Southern Serpents: The Internal Structure of Interstellar Filaments in the Fourth-Quadrant of the Milky Way

几乎所有恒星的诞生地都在银河系盘面上的星际分子云中。先前对银盘的观测表明，许多这样的云在很大的物理尺度上都是丝状的。虽然天文学家同意恒星是在星际云最密集的区域形成的，但他们目前还不了解星际细丝对恒星形成过程的重要性。测量星际云三维结构的唯一方法是通过光谱无线电观测。研究人员将使用三种光谱调查来共同探测银河系南部平面内星际细丝的原子和分子内部结构。主要的研究目标是1)表征细丝的速度结构，并将其与数值模型进行比较，以得出有关其寿命，稳定性和恒星形成效率的结论；2)利用原子和分子观察的高阶统计量追踪细丝的湍流结构。研究者自愿加入威斯康星大学麦迪逊分校麦克奈尔学者计划，担任科学技术工程和数学（STEM）专业顾问，旨在为第一代，低收入和少数民族本科生准备研究生院及以后。本研究亦将为本科生提供训练及辅导机会。如果丝状云是唯一密度大到足以形成恒星的结构，那么银河系恒星形成的理论就需要关注丝状分子云的形成和演化，包括发生原始恒星活动的丝状亚结构。该研究项目将通过对其分子气体和原子外壳的光谱观测，直接识别和表征星际细丝，从而做出贡献。主要的数据产品之一将是细丝的目录，以及对它们进行的动力学研究的结果。这将允许未来研究原恒星活动与丝状结构的关系。

The birthplace of nearly all stars lies within the interstellar molecular clouds that reside in the disk of the Milky Way Galaxy. Previous observations of the Galactic disk suggest that many of these clouds are filamentary over a wide range of physical scales. While astronomers agree that stars form within the densest regions of interstellar clouds, they currently do not understand the importance of interstellar filaments for the process of star formation. The only way to measure the three-dimensional structure of interstellar clouds is through spectroscopic radio observations. The investigator will use three spectroscopic surveys in concert to probe both the atomic and molecular internal structure of interstellar filaments within the southern Galactic plane. The main research objectives are to 1) characterize the velocity structure of the filaments and compare this to numerical models to draw conclusions about their lifetimes, stability and star-formation efficiencies, 2) trace the turbulent structure of the filaments using higher order statistics on both the atomic and molecular observations.The investigator volunteers with the University of Wisconsin-Madison McNair Scholars Program as a Science Technology Engineering and Mathematics (STEM) Professional Advisor aimed at preparing first-generation, low-income, and minority undergraduates for graduate school and beyond. This research will also provide training and mentoring opportunities for undergraduate students.If filamentary clouds are the only structures with densities large enough to form stars, then the theory of Galactic star formation needs to be focused on the formation and evolution of filamentary molecular clouds, including filamentary sub-structures where proto-stellar activity occurs. This research project will make a contribution by directly identifying and characterizing interstellar filaments through spectroscopic observations of both their molecular gas and atomic envelopes. One of the main data products will be a catalog of filaments, along with the results from the dynamical studies done on them. This will allow future research on where proto-stellar activity resides in relation to filamentary structure.