Detection and modelling of CH3NC in TMC-1
Detection and modelling of CH3NC in TMC-1
复制标题
TMC-1 中 CH3NC 的检测和建模
DOI：
10.1093/mnras/stad2398
复制
发表时间：
2023
影响因子：
4.8
通讯作者：
Herbst, Eric
中科院分区：
文献类型：
--
作者：
Tennis, Jessica D.;Xue, Ci;Talbi, Dahbia;Changala, P. Bryan;Sita, Madelyn L.;McGuire, Brett;Herbst, Eric
两个密切相关的异构对氰化物，CH 3 [CN/NC]和H2 C [CN/NC]，研究在寒冷，黑暗的星际云条件。与在太空中探测到的不同的甲基氰化物（CH 3CN）相比，甲基异氰化物（CH 3 NC）以前只在温暖和炎热的恒星形成区域被观察到。本文报道了用绿色堤望远镜在冷的星前核金牛座分子云（TMC-1）中探测到CH 3 NC，探测显著性为13.4σ。H2 CCN的超精细跃迁和CH 3CN和CH 3 NC的四极相互作用与TMC-1的绿色银行望远镜观测的光谱线相匹配：在绿色银行望远镜上寻找芳香分子大型项目，导致氢的丰度为氰基甲基自由基（H2 CCN），CH 3CN和CH 3 NC。在TMC-1条件下，用三相气粒codenautilusin模拟这些分子的努力过度产生了CH 3CN和CH 3 NC，尽管这些物种的观测和模型之间的比率为1.59%。这可能指向模型中缺失的销毁路线。该模型很好地捕捉了H2 CCN的较大丰度。解离重组被认为是这些分子的主要生产途径，并与丰富的离子反应被认为是主要的破坏途径。H + CH 3 NC的研究与过渡态理论作为一个潜在的破坏途径，但发现太慢，在冷云条件下，占模拟和观察到的丰度的CH 3 NC的差异。
Two closely related isomeric pairs of cyanides, CH3[CN/NC] and H2C[CN/NC], are studied in cold, dark interstellar cloud conditions. In contrast to the diverse detections of methyl cyanide (CH3CN) in space, methyl isocyanide (CH3NC) has previously only been observed in warm and hot star-forming regions. We report the detection of CH3NC in the cold pre-stellar core Taurus Molecular Cloud (TMC-1) using the Green Bank Telescope with a detection significance of 13.4σ. Hyperfine transitions in H2CCN and quadrupole interactions in CH3CN and CH3NC were matched to a spectral line survey from the Green Bank Telescope Observations of TMC-1: Hunting for Aromatic Molecules large project on the Green Bank Telescope, resulting in abundances with respect to hydrogen offor the cyanomethyl radical (H2CCN),for CH3CN, andfor CH3NC. Efforts to model these molecules with the three-phase gas-grain codenautilusin TMC-1 conditions overproduce both CH3CN and CH3NC, though the ratio of ∼5.9 per cent is consistent across observations and models of these species. This may point to missing destruction routes in the model. The models capture the larger abundance of H2CCN well. Dissociative recombination is found to be the primary production route for these molecules, and reactions with abundant ions are found to be the primary destruction routes. H + CH3NC is investigated with transition state theory as a potential destruction route, but found to be too slow in cold cloud conditions to account for the discrepancy in modelled and observed abundances of CH3NC.