论文标题
年轻高质量星形成团块的化学结构：（ii）$ \ rm hco^+$的Parsec-Scale co Co Depletion和氘级分。
The chemical structure of young high-mass star-forming clumps: (II) parsec-scale CO depletion and deuterium fraction of $\rm HCO^+$
论文作者
论文摘要
冷和致密分子云的物理和化学特性是了解恒星如何形成的关键。使用IRAM 30 m和NRO 45 M望远镜，我们对70美元的深色和明亮云（MIAO）进行了多波伦长的线模仿调查。在线性分辨率为0.1--0.5 PC的情况下，这项工作详细介绍了Parsec-Scale Co耗竭和$ \ rm HCO^+$ deuterium（D-）分数（d-）对四个来源（G11.38+0.81，G15.22-0.43，G15.22-0.43，G14.49-0.49-0.13，g34.74--0.11-12），我们的示例包括在内。在每个来源中，$ \ rm t <20 $ k和$ n _ {\ rm h} \ rm \ sim10^4 $ - $ \ rm 10^5 cm^{ - 3} $，我们比较了一对相邻的70 $ $ $ m $ m $ m的明亮和深色团块和$ \ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ rm h_2 $ （2）CO同位素线和密集的燃气示踪剂的空间分布，例如1--0行$ \ rm H^{13} co^+$和$ \ rm dco^+$，是反相关的； （3）$ \ rm c^{18} o $和$ \ rm dco^+$之间的丰度比显示与源温度有很强的相关性； （4）$ \ rm c^{18} o $ $ deptetion因子和$ \ rm hco^+$的d算法都显示出从年轻团块到更具进化的团块的强劲减少，均超过3倍以上; （5）初步化学建模表明我们来源的化学年龄为$ {\ sim} 8 \ times10^4 $ yr，这与它们的自由下落时间尺度相当，并且比其收缩时间尺度小，这表明我们的来源可能是动态和化学的。
The physical and chemical properties of cold and dense molecular clouds are key to understanding how stars form. Using the IRAM 30 m and NRO 45 m telescopes, we carried out a Multiwavelength line-Imaging survey of the 70 $μ$m dark and bright clOuds (MIAO). At a linear resolution of 0.1--0.5 pc, this work presents a detailed study of parsec-scale CO depletion and $\rm HCO^+$ deuterium (D-) fractionation toward four sources (G11.38+0.81, G15.22-0.43, G14.49-0.13, and G34.74-0.12) included in our full sample. In each source with $\rm T<20$ K and $n_{\rm H}\rm\sim10^4$--$\rm 10^5 cm^{-3}$, we compared pairs of neighboring 70 $μ$m bright and dark clumps and found that (1) the $\rm H_2$ column density and dust temperature of each source show strong spatial anticorrelation; (2) the spatial distribution of CO isotopologue lines and dense gas tracers, such as 1--0 lines of $\rm H^{13}CO^+$ and $\rm DCO^+$, are anticorrelated; (3) the abundance ratio between $\rm C^{18}O$ and $\rm DCO^+$ shows a strong correlation with the source temperature; (4) both the $\rm C^{18}O$ depletion factor and D-fraction of $\rm HCO^+$ show a robust decrease from younger clumps to more evolved clumps by a factor of more than 3; and (5) preliminary chemical modeling indicates chemical ages of our sources are ${\sim}8\times10^4$ yr, which is comparable to their free-fall timescales and smaller than their contraction timescales, indicating that our sources are likely dynamically and chemically young.
