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arXiv 0909.0382astro-ph.GAastro-ph.CO
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大麦云中的分子和原子气体II。CO和HI的三维相关性

Molecular and Atomic Gas in the Large Magellanic Cloud II. Three-dimensional Correlation between CO and HI

Y. Fukui, A. Kawamura, T. Wong, M. Murai, H. Iritani, N. Mizuno, Y. Mizuno, T. Onishi, A. Hughes, J. Ott, E. Muller, L. Staveley-Smith, S. Kim

摘要:

我们在三维空间(即除了两个空间轴外还包括一个速度轴)比较了大麦云(LMC)中的CO J =(1-0)和HI辐射,目的是阐明巨分子云(GMC)与其周围HI气体之间的物理联系。CO J =1-0数据集来自第二次NANTEN CO巡天,HI数据集来自合并的澳大利亚望远镜紧凑阵列(ATCA)和帕克斯望远镜巡天。我们分析的主要发现是:1)GMC与HI发射的包络有关,2)在GMC中,[平均CO强度]与[平均HI强度]^[1.1+-0.1]成正比,3)HI强度随着GMC中恒星形成活动的增加而增加,从I型到III型。对与GMC有关的HI包线的分析表明,它们的平均线宽为14 km s-1,包线中的平均密度为10 cm-3。我们认为,HI信封引力约束的GMC。这些研究结果是一致的,通过HI吸积在0.05 Msun/年的吸积率超过10万年的时间尺度的GMCs的质量的持续增加。在GMC演化的最后阶段,GMC的生长通过耗散电离和/或星风破坏而终止。

英文摘要:

We compare the CO J =(1-0) and HI emission in the Large Magellanic Cloud (LMC) in three dimensions, i.e. including a velocity axis in addition to the two spatial axes, with the aim of elucidating the physical connection between giant molecular clouds (GMCs) and their surrounding HI gas. The CO J =1-0 dataset is from the second NANTEN CO survey and the HI dataset is from the merged Australia Telescope Compact Array (ATCA) and Parkes Telescope surveys. The major findings of our analysis are: 1) GMCs are associated with an envelope of HI emission, 2) in GMCs [average CO intensity] is proportional to [average HI intensity]^[1.1+-0.1] and 3) the HI intensity tends to increase with the star formation activity within GMCs, from Type I to Type III. An analysis of the HI envelopes associated with GMCs shows that their average linewidth is 14 km s-1 and the mean density in the envelope is 10 cm-3. We argue that the HI envelopes are gravitationally bound by GMCs. These findings are consistent with a continual increase in the mass of GMCs via HI accretion at an accretion rate of 0.05 Msun/yr over a time scale of 10 Myr. The growth of GMCs is terminated via dissipative ionization and/or stellar-wind disruption in the final stage of GMC evolution.

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