Large-scale Spectroscopic Mapping of the ρ Ophiuchi Molecular Cloud Complex. I. The C2H-to-N2H+ Ratio as a Signpost of Cloud Characteristics
文献类型：期刊论文
| 作者 | Pan,Zhichen1; Li,Di1,3,6; Chang,Qiang4; Qian,Lei1,6; Bergin,Edwin A.5; Wang,Junzhi2 |
| 刊名 | The Astrophysical Journal
 |
| 出版日期 | 2017-02-21 |
| 卷号 | 836期号:2 |
| 关键词 | ISM: individual objects (ρ Ophiuchi molecular cloud complex) ISM: molecules radio lines: ISM stars: formation |
| ISSN号 | 0004-637X |
| DOI | 10.3847/1538-4357/aa5c33 |
| 英文摘要 | Abstract We present 2.5-square-degree C2H N?=?1–0 and N2H+ J?=?1–0 maps of the ρ Ophiuchi molecular cloud complex. These are the first large-scale maps of the ρ Ophiuchi molecular cloud complex with these two tracers. The C2H emission is spatially more extended than the N2H+ emission. One faint N2H+ clump, Oph-M, and one C2H ring, Oph-RingSW, are identified for the first time. The observed C2H-to-N2H+ abundance ratio ([C2H]/[N2H+]) varies between 5 and 110. We modeled the C2H and N2H+ abundances with 1D chemical models, which show a clear decline of [C2H]/[N2H+] with chemical age. Such an evolutionary trend is little affected by temperatures when they are below 40 K. At high density (nH?>?105 cm?3), however, the time it takes for the abundance ratio to drop at least one order of magnitude becomes less than the dynamical time (e.g., turbulence crossing time of ～105 yr). The observed [C2H]/[N2H+] difference between L1688 and L1689 can be explained by L1688 having chemically younger gas in relatively less dense regions. The observed [C2H]/[N2H+] values are the results of time evolution, accelerated at higher densities. For the relatively low density regions in L1688 where only C2H emission was detected, the gas should be chemically younger. |
| 语种 | 英语 |
| WOS记录号 | IOP:0004-637X-836-2-AA5C33 |
| 出版者 | The American Astronomical Society |
| 源URL | [http://119.78.226.72/handle/331011/32145]  |
| 专题 | 中国科学院上海天文台 |
| 作者单位 | 1.National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012, China; panzc@nao.cas.cn, dili@nao.cas.cn 2.Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China 3.University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing, China 4.Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi 830011, China 5.Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109, USA 6.Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, China |
| 推荐引用方式 GB/T 7714 | Pan,Zhichen,Li,Di,Chang,Qiang,et al. Large-scale Spectroscopic Mapping of the ρ Ophiuchi Molecular Cloud Complex. I. The C2H-to-N2H+ Ratio as a Signpost of Cloud Characteristics[J]. The Astrophysical Journal,2017,836(2). |
| APA | Pan,Zhichen,Li,Di,Chang,Qiang,Qian,Lei,Bergin,Edwin A.,&Wang,Junzhi.(2017).Large-scale Spectroscopic Mapping of the ρ Ophiuchi Molecular Cloud Complex. I. The C2H-to-N2H+ Ratio as a Signpost of Cloud Characteristics.The Astrophysical Journal,836(2). |
| MLA | Pan,Zhichen,et al."Large-scale Spectroscopic Mapping of the ρ Ophiuchi Molecular Cloud Complex. I. The C2H-to-N2H+ Ratio as a Signpost of Cloud Characteristics".The Astrophysical Journal 836.2(2017). |
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