ON THE UBIQUITY OF MOLECULAR ANIONS IN THE DENSE INTERSTELLAR MEDIUM
ON THE UBIQUITY OF MOLECULAR ANIONS IN THE DENSE INTERSTELLAR MEDIUM
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关于稠密星际介质中分子阴离子的普遍性
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
S. Charnley
中科院分区：
文献类型：
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作者：
M. Cordiner;M. Cordiner;J. Buckle;E. Wirström;E. Wirström;A. Olofsson;S. Charnley
结果是从分子阴离子在7个附近的银河系恒星形成的核心和分子云的调查。在所有七个目标源中检测到碳氢化合物阴离子C6 H −，包括四个以前没有检测到阴离子的源：L1172，L1389，L1495 B和TMC-1C。每个源的C6 H −/C6 H柱密度比为1.0%，平均值为3.0%（标准差为0.92%）。结合以前的检测，我们的研究结果表明，阴离子是无处不在的稠密的云C6 H存在。C6 H −/C6 H比率与分子氢数密度和云的表观年龄呈正相关。我们还报告了TMC-1中首次检测到C4 H −（置信度为4.8σ），并推导出阴离子与中性离子的比率C4 H −/C4 H =（1.2 ± 0.4）× 10−5（= 0.0012% ± 0.0004%）。与C6 H −相比，如此低的值突出了对C4 H的修订辐射电子附着率的需要。化学模型计算表明，观察到的C4 H −可能是氧原子与C5 H −和C6 H −反应的结果。
Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H− is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B, and TMC-1C. The C6H−/C6H column density ratio is ≳ 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C6H is present. The C6H−/C6H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C4H− in TMC-1 (at 4.8σ confidence), and derive an anion-to-neutral ratio C4H−/C4H =(1.2 ± 0.4) × 10−5(= 0.0012% ± 0.0004%). Such a low value compared with C6H− highlights the need for a revised radiative electron attachment rate for C4H. Chemical model calculations show that the observed C4H− could be produced as a result of reactions of oxygen atoms with C5H− and C6H−.
DOI：
10.1088/0067-0049/188/1/139
发表时间：
2010-04
期刊：
The Astrophysical Journal Supplement Series
影响因子：
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作者：
R. Launhardt;D. Nutter;D. Ward-Thompson;T. Bourke;T. Henning;T. Khanzadyan;T. Khanzadyan;M. Schmalzl;S. Wolf;S. Wolf;R. Zylka
通讯作者：
R. Launhardt;D. Nutter;D. Ward-Thompson;T. Bourke;T. Henning;T. Khanzadyan;T. Khanzadyan;M. Schmalzl;S. Wolf;S. Wolf;R. Zylka