标题： 在TMC-1中发现乙炔基环戊二烯的两种异构体：碳氢环的CCH和CN衍生物的丰度 显示英文标题

标题： Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles

摘要： 我们报告在TMC-1方向检测到乙炔基环戊二烯（c-C5H5CCH）的两种异构体，即1-和2-乙炔基-1,3-环戊二烯。我们推导出这两种环戊二烯衍生物的柱密度分别为(1.4 +/- 0.2)e12 cm-2和(2.0 +/- 0.4)e12 cm-2，这表明它们的丰度大约是环戊二烯的十分之一。我们还报告了乙炔基苯（C6H5CCH）的初步检测，我们估计其柱密度为(2.5 +/- 0.4)e12 cm-2。我们推导出环戊二烯和苯相应的氰基衍生物的丰度，并发现这些值显著低于之前报道的数值。这些环的乙炔基和氰基衍生物的旋转温度约为9 K，非常接近云的气体动力学温度。乙炔基环戊二烯的1-和2-异构体的丰度比为1.4 +/- 0.5，而氰基环戊二烯的两种异构体的丰度比为2.4 +/- 0.6。环戊二烯中CCH相对于CN衍生物的相对丰度为7.7 +/- 2.2，这可能反映了自由基CCH和CN的丰度比；该比值在苯中仅为2.1 +/- 0.5，这表明除了氰基自由基与苯的反应外，还有其他反应参与了苯甲腈的形成。这些环的形成通过基于中性-中性反应的化学方案得到了合理的解释。预测在TMC-1中苯的丰度应与环戊二烯相当。 显示英文摘要

摘要： We report the detection of two isomers of ethynyl cyclopentadiene (c-C5H5CCH), namely 1- and 2-ethynyl-1,3-cyclopentadiene, in the direction of TMC-1. We derive column densities of (1.4 +/- 0.2)e12 cm-2, and (2.0 +/- 0.4)e12 cm-2, respectively, for these two cyclopentadiene derivatives, which imply that they are about ten times less abundant than cyclopentadiene. We also report the tentative detection of ethynyl benzene (C6H5CCH), for which we estimate a column density of (2.5 +/-0.4)e12 cm-2. We derived abundances for the corresponding cyano derivatives of cyclopentadiene and benzene and found values significantly lower than previously reported. The rotational temperature of the ethynyl and cyano derivatives of these cycles is about 9 K, that is, very close to the gas kinetic temperature of the cloud. The abundance ratio of the 1- and 2- isomers of ethynyl cyclopentadiene is 1.4 +/-0.5, while for the two isomers of cyano cyclopentadiene it is 2.4 +/- 0.6. The relative abundances of CCH over CN derivatives is 7.7 +/- 2.2 for cyclopentadiene, which probably reflects the abundance ratio of the radicals CCH and CN; this ratio is only 2.1 +/- 0.5 for benzene, which suggests that additional reactions besides cyano radicals with benzene are involved in the formation of benzonitrile. The formation of these cycles is reasonably well accounted for through a chemical scheme based on neutral-neutral reactions. It is predicted that benzene should be as abundant as cyclopentadiene in TMC-1.