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arXiv · 2501.01938

Identification of the interstellar 1-cyano propargyl radical (HCCCHCN) in TMC-1

C. Cabezas·M. Agúndez·N. Marcelino·C. H. Chang·R. Fuentetaja·B. Tercero·M. Nakajima·Y. Endo·P. de Vicente·J. Cernicharo
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Abstract

We report the first detection in interstellar medium of the 1-cyano propargyl radical, HC$_3$HCN. This species is an isomer of the 3-cyano propargyl radical (CH$_2$C$_3$N), which was recently discovered in TMC-1. The 1-cyano propargyl radical was observed in the cold dark cloud TMC-1 using data from the ongoing QUIJOTE line survey, which is being carried out with the Yebes 40m telescope. A total of seven rotational transitions with multiple hyperfine components were detected in the 31.0-50.4 GHz range. We derived a column density of (2.2$\pm$0.2)$\times$10$^{11}$ cm$^{-2}$ and a rotational temperature of 7$\pm$1\,K. The abundance ratio between HC$_3$HCN and CH$_2$C$_3$N is 1.4. The almost equal abundance of these isomers indicates that the two species may be produced in the same reaction with a similar efficiency, probably in the reaction C + CH$_2$CHCN and perhaps also in the reaction C$_2$ + CH$_3$CN and the dissociative recombination with electrons of CH$_2$C$_3$NH$^+$

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C. Cabezas, M. Agúndez, N. Marcelino, C. H. Chang, R. Fuentetaja, B. Tercero, M. Nakajima, Y. Endo, P. de Vicente, J. Cernicharo. 2025-01-03. Identification of the interstellar 1-cyano propargyl radical (HCCCHCN) in TMC-1. https://arxiv.org/abs/2501.01938

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