Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene (c-C9H8) with GOTHAM Observations of TMC-1
Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene (c-C9H8) with GOTHAM Observations of TMC-1
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DOI：
10.3847/2041-8213/abfd3a
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发表时间：
2021-06-01
影响因子：
7.9
通讯作者：
McGuire, Brett A.
中科院分区：
文献类型：
--
作者：
Burkhardt, Andrew M.;Long Kelvin Lee, Kin;McGuire, Brett A.
多环芳烃(PAHs)长期以来一直被用于星际和原星际来源的研究，但直到最近才被证明难以明确识别任何单个的PAH。因此，这类重要分子的形成机制仍然没有得到很好的约束。在这里，我们报告了作为TMC-1的GBT观测的一部分：寻找芳香族分子(Gotham)调查的第一次星际探测到的纯烃多环芳烃--吲烯(C9H8)。这种检测为化学研究提供了一条新的途径，补充了现有的CN功能化芳香族分子的检测。从哥谭市的观测结果来看，吲哚被发现是迄今为止在TMC-1中检测到的最丰富的有机环。而用鹦鹉螺进行天体化学模拟，观测到的丰度比模型预测的丰度大几个数量级，这表明天体化学模型中的电流形成路径是不完整的。检测到相对较高丰度的吲哚意味着在黑暗的云层中可能可以检测到相关物种，如氰基吲烯、环戊二烯、甲苯和苯乙烯。
Polycyclic aromatic hydrocarbons (PAHs) have long been invoked in the study of interstellar and protostellar sources, but the unambiguous identification of any individual PAH has proven elusive until very recently. As a result, the formation mechanisms for this important class of molecules remain poorly constrained. Here we report the first interstellar detection of a pure hydrocarbon PAH, indene (C9H8), as part of the GBT Observations of TMC-1: Hunting for Aromatic Molecules (GOTHAM) survey. This detection provides a new avenue for chemical inquiry, complementing the existing detections of CN-functionalized aromatic molecules. From fitting the GOTHAM observations, indene is found to be the most abundant organic ring detected in TMC-1 to date. And from astrochemical modeling with nautilus, the observed abundance is greater than the model's prediction by several orders of magnitude, suggesting that current formation pathways in astrochemical models are incomplete. The detection of indene in relatively high abundance implies related species such as cyanoindene, cyclopentadiene, toluene, and styrene may be detectable in dark clouds.