Discovery of CH<sub>2</sub>CHCCH and detection of HCCN, HC<sub>4</sub>N, CH<sub>3</sub>CH<sub>2</sub>CN, and, tentatively, CH<sub>3</sub>CH<sub>2</sub>CCH in TMC-1
J. Cernicharo, M. Agúndez, C. Cabezas, N. Marcelino, B. Tercero, J. R. Pardo, J. D. Gallego, F. Tercero, J. A. López-Pérez, P. de Vicente
Abstract
We present the discovery in TMC-1 of vinyl acetylene, CH 2 CHCCH, and the detection, for the first time in a cold dark cloud, of HCCN, HC 4 N, and CH 3 CH 2 CN. A tentative detection of CH 3 CH 2 CCH is also reported. The column density of vinyl acetylene is (1.2 ± 0.2) × 10 13 cm −2 , which makes it one of the most abundant closed-shell hydrocarbons detected in TMC-1. Its abundance is only three times lower than that of propylene, CH 3 CHCH 2 . The column densities derived for HCCN and HC 4 N are (4.4 ± 04) × 10 11 cm −2 and (3.7 ± 0.4) × 10 11 cm −2 , respectively. Hence, the HCCN/HC 4 N abundance ratio is 1.2 ± 0.3. For ethyl cyanide we derive a column density of (1.1 ± 0.3) × 10 11 cm −2 . These results are compared with a state-of-the-art chemical model of TMC-1, which is able to account for the observed abundances of these molecules through gas-phase chemical routes.