We report the discovery of two unsaturated organic species, trans-(E)-cyanovinylacetylene and vinylcyanoacetylene, using the second data release of the GOTHAM deep survey toward TMC-1 with the 100 m Green Bank Telescope. For both detections, we performed velocity stacking and matched filter analyses using Markov Chain Monte Carlo simulations, and for trans-(E)-cyanovinylacetylene, three rotational lines were observed at low signal-to-noise (∼3σ). From this analysis, we derive column densities of 2 10¹¹ and 3 10¹¹ cm⁻² for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of <2 10¹¹ cm⁻² for trans-(Z)-cyanovinylacetylene. Comparisons with G3//B3LYP semiempirical thermochemical calculations indicate abundances of the [H₃C₅N] isomers are not consistent with their thermodynamic stability, and instead their abundances are mainly driven by dynamics. We provide a discussion on how these species may be formed in TMC-1, with reference to related molecules like vinyl cyanide (CH₂ = CHC ≡ N). As part of this discussion, we performed the same analysis for ethyl cyanide (CH₃CH₂C ≡ N), the hydrogenation product of CH₂ = CHC ≡ N. This analysis provides evidence—at 4.2σ significance—of an upper limit to the column density of <4 10¹¹ cm⁻²; an order of magnitude lower than previous upper limits toward this source.

我们报告了使用100 m Green Bank望远镜对TMC-1进行的GOTHAM深层调查的第二个数据发布，发现了两个不饱和有机物，即反式-（E）-氰基乙烯基乙炔和乙烯基氰基乙炔。对于这两种检测中，我们执行速度堆叠和匹配滤波器分析使用马尔可夫链Monte Carlo模拟，以及用于反式- （E）-cyanovinylacetylene，分别在低信号-噪声（〜3观察到三个旋转线σ）。通过该分析，我们得出乙烯基氰基乙炔和反式-（E）-氰基乙烯基乙炔的柱密度分别为2 10 ¹¹和3 10 ¹¹ cm ^-2，上限<2 10 ¹¹ cm对于反式-（Z）-氰基乙烯基乙炔为^-2。与G3 // B3LYP半经验热化学计算的比较表明，[H ₃ C ₅ N]异构体的丰度与其热力学稳定性不一致，相反，其丰度主要由动力学驱动。我们将参考相关的分子，如乙烯基氰（CH ₂ = CHC≡N），讨论如何在TMC-1中形成这些物质。作为该讨论的一部分，我们为乙基氰化物（CH进行同样的分析₃ CH ₂ C ^≡N），CH的氢化产物₂ = CHC≡N.此分析提供的证据，在4 2σ显着性-小于4 10 ¹¹ cm ^-2的色谱柱密度的上限；比此来源的先前上限低一个数量级。