RUI: Emission Line Studies of High-Velocity Interstellar Clouds using the WHAM Spectrometer

RUI：使用 WHAM 光谱仪研究高速星际云的发射线

• 批准号: 0206349
• 负责人: Stephen Tufte
• 金额: $ 12.28万
• 依托单位: Lewis and Clark College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-15 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0206349&HistoricalAwards=false
• 关键词: RUI; Emission; Line; Studies; Velocity

AST 0206349TufteHigh-Velocity Clouds (HVCs) are an important component of the Milky Way's interstellar medium, covering a significant fraction of the sky and containing considerable mass and kinetic energy. HVCs are by definition peculiar; they are the material with velocities not explainable by the differential rotation of the galaxy. Despite over thirty-five years of study, their origin and nature remain a mystery. Proposed explanations of HVCs span a broad range. One picture envisions a galactic fountain. In this model, powerful supernova explosions in the disk of the galaxy vent hot material into regions high above the plane. The gas then cools, condenses into clouds, and then rains back down upon the disk. Another prominent model purports that the HVCs are dispersed throughout the Local Group of galaxies, the remnants of its creation. It appears that some of the high-velocity material was tidally torn from the Magallenic clouds, and now streams behind them in their orbit around our galaxy. Recent evidence suggests that one major complex of high-velocity material has low metallicity and is accreting onto the disk from high in the halo. This is especially interesting because such fresh fuel for star formation has long been required by models of the chemical evolution of the Galaxy. Current observational efforts to distinguish between these models will enhance present understandings of the formation of the Milky Way galaxy and its subsequent chemical evolution, as well as illuminate long debated issues concerning the connection of processes in the disk of our Galaxy to the halo. The vast majority of previous investigations of HVCs have used radio telescopes to study the 21- cm line, and thus only probe the neutral hydrogen present in the clouds. Dr. Stephen Tufte, at Lewis and Clark College, will investigate ionized material associated with HVCs by making measurements of optical emission lines using the Wisconsin H-Alpha Mapper (WHAM) Observatory. WHAM is a Fabry-Perot based spectroscopic instrument that sits atop Kitt Peak in Arizona and is completely remote-operable. The observations will take place from the principal investigator's laboratory on the campus of Lewis & Clark College, by way of the Internet. This project will measure the intensities of emission lines of hydrogen, nitrogen, sulfur, and oxygen from various HVCs. The observations will provide information on the locations and metal abundances of HVCs, will yield new insights into the nature of compact HVCs, and will reveal the physical conditions present in the clouds such as their temperature and ionization state. The principal investigator has already proven WHAM to be a uniquely powerful instrument for these studies. The new measurements have the ability to distinguish between the vastly different models that have been proposed to explain HVCs, and therefore significantly advance our understanding of their origin and nature. This award is made under the auspices of the Research in Undergraduate Institutions (RUI) program at NSF.***

AST 0206349塔夫特高速云（HVC）是银河系星际介质的重要组成部分，覆盖了相当大一部分的天空，并含有相当大的质量和动能。 HVC是一种特殊的物质，其速度不能用星系的差异旋转来解释。 尽管经过35年的研究，它们的起源和性质仍然是一个谜。 对HVC提出的解释范围很广。 其中一张图片设想了一个银河喷泉。在这个模型中，星系盘中强大的超新星爆炸将热物质排放到平面上方的区域。然后气体冷却，凝结成云，然后下雨回到磁盘上。 另一个著名的模型声称HVC分散在本星系群中，这是它创建的残余。 看来一些高速物质是从麦哲伦云中潮汐撕裂的，现在在它们后面绕着我们的银河系运行。 最近的证据表明，一个主要的高速物质复合体具有低金属含量，并从晕的高处吸积到盘上。 这是特别有趣的，因为这种新的燃料星星形成长期以来一直需要的模型的化学演变的星系。 目前的观测努力，以区分这些模型将提高目前的理解银河系的形成及其随后的化学演化，以及照亮长期争论的问题，有关的过程中的连接盘我们的银河系的晕。 绝大多数以前对HVC的研究都使用射电望远镜来研究21厘米线，因此只能探测云中存在的中性氢。 刘易斯和克拉克学院的斯蒂芬·塔夫特博士将通过使用威斯康星州H-阿尔法映射器（WHAM）天文台测量光学发射线来研究与HVC相关的电离物质。 WHAM是一种基于法布里-珀罗的光谱仪器，位于亚利桑那州的基特峰上，完全可以远程操作。 观测将通过互联网在刘易斯克拉克学院校园内的主要研究者实验室进行。 该项目将测量各种HVC的氢、氮、硫和氧的发射线强度。 这些观测将提供有关HVC的位置和金属丰度的信息，将对紧凑HVC的性质产生新的见解，并将揭示云中存在的物理条件，如它们的温度和电离状态。首席研究员已经证明了WHAM是这些研究的一个独特的强大工具。 新的测量有能力区分已经提出来解释HVC的截然不同的模型，因此大大推进了我们对其起源和性质的理解。 该奖项是在NSF的本科院校研究（RUI）计划的赞助下颁发的。