Discovery of Interstellar trans-cyanovinylacetylene (HC≡CCH=CHC≡N) and vinylcyanoacetylene (H2C=CHC3N) in GOTHAM Observations of TMC-1 - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical journal letters Année : 2021

Discovery of Interstellar trans-cyanovinylacetylene (HC≡CCH=CHC≡N) and vinylcyanoacetylene (H2C=CHC3N) in GOTHAM Observations of TMC-1

Résumé

We report the discovery of two unsaturated organic species, trans-(E)-cyanovinylacetylene and vinylcyanoacetylene, using the second data release of the GOTHAM deep survey toward TMC-1 with the 100m Green Bank Telescope. For both detections, we performed velocity stacking and matched filter analyses using Markov Chain Monte Carlo simulations, and for trans-(E)-cyanovinylacetylene, three rotational lines were observed at low signal-to-noise (∼3σ). From this analysis, we derive column densities of 2 × 1011 and 3 × 1011 cm-2 for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of <2 × 1011 cm-2 for trans-(Z)- cyanovinylacetylene. Comparisons with G3//B3LYP semiempirical thermochemical calculations indicate abundances of the [H3C5N] isomers are not consistent with their thermodynamic stability, and instead their abundances are mainly driven by dynamics. We provide a discussion on how these species may be formed in TMC-1, with reference to related molecules like vinyl cyanide (CH2 = CHC ≡ N). As part of this discussion, we performed the same analysis for ethyl cyanide (CH3CH2C≡N), the hydrogenation product of CH2=CHC≡N. This analysis provides evidence-at 4.2σ significance-of an upper limit to the column density of <4×1011 cm-2; an order of magnitude lower than previous upper limits toward this source.

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hal-03195964 , version 1 (31-05-2021)

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K.L.K. Lee, R.A. Loomis, A.M. Burkhardt, Ilsa R. Cooke, C. Xue, et al.. Discovery of Interstellar trans-cyanovinylacetylene (HC≡CCH=CHC≡N) and vinylcyanoacetylene (H2C=CHC3N) in GOTHAM Observations of TMC-1. The Astrophysical journal letters, 2021, 908 (1), pp.abdbb9. ⟨10.3847/2041-8213/abdbb9⟩. ⟨hal-03195964⟩
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