Rotation rate and velocity dispersion of planetary ring particles with size distribution II. Numerical simulation for gravitating particles
Rotation rate and velocity dispersion of planetary ring particles with size distribution II. Numerical simulation for gravitating particles
复制标题
具有尺寸分布的行星环颗粒的转速和速度分散度II。
DOI：
10.1016/j.icarus.2006.03.010
复制
发表时间：
2006
期刊：
影响因子：
3.2
通讯作者：
K. Ohtsuki
中科院分区：
文献类型：
--
作者：
K. Ohtsuki
在Ohtsuki [Ohtsuki，K.，2006.具有尺寸分布的行星环颗粒的转速和速度弥散。I.公式化和解析计算。Icarus 183，373-383]。我们得到的粒子旋转速率和速度色散的演变率，使用三体轨道积分，考虑到随机速度和旋转速率的分布。得到的搅拌和摩擦率被用来计算在一个和两个尺寸的组件环以及那些具有窄的尺寸分布的粒子的速度分散和旋转速率的演变，并与N体模拟的协议被确认。然后，我们进行计算，以检查平衡旋转速率和速度分散的引力环粒子具有广泛的尺寸分布，从1厘米到10米。我们发现小粒子快速自旋，其中ω和Ω分别是粒子的旋转速率和轨道角频率，而最大的粒子自旋缓慢，[公式：见正文]。快速旋转的小颗粒的垂直刻度高度远大于缓慢旋转的大颗粒。因此，环粒子的旋转状态具有垂直不均匀性，这应该考虑到从土星环的热红外辐射建模。
We examine rotation rates of gravitating particles in low optical depth rings, on the basis of the evolution equation of particle rotational energy derived by Ohtsuki [Ohtsuki, K., 2006. Rotation rate and velocity dispersion of planetary ring particles with size distribution. I. Formulation and analytic calculation. Icarus 183, 373–383]. We obtain the rates of evolution of particle rotation rate and velocity dispersion, using three-body orbital integration that takes into account distribution of random velocities and rotation rates. The obtained stirring and friction rates are used to calculate the evolution of velocity dispersion and rotation rate for particles in one- and two-size component rings as well as those with a narrow size distribution, and agreement with N-body simulation is confirmed. Then, we perform calculations to examine equilibrium rotation rates and velocity dispersion of gravitating ring particles with a broad size distribution, from 1 cm up to 10 m. We find that small particles spin rapidly with [Formula: see text] , where ω and Ω are the particle rotation rate and its orbital angular frequency, respectively, while the largest particles spin slowly, with [Formula: see text] . The vertical scale height of rapidly rotating small particles is much larger than that of slowly rotating large particles. Thus, rotational states of ring particles have vertical heterogeneity, which should be taken into account in modeling thermal infrared emission from Saturn's rings.