High spectral resolution observations of HNC3 and HCCNC in the L1544 prestellar core

Abstract

HCCNC and HNC3 are less commonly found isomers of cyanoacetylene, HC3N, a molecule that is widely found in diverse astronomical sources. We want to know if HNC3 is present in sources other than the dark cloud TMC-1 and how its abundance is relative to that of related molecules. We used the ASAI unbiased spectral survey at IRAM 30m towards the prototypical prestellar core L1544 to search for HNC3 and HCCNC which are by-product of the HC3NH+ recombination, previously detected in this source. We performed a combined analysis of published HNC3 microwave rest frequencies with thus far unpublished millimeter data because of issues with available rest frequency predictions. We determined new spectroscopic parameters for HNC3, produced new predictions and detected it towards L1544. We used a gas-grain chemical modelling to predict the abundances of N-species and compare with the observations. The modelled abundances are consistent with the observations, considering a late stage of the evolution of the prestellar core. However the calculated abundance of HNC3 was found 5-10 times higher than the observed one. The HC3N, HNC3 and HCCNC versus HC3NH+ ratios are compared in the TMC-1 dark cloud and the L1544 prestellar core.

Accepted in MNRAS letters. 5 pages plus 2 additional pages for the on-line material

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Cited by in corpus (13)

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• Sulphur chemistry in the L1544 pre-stellar core
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• Detection of Interstellar HC${}_4$NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions
• Isocyanogen formation in the cold interstellar medium
• The nitrogen isotopic ratio of HC3N towards the L1544 prestellar core
• Exploring molecular complexity with ALMA (EMoCA): Complex isocyanides in Sgr B2(N)
• A sensitive 3 mm line survey of L483: a broad view of the chemical composition of a core around a Class 0 object
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Study of the HCCNC and HNCCC isotopologs in TMC-1
• Chemical exploration of Galactic cold cores
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO
• The emergence of molecular complexity in star forming regions as seen with ASAI