DISCOVERY OF INTERSTELLAR ANIONS IN CEPHEUS AND AURIGA
DISCOVERY OF INTERSTELLAR ANIONS IN CEPHEUS AND AURIGA
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DOI：
10.1088/2041-8205/730/2/l18
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
M. Cordiner;S. Charnley;J. Buckle;C. Walsh;T. Millar
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作者：
M. Cordiner;S. Charnley;J. Buckle;C. Walsh;T. Millar
我们报告了在恒星形成区 L1251A（仙王座）和前恒星核心 L1512（御夫座）中碳氢化合物阴离子 C6H− 及其母体中性 C6H 的微波发射线的检测。还检测到大量丰度的碳链物种 C4H、HC3N、HC5N、HC7N 和 C3S。 L1251A 的观测构成了在仙王座耀斑恒星形成区域首次检测到阴离子、长链多炔和氰基多炔（具有超过 5 个碳原子），以及在金牛座分子云复合体之外的原恒星附近首次检测到阴离子，表明阴离子在恒星形成化学中可能具有更广泛的重要性。旋转激发温度源自 HC3N 超精细结构线，发现 L1251A 为 6.2 K，L1512 为 8.7 K。阴离子与中性比分别为3.6%和4.1%，这在先前在星际介质中观察到的值范围内，表明不同致密星际云中控制阴离子丰度的过程具有相对均匀性。这项研究提供了越来越多的证据，证明碳链阴离子在整个银河系的星际云中相对丰富，尤其是在前恒星核心和年轻的嵌入原恒星周围密度相对较高和高损耗的区域。
We report the detection of microwave emission lines from the hydrocarbon anion C6H− and its parent neutral C6H in the star-forming region L1251A (in Cepheus), and the pre-stellar core L1512 (in Auriga). The carbon-chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for L1512. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.