Collaborative Research: Dust, Gas, and Star Formation: Synthesizing 20 Years of Radio, Millimeter, and Infrared Surveys

星系通过将星际气体转化为新一代的恒星而成长。这个过程的一个主要步骤是将低密度的原子气体转化为寒冷、密集的恒星形成云。星际尘埃通过保护气体免受破坏性紫外线辐射和促进化学反应来控制这一过程。尘埃和冷气体的丰度取决于星系中的局部环境，但这种依赖的性质仍然在非常基本的层面上存在争议。这个项目将通过绘制尘埃、中性星际气体（弥漫的原子气体和冷的、致密的分子气体）和附近星系样本的局部条件，来测试相互竞争的假设，这些样本比以前的研究中使用的样本大十倍。研究人员将利用这些观测数据来回答关于星系中气体和恒星形成的两个问题。第一个问题是，是什么决定了形成恒星的低温气体的数量？第二个问题是什么决定了尘埃的丰度？这两个交织在一起的问题对于理解星系如何随时间增长和变化至关重要。研究人员将组装下一代星系中尘埃和气体分布的数据库。为了做到这一点，他们将把美国国家科学基金会资助的甚大阵列对氢原子（HI）的新观测和档案观测与赫歇尔航天器对星际尘埃分布和性质的测量结合起来。通过这样的观测，他们将增加一个数量级的星系样本。以这种方式研究的星系数量的一个数量级的增加，将把这个领域推进到一个新的统计假设检验制度，这是理解星系中气体物理学的一个潜在的变革步骤。观测数据库将在互联网上与其他天文学家和公众共享。研究人员将在Zooniverse项目的基础上与公众分享他们的观察结果。Zooniverse是一个允许公众查看和分类科学观察的互联网工具。有了这个工具，公众既可以欣赏观察结果，也可以帮助研究。研究人员计划创建“HI洞项目”，在这个项目中，志愿者公民科学家将在真实和模拟星系的气体星际介质中识别巨大的洞。

Galaxies grow by converting interstellar gas into new generations of stars. A main step in that process is the conversion of low-density, atomic gas into cold, dense, star-forming clouds. Interstellar dust controls this process by shielding gas from destructive ultraviolet radiation and promoting chemical reactions. The abundance of both dust and cold gas depend on local environment in a galaxy, but the nature of this dependence is still debated at a very basic level. This project will test competing hypotheses for what sets the amount of dust and cold gas in galaxies by mapping dust, neutral interstellar gas (diffuse atomic gas and cold, dense molecular gas), and local conditions in a sample of nearby galaxies ten times larger than those used in previous studies. The investigators will use these observations database to answer two questions about gas and star formation in galaxies. The first question is what sets the amount of cold, star-forming gas? The second question is what determines the abundance of dust? These two intertwined questions are critical to understand how galaxies grow and change over time.The investigators will assemble the next generation database of dust and gas distributions in galaxies. To do this, they will combine new and archival observations of atomic hydrogen (HI) from the NSF-funded Very Large Array with Herschel spacecraft measurements of the distribution and properties of interstellar dust. They will increase, by an order of magnitude, the sample of galaxies with such observations. An order of magnitude increase in the set of galaxies studied in this way will advance the field into a new regime of statistical hypothesis testing, a potentially transformative step in understanding the physics of gas in galaxies.The observing database will be shared on the internet with other astronomers and also the public. The investigators will build on the Zooniverse project to share their observations with the public. Zooniverse is an internet tool that allows the public to view and classify scientific observations. With this tool, the public can both appreciate the observations and aid in the research. The investigators plan to create 'the HI Holes Project', in which volunteer citizen scientists will identify giant holes in the gaseous interstellar medium of real and simulated galaxies.