Issue |
A&A
Volume 687, July 2024
|
|
---|---|---|
Article Number | L22 | |
Number of page(s) | 5 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202451081 | |
Published online | 30 July 2024 |
Letter to the Editor
Discovery of the interstellar cyanoacetylene radical cation HC3N+ ⋆
1
Dept. de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
e-mail: carlos.cabezas@csic.es; jose.cernicharo@csic.es
2
Department of Applied Chemistry, Science Building II, National Yang Ming Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 300098, Taiwan
3
Observatorio Astronómico Nacional (OAN, IGN), C/ Alfonso XII, 3, 28014 Madrid, Spain
4
Observatorio de Yebes (IGN), Cerro de la Palera s/n, 19141 Yebes, Guadalajara, Spain
Received:
12
June
2024
Accepted:
28
June
2024
We report the first identification in space of HC3N+, the simplest member of the family of cyanopolyyne cations. Three rotational transitions with half-integer quantum numbers from J = 7/2 to 11/2 have been observed with the Yebes 40 m radio telescope and assigned to HC3N+, which has an inverted 2Π ground electronic state. The three rotational transitions exhibit several hyperfine components due to the magnetic and nuclear quadrupole coupling effects of the H and N nuclei. We confidently assign the characteristic rotational spectrum pattern to HC3N+ based on the good agreement between the astronomical and theoretical spectroscopic parameters. We derived a column density of (6.0 ± 0.6)×1010 cm−2 and a rotational temperature of 4.5 ± 1 K. The abundance ratio between HC3N and HC3N+ is 3200 ± 320. As found for the larger members of the family of cyanopolyyne cations (HC5N+ and HC7N+), HC3N+ is mainly formed through the reactions of H2 and the cation C3N+ and by the reactions of H+ with HC3N. In the same manner than other cyanopolyyne cations, HC3N+ is mostly destroyed through a reaction with H2 and a dissociative recombination with electrons.
Key words: astrochemistry / line: identification / molecular data / ISM: molecules / ISM: individual objects: TMC-1
© The Authors 2024
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