The Structure and Evolution of Molecular Clouds

分子云的结构和演化

• 批准号: 8918912
• 负责人: Leo Blitz
• 金额: $ 25.5万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-03-01 至 1993-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8918912&HistoricalAwards=false
• 关键词: Structure; Evolution; Molecular; Clouds

Dr. Blitz will investigate how the interstellar medium evolves from the diffuse state which is characteristic of most of its volume into the dense molecular state from which stars are formed. He will perform detailed observations of small molecular clouds without star formation which are found preferentially at high galactic latitudes, and which appear to have ages of less than 3,000,000 years. These young objects are imbedded in the atomic gas sheaths out of which the molecular clouds condensed, and Dr. Blitz hopes to identify the reasons why some parts of the atomic gas becomes molecular in these relatively simple clouds. He will make detailed comparative studies of the gas and dust associated with two giant molecular clouds that seem to be in different evolutionary states in order to understand how the structure of a giant molecular cloud evolves with time. Dr. Blitz will also explore the role of the molecular gas in the nuclei of Seyfert galaxies. In the fundamental stellar cycle, where the interstellar gas is collected into stars ultimately to be enriched with heavy elements and ejected back into interstellar space, one of the least well understood phases is the evolution of the diffuse gas into dense, star forming molecular clouds. We currently know very little about how the diffuse interstellar medium collects itself into giant molecular clouds and how these molecular clouds ultimately fragment into individual stars and clusters of stars. Dr. Blitz' research aims to illuminate the physical mechanisms by which the interstellar medium is prepared for the formation of new stars. That is, he seeks to understand how diffuse gas ultimately forms dense proto-stellar cores, the evolution of which as been aggressively investigated by many workers.

布利茨博士将研究星际介质是如何从其大部分体积的扩散状态演变成形成恒星的密集分子状态的。他将对没有恒星形成的小分子云进行详细的观察，这些云优先发现于银河系高纬度地区，其年龄似乎小于300万年。这些年轻的天体嵌在分子云凝聚的原子气体鞘中，布利茨博士希望找出为什么原子气体的某些部分在这些相对简单的云中变成分子的原因。他将对两个似乎处于不同进化状态的巨大分子云的气体和尘埃进行详细的比较研究，以了解巨大分子云的结构如何随着时间的推移而演变。布利茨博士还将探索塞弗特星系核中分子气体的作用。在基本的恒星周期中，星际气体被收集到恒星中，最终被重元素富集，并喷射回星际空间，其中一个最不为人所知的阶段是扩散气体演变成致密的恒星形成分子云。我们目前对漫射星际介质如何聚集成巨大的分子云以及这些分子云最终如何分裂成单个恒星和星团知之甚少。Blitz博士的研究旨在阐明星际介质为新恒星的形成所准备的物理机制。也就是说，他试图理解扩散气体最终如何形成致密的原恒星核心，许多研究人员对其演化进行了积极的研究。