We report an astronomical detection of HC 4 NC for the first time in the interstellar medium with the Green Bank Telescope toward the TMC-1 molecular cloud with a minimum significance of 10.5 σ . The total column density and excitation temperature of HC 4 NC are determined to be ##IMG## [http://ej.iop.org/images/2041-8205/900/1/L9/apjlaba631ieqn1.gif] {${3.29}_{-1.20}^{+8.60}\times {10}^{11}$} cm −2 and ##IMG## [http://ej.iop.org/images/2041-8205/900/1/L9/apjlaba631ieqn2.gif] {${6.7}_{-0.3}^{+0.3}\ {\rm{K}}$} , respectively, using Markov chain Monte Carlo analysis. In addition to HC 4 NC, HCCNC is distinctly detected whereas no clear detection of HC 6 NC is made. We propose that the dissociative recombination of the protonated cyanopolyyne, HC 5 NH + , and the protonated isocyanopolyyne, HC 4 NCH + , are the main formation mechanisms for HC 4

中文翻译：

---

TMC-1条件下星际HC 4 NC的检测和异氰基聚炔化学的研究

我们报道了首次使用Green Bank望远镜向星际介质中的HC 4 NC进行天文探测，其方向为TMC-1分子云，最低显着性为10.5σ。HC 4 NC的总柱密度和激发温度确定为## IMG ## [http://ej.iop.org/images/2041-8205/900/1/L9/apjlaba631ieqn1.gif] {$ { 3.29} _ {-1.20} ^ {+ 8.60} \倍{10} ^ {11} $} cm −2和## IMG ## [http://ej.iop.org/images/2041-8205/900分别使用Markov链蒙特卡洛分析（/1/L9/apjlaba631ieqn2.gif）{$ {6.7} _ {-0.3} ^ {+ 0.3} \ {\ rm {K}} $}。除了HC 4 NC之外，还明显检测到HCCNC，而没有明确检测HC 6 NC。我们建议质子化的氰基多炔HC 5 NH +和质子化的异氰基多炔HC 4 NCH +的解离重组是HC 4的主要形成机理。