Large scale IRAM 30 m CO-observations in the giant molecular cloud complex W43
Large scale IRAM 30 m CO-observations in the giant molecular cloud complex W43
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DOI：
10.1051/0004-6361/201321592
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发表时间：
2013-08
影响因子：
6.5
通讯作者：
P. Carlhoff;Q. N. Luong;P. Schilke;F. Motte;N. Schneider;H. Beuther;S. Bontemps;F. Heitsch;T. Hill;C. Kramer;V. Ossenkopf;F. Schuller;R. Simon;F. Wyrowski
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文献类型：
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作者：
P. Carlhoff;Q. N. Luong;P. Schilke;F. Motte;N. Schneider;H. Beuther;S. Bontemps;F. Heitsch;T. Hill;C. Kramer;V. Ossenkopf;F. Schuller;R. Simon;F. Wyrowski
我们的目标是全面描述巨型分子云复合体W43中致密分子云的分布和位置。此前，它被认为是银河系中质量最大的恒星形成区之一。为了追踪W43区中等密度的分子云，我们启动了一个名为W43-HERO的IRAM 30M大型程序，覆盖了大尺度的动态范围(从0.3到140 pC)。我们获得了~(13)CO(2-1)和~(18)O(2-1)的飞行图谱，光谱分辨率为0.1公里/S，空间分辨率为12“。这些地图覆盖了约1.5平方度的区域，包括了W43的两个主要云层，以及它们周围密度较低的气体。与银河系模型和以前的距离计算的比较证实了W43的位置靠近飞毛腿的切点，距离太阳大约6kpc。得到的观测区域的强度立方体被分成以单一云为中心的子立方体，然后进行详细分析。由~(13)CO和~(18)O数据得到了光学厚度、激发温度和H_2柱密度图。然后将这些结果与赫歇尔尘埃图的结果进行了比较。一个典型的云的质量是几个10^4太阳质量，而W43中致密分子气体(>；100 cm^-3)的总质量约为1.9个太阳质量。从分子线数据和赫歇尔成像得到的柱密度图得到的概率分布函数在低柱密度时呈对数正态分布，在高密度时呈幂函数分布。分子谱线数据PDF的斜率更平坦可能意味着，这些数据选择性地显示了引力坍塌的气体。
We aim to give a full description of the distribution and location of dense molecular clouds in the giant molecular cloud complex W43. It has previously been identified as one of the most massive star-forming regions in our Galaxy. To trace the moderately dense molecular clouds in the W43 region, we initiated an IRAM 30m large program, named W43-HERO, covering a large dynamic range of scales (from 0.3 to 140 pc). We obtained on-the-fly-maps in 13CO (2-1) and C18O (2-1) with a high spectral resolution of 0.1 km/s and a spatial resolution of 12". These maps cover an area of ~1.5 square degrees and include the two main clouds of W43, as well as the lower density gas surrounding them. A comparison with Galactic models and previous distance calculations confirms the location of W43 near the tangential point of the Scutum arm at a distance from the Sun of approximately 6 kpc. The resulting intensity cubes of the observed region are separated into sub-cubes, centered on single clouds which are then analyzed in detail. The optical depth, excitation temperature, and H2 column density maps are derived out of the 13CO and C18O data. These results are then compared with those derived from Herschel dust maps. The mass of a typical cloud is several 10^4 solar masses while the total mass in the dense molecular gas (>100 cm^-3) in W43 is found to be about 1.9e6 solar masses. Probability distribution functions obtained from column density maps derived from molecular line data and Herschel imaging show a log-normal distribution for low column densities and a power-law tail for high densities. A flatter slope for the molecular line data PDF may imply that those selectively show the gravitationally collapsing gas.