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Moonlets in planetaren Ringen: Implikationen für die Ringteilchendynamik?

行星环中的小卫星：对环粒子动力学的影响？

基本信息

批准号：
164011225
负责人：
Professor Dr. Frank Spahn, Ph.D.
金额：
--
依托单位：
Institut für Physik und Astronomie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/164011225?language=en
关键词：
Moonlets planetaren Ringen Implikationen die

项目摘要

The prediction of propeller structures in Satum s rings caused by embedded small satellites (moonlets) by Spahn and Sremcevic (2000), Sremcevic et al. (2002) and Seiß et al. (2005) led to recent detections of moonlets in Saturn s rings (Tiscareno et al., 2006; Sremcevic et al., 2007; Tiscareno et al., 2008). The brightness of the propeller structures, however, deviated from the formerly predicted features. A preliminary photometric study of particle configurations obtained from N-body simulations demonstrated that the brightness of the propeller pattern can in principle be understood if small debris particles are produced in perturbed regions (Sremcevic et al., 2007). This debris, formerly resting on the surfaces of larger ring particles, can be released due to enhanced impact velocities in perturbed ring regions, in this way increasing the brightness of the observed propeller features. The aim of the project is to calculate the change of the particles size distribution of an ensemble of adhering and gravitating ring particles due to perturbations. The resulting modifications of the optical depth will then be determined and related to the observed propellers. In this way an improved understanding of the dependence of the observed pattern in the ring brightness on the underlying perturbation in the mass density can be obtained. This will in turn lead to improved constraints for the mass of the embedded moonlets, the ring viscosity as well as an estimate for the strength of the adhesion between the ring particles and its importance for the ring particle size distribution. A model for the change of the size distribution in perturbed ring regions could also be applied to other ring features as the missing ring brightness asymmetry effect in the outermost A ring, the brightness halos around strong resonances (e.g. Janus 5:4 density wave, Nicholson et al. (2008)) and the temporary clumps and brightness bursts in Saturn s F ring.

Spahn和Sremcevic（2000年）、Sremcevic等人（2002年）和Seibalan等人（2005年）对土星环中由嵌入式小卫星（小卫星）引起的螺旋桨结构的预测导致了最近对土星环中小卫星的探测（Tiscareno等人，2006; Sremcevic等人，2007; Tiscareno等人，2008年）。然而，螺旋桨结构的亮度偏离了先前预测的特征。对N体模拟获得的粒子配置的初步光度研究表明，如果在扰动区域产生小碎片粒子，原则上可以理解螺旋桨图案的亮度（Sremcevic等人，2007年）。这些碎片以前停留在较大的环颗粒表面，由于扰动环区域的撞击速度增加，可以释放出来，从而增加了所观察到的螺旋桨特征的亮度。该项目的目的是计算由于扰动而引起的粘附和引力环粒子系综的粒子尺寸分布的变化。然后将确定光学深度的所得修改，并将其与所观察到的螺旋桨相关联。通过这种方式，可以更好地理解所观察到的环亮度图案对质量密度中的潜在扰动的依赖性。这将反过来导致改进的约束嵌入的小卫星的质量，环粘度，以及估计环颗粒之间的粘附力的强度和它的重要性的环粒度分布。扰动环区域的大小分布变化模型也可以应用于其他环的特征，如最外层A环中缺失的环亮度不对称效应，强共振周围的亮度晕（例如Janus 5：4密度波，Nicholson et al.（2008））以及土星F环中的临时团块和亮度爆发。