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arXiv 1909.07590astro-ph.GAastro-ph.SR
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基于MWISP CO巡天和盖亚DR2的分子云距离

Molecular cloud distances based on the MWISP CO survey and Gaia DR2

Qing-Zeng Yan, Ji Yang, Yan Sun, Yang Su, Ye Xu

摘要:

我们提出了一种新的方法来计算分子云在银河系平面的距离,使用CO观测和盖亚DR 2视差和G-波段消光($A_G$)测量。由于银河平面尘埃环境的复杂性,$A_G$包含不规则的变化,这是很难建模。为了克服这个困难,我们建议,离云恒星(分子云周围的盖亚恒星)的$A_G$可以作为一个基线来校准云上恒星(朝向分子云的盖亚恒星)的$A_G$,这将去除与分子云无关的$A_G$成分。随后利用贝叶斯分析和马尔可夫链蒙特卡罗(MCMC)采样从云上$A_G$中的跳跃点推断距离。我们将这种基线减法应用于100平方度的区域(209.75° $\leq$ 1 $\leq$ 219.75°和|b| $\leq$ 5°),位于银河系第三象限,作为银河系成像卷轴画(MWISP)项目的一部分绘制,覆盖了三条CO同位素线,并推导出11个分子云的距离和质量,包括马达莱纳分子云和Sh 2-287结果表明,英仙座臂在该区域的距离约为2.4kpc,臂间区域存在分子云。

英文摘要:

We present a new method of calculating distances of molecular clouds in the Galactic plane, using CO observations and the Gaia DR2 parallax and G-band extinction ($A_G$) measurements. Due to the complexity of dust environments in the Galactic plane, $A_G$ contains irregular variations, which is difficult to model. To overcome this difficulty, we propose that the $A_G$ of off-cloud stars (Gaia stars around molecular clouds) can be used as a baseline to calibrate the $A_G$ of on-cloud stars (Gaia stars toward molecular clouds), which removes the $A_G$ components that are unrelated to molecular clouds. The distance is subsequently inferred from the jump point in on-cloud $A_G$ with Bayesian analysis and Markov chain Monte Carlo (MCMC) sampling. We applied this baseline subtraction method to a 100 square degree region (209.75° $\leq$ l $\leq$ 219.75° and |b| $\leq$ 5°) in the third Galactic quadrant, which was mapped as part of the Milky Way Imaging Scroll Painting (MWISP) project, covering three CO isotopologue lines, and derived distances and masses for 11 molecular clouds, including the Maddalena molecular cloud and Sh 2-287. The results indicate that the distance of the Perseus Arm in this region is about 2.4 kpc and molecular clouds are present in the interarm regions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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