RUI: Saturn's Rings

这个项目的目标是通过全面研究土星环的视亮度随光环经度的戏剧性变化，加深对土星环的动力学和结构的了解。这种方位亮度不对称通常归因于引力尾迹--试图在相互引力下聚集的环状粒子，但受到土星强大的潮汐影响而受挫。韦尔斯利学院的理查德·弗伦奇博士将把从数百张哈勃太空望远镜图像和阿雷西博天文台的多个雷达图像中测量到的不对称性，与引力尾迹的动力学模型的预测进行比较。对环的详细结构和由此产生的引力尾迹的N体模拟表明，环的详细属性非常依赖于环的详细属性，如粒子尺寸分布、表面质量密度和粒子间碰撞的弹性。由于目前还不完全了解的原因，所产生的不对称性的强度在环之间也有很大的不同。例如，这项工作将量化新发现的内B环中的方位不对称。这个项目将引起行星科学家的普遍兴趣，因为它结合了两个互补的、极高质量的数据集(十年的HST观测和几年的阿雷西博雷达结果)和对环的真实物理描述。这项研究将解决环动力学的基本特征，如引力不稳定性，以及环粒子本身的性质。这些观测和分析将为卡西尼号对环的任务调查提供坚实的基础。HST和阿雷西博数据不会被卡西尼观测所取代，因为它们是在不同的观测几何下拍摄的，并且它们采样了粒子散射相函数的非常不同的部分。研究人员将把这项研究与卫尔斯理学院的教育生活联系起来。卫尔斯理学院是一所本科女子学院，在女性科学教育方面取得了成功的历史。这将通过指导荣誉论文学生和本科生暑期学生，并在入门和高级课程中纳入他们研究的详细实例来实现。弗兰奇博士将继续一项成功的外展计划，每年为大约25名K-12教师主持为期几天的研讨会，讨论现代行星科学与地球问题(如全球气候变化和巨大撞击的后果)之间的关系，并将在该项目下与教师和普通公众在非技术层面上分享正在进行的研究。该奖项是根据NSF本科生机构研究计划颁发的。*

AST 0307800FrenchThe objective of this project is to develop a deeper understanding of the dynamics and structure of Saturn's rings, through a comprehensive investigation of dramatic variations in their apparent brightness with ring longitude. This azimuthal brightness asymmetry is generally ascribed to gravitational wakes -- clumps of ring particles attempting to accrete under their mutual gravitation, but frustrated in the attempt by Saturn.s strong tidal influence. Dr. Richard French, at Wellesley College, will compare measurements of the asymmetry from a rich set of hundreds of Hubble Space Telescope images and multiple radar images of the rings from Arecibo Observatory, with the predictions of dynamical models of gravitational wakes. The N-body simulations of the detailed structure of the rings, and the resulting gravitational wakes, show a very strong dependence on the detailed properties of the rings, such as the distribution of particle sizes, the surface mass density, and the elasticity of interparticle collisions. The strength of the resulting asymmetry also varies greatly across the rings, for reasons that are not yet completely understood. This work will quantify the newly-discovered azimuthal asymmetry in the inner B ring, for example. This project will be of general interest to planetary scientists because it combines two complementary, superb quality data sets (a decade of HST observations and several years of Arecibo radar results) with a realistic physical description of the rings. The research will address fundamental characteristics of ring dynamics, such as gravitational instabilities, as well as properties of the ring particles themselves. The observations and analysis will provide a firm foundation for Cassini mission investigation of the rings. The HST and Arecibo data will not be supplanted by Cassini observations, because they have been taken under different viewing geometries and they sample very different parts of the scattering phase function of the particles. The investigator will relate the research to the educational life of Wellesley College, an undergraduate women's college with a history of success in educating women in science. This will be accomplished by supervising honors thesis students and undergraduate summer students, and by incorporating detailed examples of their research in both introductory and advanced courses. Dr. French will continue a successful outreach program by leading several-day seminars to about 25 K-12 teachers each year on the relationship between modern planetary science and terrestrial concerns such as global climate change and the consequences of giant impacts, and he will share the ongoing research under this project with teachers and the general public at a non-technical level. This award is made under the Research at Undergraduate Institutions program at NSF.***