Comprehensive Study of Atomic & Molecular Gas in Taurus: Evolution of the Interstellar Medium and Star Formation

AST 0407019 goldsmithdr。保罗·戈德史密斯将对金牛座分子云复合体进行一项重大研究。它将产生迄今为止在12CO和13CO中获得的最大的分子云图像。该项目还将在100平方度区域内生成第一张完全采样的原子氢高角分辨率地图。原子和分子数据集的结合，将与金牛座尘埃分布和年轻恒星的现有数据相结合，为研究分子云和恒星形成生命周期的关键方面提供一个独特的工具。由于射电天文成像技术的最新发展，获取数据来解决这些重要问题才有可能。分子图谱将使用五校射电天文台13.7m望远镜和32元红杉焦平面阵列获得，观测时间已经分配。利用305米阿雷西博望远镜和7元双偏振ALFA焦平面阵列系统获得HI数据。在这些仪器的可用性提供了一个数量级的增加测绘速度之前，在超过100:1的比尺范围内，用对结构敏感所需的角分辨率来覆盖所需的立体角是不现实的。极大增强的功能允许该项目解决以下关键问题。1. 金牛座的原子和分子成分之间的关系，包括该地区的进化史，将通过比较氢的发射和吸收谱线轮廓和柱密度，并通过其残余原子气体含量确定云核的年龄来解决；2. Goldsmith博士及其合作者将根据主成分分析（Principal Component Analysis）确定湍流支持的临界尺度，研究湍流在黑云复合体中的作用——包括原子/分子跃迁和新星形成过程中的作用；3. 将确定恒星形成的关键参数，包括柱密度和/或密度的阈值，分子云和恒星之间的关联，以及恒星形成中大规模过程与局部效应的作用；4. 年轻恒星对分子云和随后的恒星形成的影响将通过对分子流出物、它们返回分子云的能量以及它们对云结构的影响进行全面普查来评估。这项工作将对天体物理学和恒星形成研究的广泛领域产生影响，特别是(1)原子和分子云流体动力学的数值模拟，包括这两个关键阶段之间的转变；(2)基于气相反应和氢分子颗粒表面形成的时变天体化学；(3)分子云的整体能量学，包括湍流的耗散和再生。这项工作将把研究和教学结合起来。数据的各个部分将是理想的调查本科生。由于公众对类太阳恒星的形成非常感兴趣，而且这种测绘项目确实产生了人们可以联系的图像，因此它非常适合于演讲和成为当地科学教育设施正在考虑的展览的焦点。

AST 0407019GoldsmithDr. Paul Goldsmith will carry out a major study of the Taurus molecular cloud complex. It will result in the largest images in 12CO and 13CO of a molecular cloud yet obtained. This project will also produce the first fully sampled high angular resolution map of atomic hydrogen in the 100 square degree region. The combination of the atomic and molecular data sets will, in conjunction with existing data on the dust distribution and young stars in Taurus, provide a unique tool for studying key aspects of the life cycle of molecular clouds and star formation.Acquiring the data to address these important questions is only possible due to recent developments in radio astronomical imaging technology. The molecular maps will be obtained using the Five College Radio Astronomy Observatory 13.7m telescope and 32 element Sequoia focal plane array: observing time has already been allocated. The HI data will be obtained using the 305m Arecibo telescope and the 7 element dual polarization ALFA focal plane array system. Prior to the availability of these instruments which provide an order of magnitude increase inmapping speed, it was not realistic to cover the required solid angle with the angular resolution needed to be sensitive to structure over a range of scales exceeding 100:1. The greatly enhanced capability permits this project to address the following key questions. 1. The relationship between the atomic and molecular components of Taurus, including the evolutionary history of the region, will be addressed by comparing the hydrogen emission and absorption line profilesand column densities, and by determining the ages of cloud cores from their residual atomic gas content; 2. The role of turbulence in dark cloud complexes -- both in the atomic/molecular transition and in the formation of new stars -- will be studied by the Dr. Goldsmith and collaborators through identification of critical scales for turbulent support based on Principal Component Analysis; 3. Critical parameters for star formation, including the threshold of column density and/or density, the association between molecular clouds and stars, and the role of large scale processes versus local effects in star formation will be identified; 4. The impact of young stars on molecular clouds and subsequent star formation will be evaluated by carrying out a complete census of molecular outflows, the energy that they have returned to molecular clouds, and their effect on cloud structure. This work will have an impact on a wide range of areas in astrophysics and star formation research, especially (1) numerical simulations of atomic and molecular cloud hydrodynamics including the transition between these two key phases; (2) time dependent astrochemistry based on gas phase reactions and grain surface formation of molecular hydrogen; (3) the overall energetics of molecular clouds including dissipation and regeneration of turbulence. This work will integrate research and teaching. Various portions of the data will be ideal for investigation by undergraduate students. Inasmuch as the formation of solar type stars is of considerable interest to the public, and that this kind of mapping project really does produce images to which people can relate, it is ideally suited for both talks and to be the focus of exhibits being contemplated for local science education facilities.