Distances to high-velocity clouds

到高速云的距离

• 批准号: 0607508
• 负责人: Ronald Wilhelm
• 金额: $ 3.09万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0607508&HistoricalAwards=false
• 关键词: Distances; velocity; clouds

AST-0607508INSTITUTION: Texas Tech UniversityPI: Ronald WilhelmTITLE: Distances to High-Velocity CloudsABSTRACTDr. Ronald Wilhelm (Texas Tech University), along with collaborators Dr. Bastiaan Wakker (University of Wisconsin at Madison), Dr. Timothy Beers (Michigan State University), and Dr. Donald York (University of Chicago), will undertake a program to determine the distances to 14 so-called "high-velocity clouds" (HVCs), and "intermediate-velocity clouds" (IVCs). These are massive clouds of neutral hydrogen gas that are moving with velocities that are incompatible with simple models of galactic rotation. The goal will be accomplished by first determining the distances to "blue horizontal branch" (BHB) stars along the line of sight, from medium-resolution spectra, and then looking for interstellar absorption features from the clouds in high-resolution spectra. By determining which spectra reveal the signature of the clouds, and knowing the distances to the stars from which the spectra were derived, constraints on distances to the clouds can be obtained. Distances to these clouds remain one of the outstanding problems in Galactic astronomy, and resolution of the nature of these clouds will provide important constraints on models of galaxy formation and evolution.The work will have broad impact on various sub-fields of astronomy, particularly galaxy formation and evolution. Components of the program are self-contained, and well-suited for graduate and undergraduate research projects. Outreach activities will also be undertaken.

AST-0607508机构：德克萨斯理工大学PI：Ronald Wilhelm标题：到高速云的距离摘要博士。 Ronald Wilhelm（德克萨斯理工大学）与合作者 Bastiaan Wakker 博士（威斯康星大学麦迪逊分校）、Timothy Beers 博士（密歇根州立大学）和 Donald York 博士（芝加哥大学）将开展一项计划，以确定 14 个所谓的“高速云”(HVC) 和“中速云”(IVC) 的距离。 这些是大量的中性氢气云，其移动速度与简单的星系旋转模型不相容。该目标将通过首先根据中等分辨率光谱确定沿视线到“蓝色水平分支”（BHB）恒星的距离，然后在高分辨率光谱中寻找云层的星际吸收特征来实现。 通过确定哪些光谱揭示了云的特征，并了解了光谱所源自的恒星的距离，可以获得对云的距离的约束。与这些云的距离仍然是银河天文学中的突出问题之一，这些云的性质的解析将为星系形成和演化的模型提供重要的约束。这项工作将对天文学的各个子领域，特别是星系的形成和演化产生广泛的影响。该计划的组成部分是独立的，非常适合研究生和本科生的研究项目。 还将开展外展活动。