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arXiv 2102.12199astro-ph.GA
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Milky Way中平面第二象限中的分子云从l $=$ 104 $.\!\!^{\circ}$ 75到l=119 $.\!\!^{\circ}$ 75和b= $-$ 5 $.\!\!^{\circ}$ 25到b=5 $.\!\!^{\circ}$ 25

Molecular Clouds in the Second Quadrant of the Milky Way Mid-plane from l$=$104$.\!\!^{\circ}$75 to l=119$.\!\!^{\circ}$75 and b=$-$5$.\!\!^{\circ}$25 to b=5$.\!\!^{\circ}$25

Yuehui Ma, Hongchi Wang, Chong Li, Lianghao Lin, Yan Sun, Ji Yang

摘要:

我们研究了银河系中面第二象限1 $=$ 104 $.\!\!^{\circ}$ 75 ~ 1 $=$ 119 $.\!\!^{\circ}$ 75和b $=-$ 5 $.\!\!^{\circ}$ 25至b $=$ 5 $.\!\!^{\circ}$ $.\!\!^{\circ}$ 25使用$^{12}$ CO,$^{13}$ CO,和来自银河成像卷轴画项目(MWISP)的C $^{18}$ O $J=1-0$发射线数据。我们已经确定了857和300云的$^{12}$ CO和$^{13}$ CO光谱立方体,分别使用的DENDRONOTES + SCIMES算法。估算了分子云的距离,并将分子云的质量、大小和表面密度等物理性质制成表格。英仙座旋臂中的分子云比本星系旋臂中的分子云质量大50倍,体积大6倍。然而,这一结果可能受到距离选择效应的影响。云的表面密度在英仙座臂中增加,平均值为$\sim$ 100 M $_{\odot}$ pc $^{-2}$。我们从$^{12}$ CO星表中选择了40个最扩展的($>$ 0.35 arcdeg $^2$)分子云来构建H $_2$柱密度概率分布函数(N-PDF)。约有78%的分子云的N-PDF在高密度下与对数正态函数拟合良好,偏差很小,对应的恒星形成区的尺度在Local臂为$\sim$ 1-5 pc,在Perseus臂为$\sim$ 5-10 pc,约有18%的分子云在高密度下具有幂律N-PDF。在这些分子云中,大多数符合幂律的区域对应于$\sim$ 1 pc大小的分子团或$\sim$ 1 pc宽度的细丝。

英文摘要:

We have studied the properties of molecular clouds in the second quadrant of the Milky Way Mid-plane from l$=$104$.\!\!^{\circ}$75 to l$=$119$.\!\!^{\circ}$75 and b$=-$5$.\!\!^{\circ}$25 to b$=$5$.\!\!^{\circ}$25 using the $^{12}$CO, $^{13}$CO, and C$^{18}$O $J=1-0$ emission line data from the Milky Way Imaging Scroll Painting project (MWISP). We have identified 857 and 300 clouds in the $^{12}$CO and $^{13}$CO spectral cubes, respectively, using the DENDROGRAM + SCIMES algorithms. The distances of the molecular clouds are estimated and the physical properties like masses, sizes, 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 biased by distance selection effects. The surface densities of the clouds are enhanced in the Perseus arm with an average value of $\sim$100 M$_{\odot}$ pc$^{-2}$. We selected the 40 most extended ($>$0.35 arcdeg$^2$) molecular clouds from the $^{12}$CO catalog to build the H$_2$ column density probability distribution function (N-PDF). About 78\% of the N-PDFs of the selected molecular clouds are well fitted with log-normal functions with only small deviations at high-densities which correspond to star-forming regions with scales of $\sim$1-5 pc in the Local arm and $\sim$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 of sizes of $\sim$1 pc or filaments of widths of $\sim$1 pc.

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