Libration and migration of propeller moons in Saturns dense rings

土星致密环中螺旋桨卫星的平移和迁移

• 批准号: 252107923
• 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: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/252107923?language=en
• 关键词: Libration; migration; propeller; moons; Saturns

One of the most interesting findings of the Cassini-mission has been a Non-Keplerian excess motion of the largest propeller moonlets. Studies in the first project phase have indicated that these longitudinal librations might be excited by near-resonant perturbations caused by the numerous Saturnian satellites, while ring-moonlet interactions have the potential to amplify the libration amplitude, as suggested by our linearized moonlet-propeller model. In the continuation phase we plan to complete our numerical modeling of the resonantly driven moonlet-libration by incorporating dissipative effects mimicking the numerous irreversible moonlet-ring interactions (physical collisions, gravitational scattering). With this approach stationary libration properties can be expected and their dependence on the dissipation rate could help to identify dominating librations. The amplification of these certain libration amplitudes - demonstrated by the linearized moonlet-propeller oscillator for a single mode in the previous project phase - will now be modeled by hydrodynamic simulations of a moonlet freely moving in a dense granular ring-fluid. This approach will permit us to capture the non-linear character of the moonlet-propeller interactions, which may allow the excitement and amplification of multiple (interacting) libration modes. Further, we will compare the related results with the current Cassini imaging data.

卡西尼号任务最有趣的发现之一是最大的螺旋桨卫星的非开普勒过度运动。项目第一阶段的研究表明，这些纵向振动可能是由众多土星卫星引起的近共振扰动激发的，而环-小卫星的相互作用有可能放大振动幅度，正如我们的线性小卫星-螺旋桨模型所表明的那样。在继续阶段，我们计划通过结合模拟众多不可逆小卫星环相互作用（物理碰撞、引力散射）的耗散效应来完成共振驱动小卫星平动的数值模拟。通过这种方法，可以预期静态振动特性，并且它们对耗散率的依赖性可以帮助识别主要振动。这些某些振动幅度的放大（由先前项目阶段的单模线性小卫星螺旋桨振荡器证明）现在将通过在致密颗粒环流体中自由移动的小卫星的流体动力学模拟来建模。这种方法将使我们能够捕获小卫星-螺旋桨相互作用的非线性特征，这可能允许多种（相互作用的）振动模式的激发和放大。进一步，我们将相关结果与当前卡西尼号成像数据进行比较。

项目成果

Hydrodynamic Simulations of Moonlet-induced Propellers in Saturn’s Rings: Application to Blériot

土星环中小卫星引起的螺旋桨的流体动力学模拟：在 Blériot 中的应用

• DOI: 10.3847/1538-3881/aaed44
• 发表时间: 2017
• 期刊: The Astronomical Journal
• 作者: M. Seiß;N. Albers;M. Sremčević;J. Schmidt;H. Salo;M. Seiler;H. Hoffmann;F. Spahn
• 通讯作者: F. Spahn

Hydrodynamic Simulations of Asymmetric Propeller Structures in Saturn's Rings

土星环中不对称螺旋桨结构的流体动力学模拟

• DOI: 10.3847/1538-4365/ab26b0
• 发表时间: 2019
• 期刊: The Astrophysical Journal Supplement Series
• 作者: M. Seiler;M. Seiß;H. Hoffmann;F. Spahn
• 通讯作者: F. Spahn