From Io's Atmosphere to the Plasma Torus

该项目的目的是通过对土星环视亮度随环经度的剧烈变化的全面调查，加深对土星环动力学和结构的了解。这种方位亮度的不对称通常归因于引力尾迹——在相互引力作用下，环状粒子团试图吸积，但被土星挫败了。强烈的潮汐影响。韦尔斯利学院（Wellesley College）的理查德·弗伦奇（Richard French）博士将把哈勃太空望远镜（Hubble Space Telescope）拍摄的数百幅丰富图像和阿雷西博天文台（Arecibo Observatory）拍摄的多幅雷达图像与引力尾迹动力学模型的预测结果进行比较。环的详细结构的n体模拟，以及由此产生的引力尾迹，显示出环的详细特性，如颗粒大小的分布、表面质量密度和粒子间碰撞的弹性，非常依赖于环的详细特性。由于尚未完全了解的原因，造成的不对称强度在各环之间也有很大差异。例如，这项工作将量化新发现的B环内部的方位不对称性。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、高质量的数据集（10年的HST观测和几年的阿雷西博雷达结果）和对光环的真实物理描述。这项研究将解决环动力学的基本特征，如引力不稳定性，以及环粒子本身的特性。这些观测和分析将为卡西尼号对土星环的调查提供坚实的基础。HST和阿雷西博的数据不会被卡西尼号的观测所取代，因为它们是在不同的观测几何形状下拍摄的，它们对粒子散射相函数的不同部分进行了采样。研究者将把这项研究与韦尔斯利学院的教育生活联系起来，韦尔斯利学院是一所本科女子学院，在教育女性科学方面有着成功的历史。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示例来完成。弗兰奇博士将继续成功的外展计划，每年为大约25名K-12教师举办为期几天的研讨会，讨论现代行星科学与地球问题（如全球气候变化和巨大影响的后果）之间的关系，他将在非技术层面上与教师和公众分享该项目下正在进行的研究。该奖项由美国国家科学基金会本科院校研究项目授予

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.***