Watching the Birth of Super Star Clusters

AST0307950PI：Jean TurnerInstution：加州大学洛杉矶分校球状星团是现代天文学最大的谜团之一。球状星团是包含数十万颗恒星的大型球状星团。在银河系中，球状星团的年龄都超过100亿年。然而，我们的银河系直到今天仍在形成单个恒星和小星团；为什么不形成球状星团呢？多年来，人们一直认为，早期宇宙需要特殊的条件才能形成大型星系团。最近，在附近的星系中发现了年轻的“超级星团”，它们被认为是球状星团的前身。本地宇宙中年轻的超级星团的存在告诉我们，大型星团可以在“现在”的宇宙中形成，也就是在过去的几百万年内形成。这也意味着现在有可能真正观看球状星团的诞生，并试图解开为什么银河系中的球状星团都是老的这个谜题。特纳将研究非常年轻的超级星团，这些星团如此年轻，以至于它们仍然被埋在它们出生的气体云中。她将使用非常大的阵列来拍摄厘米波长的年轻超级星团相关的气态星云，并获得围绕星团的热气云的准确位置和清晰图像。在凯克望远镜上的观测将产生气云中尘埃发出的红外辐射的亚角秒分辨率图像，以确定年轻星团的能量输出，红外光谱将用于确定气体的多普勒频移速度，由此可以确定气云的运动、动力学和演化。这些星系团是否会产生超风，从而可能影响到它们周围的星系？这些气体云的什么性质--密度、角动量？--可以解释超星团形成和银河系恒星形成之间的差异？有证据表明这些年轻的星团已经解体了吗？这也许可以解释为什么银河系中没有年轻的超级星团？这项正在进行的研究项目的结果将通过学术期刊上的文章、科学演讲和万维网上的帖子广泛传播给天文学家和物理学家。特纳博士和她的同事将向提出要求的天文学家提供减少的数据和图像，并维护网络上最受欢迎的无线电和红外图像。她和她的合作者和学生还将通过热门演讲、热门文章、新闻发布会、新闻稿和网络材料向公众展示图像和结果。这项研究项目的一个主要组成部分是培养年轻的物理学家和天体物理学家，包括研究生和本科生。***

AST 0307950PI: Jean TurnerINSTITUTION: University of California, Los Angeles Globular clusters present one of the great mysteries of modern astronomy. Globular clusters are large, spherical clusters containing hundreds of thousands of stars. In the Milky Way, globular clusters are all older than 10 billion years. Yet our Galaxy continues to form individual stars and small star clusters to the present day; why not globular clusters? For years it was believed that special conditions in the early universe were required for the formation of large clusters. Recently young "super star clusters", believed to be the precursors to globular clusters, have been discovered in nearby galaxies. The presence of young super star clusters in the local universe tells us that large clusters CAN form in the "present" universe, that is, within the past few million years. It also means that it is now possible to actually watch globular clusters being born, and to attempt to solve the puzzle of why globular clusters in the Milky Way are all old.Dr. Turner will study super star clusters that are very young, so young that they are still buried in their natal gas clouds. She will use the Very Large Array to image gaseous nebulae associated with young super star clusters at centimeter wavelengths, and to obtain precise locations and sharp images of the hot gas clouds that surround the clusters. Observations on the Keck Telescope will yield subarcsecond-resolution images of the infrared emission from dust in the gas clouds, to determine the energy outputs of the young clusters, and infrared spectra will be used to determine Doppler-shifted velocities for the gas, from which the motions, dynamics, and evolution of the gas clouds can be determined. Do these clusters cause superwinds, which might affect the galaxy around them? What properties of these gas clouds -density, angular momentum?-might explain the differences between super star cluster formation and star formation in the Milky Way? Is there evidence for the dissolution of these young clusters, which might explain why there are no young super star clusters in the Milky Way?The results of this ongoing research project will be widely disseminated to astronomers and physicists through articles in scholarly journals, scientific talks, and postings on the World Wide Web. Dr. Turner and her colleagues will provide reduced data and images to astronomers who request them and maintain the most popular radio and infrared images on the web. She and her collaborators and students will also reach the public with the presentation of images and results through popular talks, popular articles, press conferences, press releases, and web materials. A major component of this research project is the training of young physicists and astrophysicists, both graduate and undergraduate students. ***