Combination of CN(1-0), HCN(1-0), and HNC(1-0): A possible indicator for a high-mass star formation sequence in the Milky Way
Combination of CN(1-0), HCN(1-0), and HNC(1-0): A possible indicator for a high-mass star formation sequence in the Milky Way
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CN(1-0)、HCN(1-0) 和 HNC(1-0) 的组合：银河系中高质量恒星形成序列的可能指标
DOI：
10.1051/0004-6361/201423791
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发表时间：
2015
影响因子：
6.5
通讯作者：
Na Wang
中科院分区：
文献类型：
--
作者：
Xiaohong Han;Jianjun Zhou;Junzhi Wang;Jarken Esimbek;JIangshui Zhang;Na Wang
CN，HCN，HNC等谱线已被用来讨论星系中的星星形成序列，但最近对涉及这些谱线的大样本的研究还没有提供令人信服的结果。目的我们打算确定CN/HCN，CN/HNC，HCN/HNC等谱线比值是否可以用来追踪银河系中的高质量星星形成序列。方法我们对CN（1-0），HCN（1-0），HNC（1-0）和HNC（1-0）分别指向38个大质量恒星形成区，包括大质量无星核（HMSC）、大质量原恒星（HMPO）、UCHII（超致密HII）和正常HII区。我们确定了与它们相关的分子团簇，并去除了受环境影响的分子团簇。我们平均所有检测到的发射从每个集群，以获得全球线比，并调查其变化与高质量的恒星形成clusters.ResultsThe全球线比ICN/IHNCandIHCN/IHNC的HMSC集群（HMSCCs），HMPO集群（HMPOCs），UCHII区域集群（UCHIICs），和HII区域集群的演化阶段显示出增加的趋势。我们尝试性地将恒星形成区分为两种类型。第1类源包括HMSCC和HMPOCs，它们与外部20 cm连续辐射无关。第2类来源包括所有UCHIIC和HIIC。我们的分析表明，ICN/IHN和IHCN/IHNC系比值可以很好地跟踪从1型到2型的演变。结论ICN/IHN和IHCN/IHNC是研究银河系高质量恒星形成区演化的良好示踪剂。
ContextCN, HCN, and HNC have been used to discuss the star formation sequence in galaxies, but recent studies of large samples involving these lines did not yet provide convincing results.AimsWe intend to determine whether the global line ratios CN/HCN, CN/HNC, and HCN/HNC can be used to trace the high-mass star formation sequence in the Milky Way.MethodsWe performed map observations of CN(1-0), HCN(1-0), and HNC(1-0) toward 38 high-mass star-forming regions, which includes high-mass starless cores (HMSC), high-mass protostars (HMPO), UCHII (ultra-compact HII) and normal HII regions. We identified the molecular clumps associated with them, and removed the clumps that were affected by environment. We averaged all the detected emission from each clump to obtain global line ratios and investigated their variations with the evolutionary stages of high-mass star-forming clumps.ResultsThe global line ratios ofICN/IHNCandIHCN/IHNCfor HMSC clumps (HMSCCs), HMPO clumps (HMPOCs), UCHII region clumps (UCHIICs), and HII region clumps display an increasing trend. We tentatively divide the star-forming regions into two types. Type 1 sources include HMSCCs and HMPOCs that are not associated with external 20 cm continuum emission. Type 2 sources include all UCHIICs and HIICs. Our analysis shows that theICN/IHNCandIHCN/IHNCline ratios can trace the evolution from type 1 to type 2 well. The same method may be used to study the evolution of external galaxies.ConclusionsICN/IHNCandIHCN/IHNCappear to be good tracers for the evolution of high-mass star-forming regions in the Milky Way.