Formation of Galactic Massive Stars and Star Clusters

这项工作建立在博洛卡姆星系平面调查(BGPS)的基础上，首席研究员之前曾得到美国国家科学基金会的支持。现在，在那次调查中发现的最大质量的原始星系团被用先进的观测设备进行了研究，从近红外到厘米波长的角度分辨率尽可能高。这些观测被用来了解银河系和其他星系中大质量恒星和星团是如何形成的。了解大质量恒星的形成是全面了解银河系结构和演化的必要组成部分。关于大质量恒星的知识在天文学的其他领域也很重要，例如，这些恒星通过核合成产生重元素，它们在活动星系核的增长中发挥作用。人们提出了两种主要的大质量恒星形成机制：相互作用的团簇的竞争吸积和高压环境下大质量核心的孤立坍塌。在这项工作中，如果大质量恒星形成孤立的系统，或者如果它们与兄弟恒星相互作用，并竞争从它们的母星团共生，它就被解决了。这项工作还有助于更好地理解反馈的作用，如外流和紫外线辐射对星团中后续恒星形成的影响。这项工作解决的其他问题包括：是什么决定了恒星形成的数量和恒星质量上限，以及什么条件导致非束缚OB关联与引力束缚星团。观测以高空间分辨率针对银河系最大质量的恒星形成区域，并将使用阿帕奇点天文台(APO)、扩展甚大阵列(EVLA)、联合毫米波天文学研究阵列(CARMA)、阿塔卡马大毫米阵列(ALMA)和双子座等望远镜上的自适应光学系统。已经有了大量的数据，该计划的很大一部分是用最先进的仪器和望远镜进行新的观测。其中几种工具是在国家科学基金会的资助下开发出来的。目标清单包括最近的两个活跃的高光度源，猎户座A和仙王座A，在那里已经证明了几种观测方法，并发现了显著的动力学相互作用的证据。这个项目涉及一个庞大的研究团队，以加强学术网络基础设施。作为这个项目的一部分，两名研究生正在写他们的博士论文，有机会让更多的研究生和本科生参与其中。研究生也将积极参与外展活动。作为这项工作的一部分，首席研究员S在博尔德的索默-博施天文台实施了一个本科生研究项目。该项目向科罗拉多大学的物理学和天文学本科生介绍了对最近恒星形成区域的年轻恒星的光度监测，这些区域足够透明，可以用24英寸的SBO望远镜在可见光波长下进行观测。预计这个项目将拍摄到令人惊叹的图像，这些图像将在菲斯克天文馆和丹佛自然与科学博物馆的流行演讲中使用，并将通过互联网和菲斯克天文馆传播。

This work builds upon the Bolocam Galactic Plane Survey (BGPS) for which the principal investigator had previous support from the NSF. Now the most massive proto-cluster clumps found in that survey are investigated with advanced observational facilities at the highest possible angular resolution from near-infrared through cm-wavelengths These observations are used to learn how massive stars and clusters form in the Milky Way as well as in other galaxies. Understanding the formation of massive stars is a necessary piece in a complete picture of galactic structure and evolution. The knowledge about massive stars is also important in other areas of astronomy, e.g., these stars produce heavy elements through nucleosynthesis, and they play a role in the growth of Active Galactic Nuclei. Two major mechanisms have been proposed for massive star formation: Competitive accretion from a cluster of interacting clumps and isolated collapse of massive cores in a high pressure environment. In this work it is addressed if massive stars form as isolated systems, or if they interact with sibling stars and compete to accrete from their parent clump. This work also leads to a better understanding of the role of feedback such as outflows and UV radiation on subsequent star formation in the clump. Other questions addressed by this work are what determines the number of stars formed and the upper stellar mass-limit, and what conditions lead to unbound OB associations versus gravitationally bound clusters.The observations target the Galaxy's most massive star-forming regions at high spatial resolution and will use the Apache Point Observatory (APO), the Expanded Very Large Array (EVLA), the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), the Atacama Large Millimeter Array (ALMA) and adaptive optics on telescopes such as Gemini. A large amount of data is already available and a significant part of the program is for new observations with the most advanced instruments and telescopes. Several of these instruments have been developed with funding from the NSF. The target list includes the two nearest active, high-luminosity sources, Orion A and Cepheus A, where several of the observing methods have been demonstrated and evidence of significant dynamical interactions has been discovered.This project involves a large team of researchers which strengthens the academic network infrastructure. Two graduate students work on their doctoral theses as part of this project, and there are opportunities for more graduate- and undergraduate student participation. The graduate students will also be actively involved in the outreach activities.A s part of this work the principal investigator implements an undergraduate research program at Sommer-Bausch Observatory (SBO) in Boulder. This introduces physics and astronomy undergraduate students from the University of Colorado to photometric monitoring of young stars in the closest star-forming regions that are sufficiently un-obscured to permit observations at visual wavelengths with the 24" SBO telescope. Stunning images are expected from this project which find use in popular talks at Fiske Planetarium and the Denver Museum of Nature and Science, and which are to be disseminated via the internet and Fiske planetarium.