论文标题
火山口引起的Yorp效应
The crater-induced YORP effect
论文作者
论文摘要
Yarkovsky-O'Keefe-Radzievskii-Paddack（Yorp）效应在小行星的旋转特性和演变中起着重要作用。虽然对小行星的宏观形状和表面巨石的存在引起的YORP效应已经进行了充分的研究，但尚未对具有给定特性的陨石坑如何影响这种效果进行研究。 我们介绍并估算源自火山口结构的火山口诱导的YORP效应（Cyorp），以研究所得扭矩的幅度，这是通过半分析方法的变化特性和小行星的变化特性的函数。 当火山口的大小约为小行星大小的十分之一，或者当火山口/粗糙度覆盖小行星表面的十分之一时，Cyorp扭矩可以与正常的YORP扭矩相媲美。尽管扭矩随火山口尺寸降低，但是当考虑了常用的幂律陨石坑尺寸分布时，所有小火山口的综合贡献都可能变得不可忽略。通常认为是表面粗糙度的小凹形结构的催化扭矩对于完全计算完整的YORP扭矩至关重要。在碰撞产生的氰基效应下，小行星经过旋转速度和倾斜的随机步行，YORP重置时间尺度通常为0.4 Myr。这对小行星的旋转进化和轨道演变具有很大的影响。 小行星表面上的陨石坑和粗糙度会影响Yorp扭矩，因此会影响小行星的旋转特性和演变。我们建议在未来对YORP对小行星效应的研究中应考虑Cyorp效应。
The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect plays an important role in the rotational properties and evolution of asteroids. While the YORP effect induced by the macroscopic shape of the asteroid and by the presence of surface boulders has been well studied, no investigation has been performed yet regarding how craters with given properties influence this effect. We introduce and estimate the crater-induced YORP effect (CYORP), which arises from the concave structure of the crater, to investigate the magnitude of the resulting torques as a function of varying properties of the crater and the asteroid by a semi-analytical method. The CYORP torque can be comparable to the normal YORP torque when the size of the crater is about one-tenth of the size of the asteroid, or equivalently when the crater/roughness covers one-tenth of the asteroid's surface. Although the torque decreases with the crater size, the combined contribution of all small craters can become non-negligible due to their large number when the commonly used power-law crater size distribution is considered. The CYORP torque of small concave structures, usually considered as surface roughness, is essential to the accurate calculation of the complete YORP torque. Under the CYORP effect that is produced by collisions, asteroids go through a random walk in spin rate and obliquity, with a YORP reset timescale typically of 0.4 Myr. This has strong implications for the rotational evolution and orbital evolution of asteroids. Craters and roughness on asteroid surfaces can influence the YORP torques and therefore the rotational properties and evolution of asteroids. We suggest that the CYORP effect should be considered in the future investigation of the YORP effect on asteroids.
