The Astrophysical Journal Supplement Series ( IF 8.7 ) Pub Date : 2021-04-19 , DOI: 10.3847/1538-4365/abe85c Yuehui Ma 1, 2 , Hongchi Wang 1, 3 , Chong Li 1, 2 , Lianghao Lin 1, 3 , Yan Sun 1 , Ji Yang 1
In this work, we study the properties of molecular clouds in the second quadrant of the Milky Way Midplane, from l = 104.75 to l = 119.75, and b = −5.25 to b = 5.25, using the 12CO, 13CO, and C18O J = 1 − 0 emission line data from the Milky Way Imaging Scroll Painting project. We identify 857 and 300 clouds in the 12CO and 13CO spectral cubes, respectively, using the DENDROGRAM + SCIMES algorithms. The distances of the molecular clouds are estimated, and physical properties such as the mass, size, and surface densities of the clouds are tabulated. The molecular clouds in the Perseus Arm are about 30−50 times more massive, and 4−6 times larger than the clouds in the Local Arm. This result, however, is likely to be biased by distance selection effects. The surface densities of the clouds are enhanced in the Perseus Arm, with an average value of ∼100 M ⊙ pc−2. Here. we select the 40 most extended (>0.35 arcdeg2) molecular clouds from the 12CO catalog to build the H2 column density probability distribution function (N-PDF). Some 78% of the N-PDFs of the selected molecular clouds are well fitted with log-normal functions with only small deviations at high densities, corresponding to star-forming regions with scales of ∼1–5 pc in the Local Arm, and ∼5–10 pc in the Perseus Arm. About 18% of the selected molecular clouds have power-law N-PDFs at high densities. In these molecular clouds, the majority of the regions fitted with the power law correspond to molecular clumps at sizes of ∼1 pc, or filaments at widths of ∼1 pc.
中文翻译:
银河系中平面第二象限中的分子云,从 l = 104.75 到 l = 119.75 和 b = -5.25 到 b = 5.25
在这项工作中,我们使用12 CO、13 CO 和 C研究了银河系中平面第二象限中分子云的特性,从l = 104.75 到l = 119.75,以及b = -5.25 到b = 5.25 18 O J = 1 − 0 来自银河成像滚动绘画项目的发射线数据。我们在12 CO 和13CO 光谱立方体,分别使用 DENDROGRAM + SCIMES 算法。估计分子云的距离,并列出云的质量、大小和表面密度等物理特性。Perseus Arm 中的分子云比 Local Arm 中的分子云质量大 30-50 倍,大 4-6 倍。然而,这个结果可能会受到距离选择效应的影响。英仙臂云的表面密度增加,平均值为~100 M ⊙ pc -2。这里。我们从12 CO 目录中选择 40 个最扩展(>0.35 arcdeg 2)的分子云来构建 H 2列密度概率分布函数 (N-PDF)。所选分子云的大约 78% 的 N-PDF 很好地拟合了对数正态函数,在高密度下只有很小的偏差,对应于局部臂中尺度为~1-5 pc 的恒星形成区域,并且~ Perseus Arm 中 5–10 件。大约 18% 的选定分子云具有高密度的幂律 N-PDF。在这些分子云中,符合幂律的大部分区域对应于约 1 pc 大小的分子团块,或约 1 pc 宽度的细丝。