Infrared Dark Clouds

红外黑云是大质量恒星和星团的诞生地。詹姆斯·杰克逊博士（波士顿大学）和他的团队将分析厘米、毫米、亚毫米和红外波长的大量观测结果，并辅以超大望远镜、澳大利亚望远镜国家设施22米望远镜、高原望远镜和射电天文研究所30米望远镜的新观测结果，以探索大质量原恒星演化中鲜为人知的过程。研究小组将于资助期内完成六项重点科研项目：(1)测量约100颗高质量原恒星的光谱能量分布，从而获得测热光度；(2)寻找高质量“前恒星”核心；(3)通过寻找围绕高质量恒星的星周盘来验证“竞争吸积”的说法；(4)验证年轻的O星实际上是以B星进入主序星，然后在成为主序O星的过程中继续吸积物质的观点。(5)测量大质量恒星形成云中的团块质量函数；(6)研究大质量原恒星核心的化学演化。当这个项目完成后，该团队将对了解大质量恒星形成的早期阶段鲜为人知的过程做出重大贡献，并将测试两个关键的理论观点：“竞争性吸积”和O型恒星首先作为吸积B型恒星进入主序的观点。杰克逊的团队在识别和表征红外乌云（irdc）方面处于领先地位。它们的特征大小（~几个秒差距）和质量（~不到1000个太阳质量）类似于猎户座和蛇夫座的星团形成分子团。然而，它们的低温表明它们处于较早的进化状态。毫米/亚毫米尘埃连续体的成像显示，irdc包含紧凑的核心，其大小（0.5秒差距）和质量（约100太阳质量）与与高质量原恒星相关的“热核心”相匹配。对这些核心的检查显示，大约三分之一的核心包含恒星形成的明确证据。在几个IRDC核心中嵌入的原恒星的大热光度表明它们目前正在形成大质量恒星。干涉观测显示，这些大质量恒星伴随着一些低质量的原恒星。因此，所有的初步证据都表明，irdc拥有大质量恒星和星团形成的最早阶段。除了将在该奖项下进行的研究外，该提案还将资助两名女研究生和一名女博士后的培训和教育。此外，波士顿大学天文系已与菲斯克大学（Fisk University）和范德比尔特大学（Vanderbilt University）达成合作协议，共同参与菲斯克-范德比尔特硕士-博士学位项目。桥梁项目，允许菲斯克学生在菲斯克攻读硕士学位，并保证进入范德比尔特大学和波士顿大学的博士课程。

Infrared Dark Clouds are the birthplaces of both high-mass stars and star clusters. Dr. James Jackson (Boston University) and his team will analyze a large suite of observations at centimeter, millimeter, sub-millimeter, and infrared wavelengths, supplemented by new observations at the Very Large Telescope, the Australian Telescope National Facility 22-m telescope, Plateau de Bure, and Institut de Radio Astronomie Millimétrique 30-m telescopes to explore the poorly understood processes at play in high-mass protostellar evolution. The team will complete six key science projects in this funding period: (1) Measuring the spectral energy distributions, and hence, bolometric luminosities, of ~100 high-mass protostars, (2) Searching for high-mass "pre-stellar" cores, (3) Testing the suggestion of "competitive accretion" by searching for circumstellar disks surrounding high mass stars, (4) Testing the idea that young O stars actually enter the main-sequence as B stars and then continue to accrete material on their way to becoming main-sequence O stars, (5) Measuring the clump mass function in high-mass star forming clouds, and (6) Studying the chemical evolution of high-mass protostellar cores. When this project is complete, the team will have made a significant contribution to the understanding of the poorly-known processes at play in the earliest stages of high-mass star formation and will have also tested two key theoretical ideas: "competitive accretion" and the idea that O stars first enter the main-sequence as accreting B stars.Dr. Jackson's group has led the way in identifying and characterizing Infrared Dark Clouds (IRDCs). Their characteristic sizes (~few parsecs) and masses (~few 1,000 solar-masses) resemble those of cluster-forming molecular clumps such as those in Orion and Ophichus. Their cold temperatures, however, suggest that they are in an earlier evolutionary state. Imaging of the mm/sub-mm dust continuum reveals that IRDCs contain compact cores, whose sizes (0.5 parsecs) and masses (~100 solar masses) match those of "hot cores" associated with high-mass protostars. An examination of these cores reveals that about 1/3 contain unambiguous evidence of star formation. The large bolometric luminosities of the embedded protostars within several IRDC cores show that they are currently forming high-mass stars. Interferometric observations reveal that these high-mass stars are accompanied by a number of lower mass protostars. All of the initial evidence, therefore, suggests that IRDCs host the earliest stages of the formation of high-mass stars and star clusters. In addition to the research that will be carried out under this award, this proposal will fund the training and education of two female graduate students and one female post-doctoral student. Moreover, the Boston University Astronomy Department has entered into a collaborative agreement with Fisk University, a historically black college, and Vanderbilt University to participate in the Fisk-Vanderbilt Masters-Ph.D. Bridge Program which allows Fisk students to pursue their Master's degrees at Fisk with guaranteed admission into Ph.D. programs at Vanderbilt and Boston University.