Density structure of molecular clouds as a probe of the ISM physics

分子云的密度结构作为 ISM 物理学的探针

• 批准号: 203356129
• 负责人: Jouni Kainulainen, Ph.D.
• 金额: --
• 依托单位: Max-Planck-Institut für Astronomie (MPIA)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203356129?language=en
• 关键词: Density; structure; molecular; clouds; probe

Understanding the physical processes that control the life-cycle of the interstellar medium (ISM) is one of the key themes in the astrophysics of galaxies today. This importance derives from the role of the ISM as the birthplace of new stars, and consequently, as an indivisible constituent of galaxy evolution. Exactly how the conversion of the ISM to stars takes place is intricately linked to the structure of the cold, molecular phase of the ISM. Indeed, we know that the true formation sites of stars are the strong density enhancements in the interstellar molecular clouds. Whatever processes control the evolution of these density enhancements very concretely control the gas-to-stars conversion. However, our current picture of the molecular cloud structure formation has a fundamental caveat: it is based almost entirely on observations of nearby, low-mass molecular clouds that form only low-mass stars. This is because only in nearby clouds, traditional observation techniques can reach an adequately high spatial resolution and sensitivity. Yet, it is the high-mass molecular clouds in which most stars form, and it is the high-mass stars and star-clusters that impact the ISM of galaxies most. Based on the work done during the first ISM-SPP funding period, I present a program that will fill the gap in our understanding of the internal structure of massive molecular clouds. We have developed a new observational technique that provides an unparalleled view of the structure of massive molecular clouds. We also have developed a technique with which such high-fidelity data can be used to study one of the most fundamental measures of the molecular cloud structure, the probability density function of their volume densities. With this program, the full potential of these tools will be put into use. We will derive high-fidelity column density data for a large number of massive molecular clouds, and build an unprecedented census of their internal structure. We will also use the data of recent molecular line surveys to trace the kinematic properties of the clouds. As an integral part of the program, we will connect the obtained observational picture to state-of-the-art, galaxy-scale numerical simulations. This approach allows us to address keyquestions in the field: What physics drive the structure formation in massive molecular clouds? How do high-mass clouds fragment? How does the structure of high-mass clouds gives rise to the star formation within? Are these processes different in low-mass and high-mass molecular clouds? Most crucially, the program allows us to build a view of the molecular cloud structure, and of the processes that control this structure, over the entire mass range of molecular clouds in the ISM.

了解控制星际培养基（ISM）的生命周期的物理过程是当今星体物理学的关键主题之一。这种重要性源自ISM作为新恒星的发源地的作用，因此是银河进化的不可分割的组成部分。确切地与ISM的冷，分子相结合的结构错综复杂地联系在一起。确实，我们知道恒星的真实地层位点是星际分子云中强密度的增强。无论哪种过程控制这些密度增强的演变，都会非常具体地控制气体对明星的转化。但是，我们目前对分子云结构形成的情况有一个基本的警告：它几乎完全基于对仅形成低质量恒星的附近低质量分子云的观察。这是因为只有在附近的云中，传统的观察技术才能达到足够高的空间分辨率和灵敏度。然而，这是大多数恒星形成的高质量分子云，而高质量的恒星和恒星群会影响星系的ISM。根据在第一个ISM-SPP资金期间所做的工作，我提出了一个程序，该程序将填补我们对大型分子云的内部结构的差距。我们已经开发了一种新的观察技术，该技术提供了无与伦比的巨大分子云结构的视野。我们还开发了一种技术，可以使用这种高保真数据来研究分子云结构的最基本度量之一，即其体积密度的概率密度函数。有了这个程序，这些工具的全部潜力将被利用。我们将为大量大量分子云提供高保真柱密度数据，并建立其内部结构前所未有的人口普查。我们还将使用最近的分子线调查的数据来追踪云的运动学特性。作为该程序不可或缺的一部分，我们将将所获得的观测图像连接到最新的Galaxy尺度数值模拟。这种方法使我们能够解决现场中的钥匙问题：哪种物理驱动大量分子云中的结构形成？高质量云如何碎片？高质量云的结构如何产生内部的恒星形成？这些过程在低质量和高质量分子云中是否有所不同？最关键的是，该程序使我们能够在ISM中的整个分子云中构建分子云结构以及控制该结构的过程的视图。