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arXiv 1201.1402astro-ph.GA
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红-暗云II中氨的甚大天线阵观测:内部动力学

Very Large Array Observations of Ammonia in Infrared-Dark Clouds II: Internal Kinematics

Sarah E. Ragan, Fabian Heitsch, Edwin A. Bergin, David Wilner

摘要:

红暗星云(IRDC)被认为是富星团的诞生地,因此包含了高质量恒星形成的最早阶段。我们使用绿岸望远镜(GBT)和甚大阵列(VLA)的氨(NH3)在六个IRDC地图测量其柱密度和温度结构(文件1),在这里,我们调查的运动学结构和能量含量。我们发现,IRDC整体显示有组织的速度场,只有局部的中断,由于嵌入式恒星的形成。在NH3排放中看到的局部效应不是高速流出,而是中等(几公里/秒)的线宽增加,表现出最大值附近或与中红外线发射跟踪原恒星一致。这些线宽的增强可能是由于入流或(隐藏在NH3排放)流出。不仅是动能含量不足以支持IRDC对崩溃,而且空间能量分布是不一致的一个方案的湍流云支持。我们的结论是,在我们的样本中的IRDCs的速度签名是由于积极的崩溃和分裂,在某些情况下,从恒星的局部反馈增强。

英文摘要:

Infrared-dark clouds (IRDCs) are believed to be the birthplaces of rich clusters and thus contain the earliest phases of high-mass star formation. We use the Green Bank Telescope (GBT) and Very Large Array (VLA) maps of ammonia (NH3) in six IRDCs to measure their column density and temperature structure (Paper 1), and here, we investigate the kinematic structure and energy content. We find that IRDCs overall display organized velocity fields, with only localized disruptions due to embedded star formation. The local effects seen in NH3 emission are not high velocity outflows but rather moderate (few km/s) increases in the line width that exhibit maxima near or coincident with the mid-infrared emission tracing protostars. These line width enhancements could be the result of infall or (hidden in NH3 emission) outflow. Not only is the kinetic energy content insufficient to support the IRDCs against collapse, but also the spatial energy distribution is inconsistent with a scenario of turbulent cloud support. We conclude that the velocity signatures of the IRDCs in our sample are due to active collapse and fragmentation, in some cases augmented by local feedback from stars.

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