Volume 650, June 2021
|Number of page(s)||5|
|Section||Letters to the Editor|
|Published online||15 June 2021|
Letter to the Editor
Cumulene carbenes in TMC-1: Astronomical discovery of l-H2C5⋆
Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
e-mail: email@example.com, firstname.lastname@example.org
2 Observatorio Astronómico Nacional (IGN), C/ Alfonso XII, 3, 28014 Madrid, Spain
3 Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
Accepted: 31 May 2021
We report the first detection in space of the cumulene carbon chain l-H2C5. A total of eleven rotational transitions, with Jup = 7−10 and Ka = 0 and 1, were detected in TMC-1 in the 31.0–50.4 GHz range using the Yebes 40 m radio telescope. We derived a column density of (1.8 ± 0.5)×1010 cm−2. In addition, we report observations of other cumulene carbenes detected previously in TMC-1 in order to compare their abundances with the newly detected cumulene carbene chain. We find that l-H2C5 is ∼4.0 times less abundant than the larger cumulene carbene l-H2C6, while it is ∼300 and ∼500 times less abundant than the shorter chains l-H2C3 and l-H2C4. We discuss the most likely gas-phase chemical routes to these cumulenes in TMC-1 and stress that chemical kinetics studies able to distinguish between different isomers are needed to shed light on the chemistry of CnH2 isomers with n > 3.
Key words: astrochemistry / ISM: molecules / ISM: individual objects: TMC-1 / line: identification / molecular data
© ESO 2021
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