Infrared Dark Clouds

红外暗云是大质量恒星和星星团的诞生地。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，并辅以甚大望远镜，澳大利亚望远镜国家设施22米望远镜，Plateau de Bure，和射电天文学研究所的毫米30米望远镜，以探索在大质量原恒星演化中鲜为人知的过程。 该团队将在此资助期内完成六个关键科学项目：（1）测量光谱能量分布，从而测量大约100颗大质量原恒星的辐射热光度，（2）寻找大质量“前恒星”核心，（3）通过寻找围绕大质量恒星的星周盘来检验“竞争吸积”的建议，（4）验证年轻O星实际上作为B星进入主序星，然后在成为主序星的过程中继续吸积物质的想法，（5）测量高质量星星形成云的团块质量函数，（6）研究高质量原恒星核的化学演化。 当这个项目完成时，该团队将对理解在大质量星星形成的最早阶段中起作用的鲜为人知的过程做出重大贡献，并且还将测试两个关键的理论思想：“竞争性吸积”和O星首先进入主序星的吸积B星的想法。杰克逊博士的小组在识别和描述红外暗云（IRDC）。 它们的特征尺寸（约几个秒差距）和质量（约1,000个太阳质量）类似于猎户座和蛇腹星座中的星团形成分子团。然而，它们的低温表明它们处于更早的进化状态。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1/3包含星星形成的明确证据。在IRDC的几个核心中，嵌入的原恒星的大辐射热光度显示它们目前正在形成高质量恒星。干涉测量观测显示，这些高质量恒星伴随着一些质量较低的原恒星。因此，所有的初步证据都表明，IRDC是高质量恒星和星星团形成的最早阶段。 除了将在该奖项下开展的研究外，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，波士顿大学天文系还与历史上的黑人学院菲斯克大学和范德比尔特大学达成合作协议，参加菲斯克-范德比尔特硕士-博士学位。桥梁计划，允许菲斯克学生在菲斯克攻读硕士学位，并保证进入博士学位。范德比尔特和波士顿大学的项目。

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.