trojans’(TR) significantly, yielding potential close encounters and collisions that influence the dynamical evolutions of these two groups of asteroids. Based on the improved numerical tools that properly handle the close encounters in the simulations,we investigate the key factors that affect the frequency of close encounters, including mass,inclination and eccentricity. Under reasonable assumptions, we build analytical formula to estimate the number of close encounters and collisions between these two groups. Together with numerical results and existing observation data of PLs, we estimate the number of close encounters and collisions that PLs bring to a typical TR in realistic cases. We find that the close encounters are frequent, but collisions are extremely rare, and planetesimals with different mass contribute differently. Our analytical tool can be applied to the evaluation of encounters between other groups of asteroids as well.

关 键 词：海王星特洛伊天体 近密交会 分析与数值方法 

分 类 号：P134[天文地球—天体力学]