A study of C4H3N isomers in TMC-1: line by line detection of HCCCH2CN

Abstract

We present Yebes 40m telescope observations of the three most stable C4H3N isomers towards the cyanopolyyne peak of TMC-1. We have detected 13 transitions from CH3C3N (A and E species), 16 lines from CH2CCHCN, and 27 lines (a-type and b-type) from HCCCH2CN. We thus provide a robust confirmation of the detection of HCCCH2CN and CH2CCHCN in space. We have constructed rotational diagrams for the three species, and obtained rotational temperatures between 4-8 K and similar column densities for the three isomers, in the range (1.5-3)e12 cm-2. Our chemical model provides abundances of the order of the observed ones, although it overestimates the abundance of CH3CCCN and underestimates that of HCCCH2CN. The similarity of the observed abundances of the three isomers suggests a common origin, most probably involving reactions of the radical CN with the unsaturated hydrocarbons methyl acetylene and allene. Studies of reaction kinetics at low temperature and further observations of these molecules in different astronomical sources are needed to draw a clear picture of the chemistry of C4H3N isomers in space.

Accepted for publication in A&A Letters

References in corpus (8)

• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH${}_2$CN) in TMC-1
• Discovery of HC4NC in TMC-1: A study of the isomers of HC3N, HC5N, and HC7N
• Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
• Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
• Tentative detection of HC5NH+ in TMC-1
• Trans-cis molecular photoswitching in interstellar Space
• New molecular species at redshift z=0.89

Cited by in corpus (26)

• Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene and indene
• Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene ($c$-C${}_9$H${}_8$) with GOTHAM Observations of TMC-1
• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• The Composition and Chemistry of Titan's Atmosphere
• Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles
• Discovery of the propargyl radical (CH2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds
• O-bearing complex organic molecules at the cyanopolyyne peak of TMC-1: detection of C2H3CHO, C2H3OH, HCOOCH3, and CH3OCH3
• Discovery of CH2CHCCH and detection of HCCN, HC4N, CH3CH2CN, and, tentatively, CH3CH2CCH in TMC-1
• Discovery of the acetyl cation, CH3CO+, in space and in the laboratory
• An overview of desorption parameters of Volatile and Complex Organic Molecules: A systematic dig on experimental literature
• Discovery of HCCCO and C5O in TMC-1 with the QUIJOTE line survey
• Discovery of five cyano derivatives of propene with the QUIJOTE line survey
• Discovery of CH2CCHC4H and a rigorous detection of CH2CCHC3N in TMC-1 with the QUIJOTE line survey
• Hydrogenation of small aromatic heterocycles at low temperatures
• Discovery of interstellar 3-cyano propargyl radical, CH2CCCN
• Laboratory and astronomical discovery of the cyanovinyl radical H2CCCN
• Detection of deuterated methylcyanoacetylene, CH${}_2$DC${}_3$N, in TMC-1
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1
• New deuterated species in TMC-1: Detection of CH2DC4H with the QUIJOTE line survey
• Chemical variations across the TMC-1 boundary: molecular tracers from translucent phase to dense phase
• A search for the three isomers of cyano-1,3-butadiene in TMC-1: Implications for bottom-up routes involving 1,3-butadiene
• First close-coupling study of the excitation of a large cyclic molecule: collision of c-C5H6 with He
• Laboratory observation and astronomical search of 1-cyano propargyl radical, HCCCHCN
• Piecing together formic acid isomerism in dark clouds. Detection of cis-formic acid in TMC-1 and astrochemical modeling
• Expanding the C${}_3$H${}_6$O${}_2$ Isomeric Interstellar Inventory: Discovery of Lactaldehyde and Methoxyacetaldehyde in G+0.693-0.027