Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined from J = 3-2 and J = 1-0 Transitions of CO-猫眼课题宝

DOI：

10.1086/524038

发表时间：

2007-10

期刊：

The Astrophysical Journal Supplement Series

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

T. Minamidani;N. Mizuno;Y. Mizuno;A. Kawamura;T. Onishi;T. Hasegawa;K. Tatematsu;Masafumi Ikeda;Y. Moriguchi;N. Yamaguchi;J. Ott;T. Wong;E. Muller;J. Pineda;A. Hughes;L. Staveley-Smith;U. Klein;A. Mizuno;S. Nikolić;R. Booth;A. Heikkilä;L. Nyman;M. Lerner;G. Garay;Sungeun Kim;M. Fujishita;T. Kawase;M. Rubio;Y. Fukui

我们利用 ASTE 10 m 亚毫米望远镜对大麦哲伦星云 (LMC) 中的 6 个巨分子云 (GMC) 进行了亚毫米 12CO(J = 3–2) 观测，空间分辨率为 5 pc，灵敏度非常高。我们在 GMC 中识别出了 32 个分子团，并揭示了 n(H2) ∼ 103–105 cm−3 和 Tkin ∼ 60 K 的温暖而致密的分子气体的重要细节。这些数据与 12CO(J = 1–0) 和 13CO(J = 1–0) 结果相结合，并与 LVG 计算进行比较。结果表明，我们检测到的团块从冷（~10-30 K）到暖（≳30-200 K）连续分布，而暖团块从较不稠密（~103 cm−3）到稠密（~103.5-105 cm−3）分布。我们发现 12CO(J = 3–2) 与 12CO(J = 1–0) 排放的比率对局部 Hα 通量敏感且与之密切相关。我们推断团块特性的差异代表了 GMC 在导致恒星形成的密度增加方面的进化序列。 I 型和 II 型 GMC（分别为无星 GMC 和仅具有 H II 区域的 GMC）处于恒星形成的年轻阶段，其中密度尚未高到足以显示活跃的恒星形成，而 III 型 GMC（具有 H II 区域和年轻星团的 GMC）代表平均密度增加且 GMC 正在形成大质量恒星的后期阶段。与 Hα 通量相关的高动力学温度表明 FUV 加热在 LMC 的分子气体中占主导地位。

We have carried out submillimeter 12CO(J = 3–2) observations of six giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) with the ASTE 10 m submillimeter telescope at a spatial resolution of 5 pc and very high sensitivity. We have identified 32 molecular clumps in the GMCs and revealed significant details of the warm and dense molecular gas with n(H2) ∼ 103–105 cm−3 and Tkin ∼ 60 K. These data are combined with 12CO(J = 1–0) and 13CO(J = 1–0) results and compared with LVG calculations. The results indicate that clumps that we detected are distributed continuously from cool (~10-30 K) to warm (≳30-200 K), and warm clumps are distributed from less dense (~103 cm−3) to dense (~103.5-105 cm−3). We found that the ratio of 12CO(J = 3–2) to 12CO(J = 1–0) emission is sensitive to and is well correlated with the local Hα flux. We infer that differences of clump properties represent an evolutionary sequence of GMCs in terms of density increase leading to star formation. Type I and II GMCs (starless GMCs and GMCs with H II regions only, respectively) are at the young phase of star formation where density does not yet become high enough to show active star formation, and Type III GMCs (GMCs with H II regions and young star clusters) represent the later phase where the average density is increased and the GMCs are forming massive stars. The high kinetic temperature correlated with Hα flux suggests that FUV heating is dominant in the molecular gas of the LMC.

Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined from J = 3-2 and J = 1-0 Transitions of CO

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