ANALYTIC THEORY FOR THE YARKOVSKY–O'KEEFE–RADZIEVSKI–PADDACK EFFECT ON OBLIQUITY
ANALYTIC THEORY FOR THE YARKOVSKY–O'KEEFE–RADZIEVSKI–PADDACK EFFECT ON OBLIQUITY
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YARKOVSKY-OKEEFE-RADZIEVSKI-PADDACK 倾角效应的解析理论
DOI：
10.1088/0004-6256/136/1/291
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
D. Vokrouhlický
中科院分区：
文献类型：
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作者：
D. Nesvorný;D. Vokrouhlický
Yarkovsky-O 'Keefe-Radzievski-Paddack（YORP）效应是一种热辐射力矩，它使小物体加速或减慢其旋转并改变其自旋矢量方向。这种效应对直径D = 50 km的小行星的自旋动力学有重要的影响。在我们以前的工作中，我们开发了一个分析理论的组成部分的YORP扭矩，影响自旋速率。在这里，我们扩展这些计算来确定YORP扭矩对结晶度的影响。我们的理论仅限于近似球形的物体。研究了两种极限情况：（1）当表面热导率K = 0时，热能的立即释放;（2）当表面温度随时间变化很小时，K = 0的影响。我们使用线性化的热输运方程来模拟（2）。结果包括显式缩放的YORP扭矩结晶度的物理和动力学参数，如热导率和自旋速率。力矩对刚度的依赖关系以勒让德多项式的级数形式给出。比较表明，分析结果与小行星1998 KY 26和（66391）1999 KW 4等物体的数值计算的YORP扭矩非常吻合。我们认为，一个重要的部分，主带小行星可能有特定的dielity值（广义Slivan状态）所产生的勒让德多项式的根。
The Yarkovsky–O'Keefe–Radzievski–Paddack (YORP) effect is a thermal radiation torque that causes small objects to speed up or slow down their rotation and modify their spin vector orientation. This effect has important implications for spin dynamics of diameter D ≲ 50 km asteroids. In our previous work we developed an analytic theory for the component of the YORP torque that affects the spin rate. Here we extend these calculations to determine the effect of the YORP torque on obliquity. Our theory is limited to objects with near-spherical shapes. Two limiting cases are studied: (1) immediate emission of the thermal energy that occurs for surface thermal conductivity K = 0; (2) the effects of K ≠ 0 in the limit of small temporal variations of the surface temperature. We use the linearized heat transport equation to model (2). The results include explicit scaling of the YORP torque on obliquity with physical and dynamical parameters such as the thermal conductivity and spin rate. The dependence of torques on the obliquity is given as series of the Legendre polynomials. Comparisons show excellent agreement of the analytic results with the numerically calculated YORP torques for objects such as asteroids 1998 KY26 and (66391) 1999 KW4. We suggest that an important fraction of main belt asteroids may have specific obliquity values (generalized Slivan states) arising from the roots of the Legendre polynomials.