论文标题
第一个银河象限中局部分子云的距离和统计数据
Distances and statistics of local molecular clouds in the first Galactic quadrant
论文作者
论文摘要
我们介绍了第一个银河象限（25.8°<l <49.7°和| b | <5°）中局部分子云（-6 <vlsr <30 km/s，即<1.5 kpc），这是银河系的试点卷卷绘画（MWISP）CO co couse。使用SCIMES算法将大分子云分为中等大小的云，我们确定了使用GAIA DR2差异测量的AG和AV的距离，具有背景 - 重生的灭绝 - Parallax方法（BEEP）方法（BEEP）方法，距离范围从250 PC到约1.5 kpc。这些不完整的距离样品表明距离和径向速度（VLSR）之间的线性关系，散射为0.16 kpc，对于局部分子云，运动距离可能会系统地较大。为了研究分子云的基本特性，例如总样本数，线宽，亮度温度，物理面积和质量，我们使用DBSCAN算法分解了光谱立方体。在DBSCAN簇上施加了后选择标准以消除噪声污染，我们发现分子云个体的分离是基于对L-B-V空间中独立连续结构的定义可靠的。 MWISP CO调查收集的局部分子云通量的完整性约为80％。物理区域A显示了幂律分布，DN/DA \ Propto a^{ - 2.20 +/- 0.18}，而分子云质量也遵循幂律分布但稍微平整，DN/DM \ propto m^{ - 1.96 +/- 0.11}。
We present an analysis of local molecular clouds (-6 <VLSR< 30 km/s, i.e., <1.5 kpc) in the first Galactic quadrant (25.8° <l<49.7° and |b|<5°), a pilot region of the Milky Way Imaging Scroll Painting (MWISP) CO survey. Using the SCIMES algorithm to divide large molecular clouds into moderate-sized ones, we determined distances to 28 molecular clouds with the background-eliminated extinction-parallax (BEEP) method using the Gaia DR2 parallax measurements aided by AG and AV, and the distance ranges from 250 pc to about 1.5 kpc. These incomplete distance samples indicate a linear relationship between the distance and the radial velocity (VLSR) with a scatter of 0.16 kpc, and kinematic distances may be systematically larger for local molecular clouds. In order to investigate fundamental properties of molecular clouds, such as the total sample number, the linewidth, the brightness temperature, the physical area, and the mass, we decompose the spectral cube using the DBSCAN algorithm. Post selection criteria are imposed on DBSCAN clusters to remove the noise contamination, and we found that the separation of molecular cloud individuals is reliable based on a definition of independent consecutive structures in l-b-V space. The completeness of the local molecular cloud flux collected by the MWISP CO survey is about 80%. The physical area, A, shows a power-law distribution, dN/dA \propto A^{-2.20+/-0.18}, while the molecular cloud mass also follows a power-law distribution but slightly flatter, dN/dM \propto M^{-1.96+/-0.11}.
