Letter to the Editor

Discovery of five cyano derivatives of propene with the QUIJOTE line survey^⋆,⋆⋆

¹ Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
e-mail: jose.cernicharo@csic.es
² Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
³ Observatorio Astronómico Nacional (OAN, IGN), Madrid, Spain

Received: 12 June 2022
Accepted: 7 July 2022

Abstract

We report the discovery of five cyano derivatives of propene towards TMC-1 with the QUIJOTE line survey: trans and cis-crotononitrile (t-CH₃CHCHCN, c-CH₃CHCHCN), methacrylonitrile (CH₂C(CH₃)CN), and gauche and cis-allyl cyanide (g-CH₂CHCH₂CN and c-CH₂CHCH₂CN). The observed transitions allowed us to derive a common rotational temperature of 7 ± 1 K for all them. The derived column densities are N(t-CH₃CHCHCN) = (5 ± 0.5) × 10¹⁰ cm⁻², N(c-CH₃CHCHCN) = (1.3 ± 0.2) × 10¹¹ cm⁻², N(CH₂C(CH₃)CN) = (1.0±0.1) × 10¹¹ cm⁻², N(g-CH₂CHCH₂CN) = (8.0 ± 0.8) × 10¹⁰ cm⁻², and N(c-CH₂CHCH₂CN) = (7.0 ± 0.7) × 10¹⁰ cm⁻², respectively. The abundance of cyano-propene relative to that of propene is thus ∼10⁻², which is considerably lower than those of other cyano derivatives of abundant hydrocarbons. Upper limits are obtained for two ethynyl derivatives of propene (E and Z-CH₃CHCHCCH).