论文标题
鸟类以银河系的眼光视图：ii。从子PC到KPC量表的云运动学
Bird's eye view of molecular clouds in the Milky Way: II. Cloud kinematics from sub-pc to kpc scales
论文作者
论文摘要
分子气体的运动学对于为恒星形成奠定基础至关重要。与气体运动学特性有关的一个关键问题是它们如何依赖于空间尺度。我们旨在描述CO光谱，速度分散体，尤其是线宽大小的关系，从云（PARSEC-）尺度到分子磁盘内的整个区域中的分子气体（PARSEC-）尺度到千乘量表。我们从早期工作中利用了2 kpc的分子云的普查以及文献中的CO排放数据。我们研究了各个云样本的运动学和拉尔森的关系。我们还模仿了银河系的面向视图，并分析了孔径0.25-2 kpc的云层的运动学。通过这种方式，我们描述了CO气体运动学和拉尔森关系的规模依赖性。我们在调查区域中描述了CO气体在云量表和0.25-2 kpc之间的光谱中的光谱。光圈内的光谱相对对称，但显示非高斯高速机翼。在云规模上，我们的样本显示了线宽大小的关系σ_v= 1.5*r^{0.3 \ pm0.1}，具有较大的散布。云样本中的质量大小关系为m_ {co} = 794*r^{1.5 \ pm0.5}。对于KPC尺度的孔径也存在关系。可以看到对银河环境的暗示性依赖性，孔更靠近银河中心和具有较高速度分散体的射手座螺旋臂。我们探讨了调查区域中弥漫组件的可能影响，并发现这种组件会扩大CO光谱，并可以使线宽大小的关系变平。了解可能的弥漫性CO成分的性质及其对观测的影响对于连接银河系和外层面数据至关重要。
The kinematics of molecular gas are crucial for setting the stage for star formation. One key question related to the kinematic properties of gas is how they depend on the spatial scale. We aim to describe the CO spectra, velocity dispersions, and especially the linewidth-size relation, of molecular gas from cloud (parsec-) scales to kiloparsec scales in a complete region within the Milky Way disk. We utilise the census of molecular clouds within 2 kpc from our earlier work, together with CO emission data for them from the literature. We study the kinematics and the Larson's relations for the sample of individual clouds. We also mimic a face-on view of the Milky Way and analyse the kinematics of the clouds within apertures of 0.25-2 kpc in size. In this way, we describe the scale-dependency of the CO gas kinematics and Larson's relations. We describe the spectra of CO gas at cloud scales and in apertures between 0.25-2 kpc in our survey area. The spectra within the apertures are relatively symmetric but show non-Gaussian high-velocity wings. At cloud-scales, our sample shows a linewidth-size relation σ_v=1.5*R^{0.3\pm0.1} with a large scatter. The mass-size relation in the sample of clouds is M_{CO}= 794*R^{1.5\pm0.5}. The relations are also present for the apertures at kpc-scales. A suggestive dependency on galactic environment is seen, with apertures closer to the Galactic centre and the Sagittarius spiral arm having slightly higher velocity dispersions. We explore the possible effect of a diffuse component in the survey area, and find that such a component would widen the CO spectra and could flatten the linewidth-size relation. Understanding the nature of the possible diffuse CO component and its effects on observations is crucial for connecting Galactic and extragalactic data.
