Non-Detection of HC${}_{11}$N toward TMC-1: Constraining the Chemistry of Large Carbon-Chain Molecules

Abstract

Bell et al. (1997) reported the first detection of the cyanopolyyne HC${}_{11}$N toward the cold dark cloud TMC-1; no subsequent detections have been reported toward any source. Additional observations of cyanopolyynes and other carbon-chain molecules toward TMC-1 have shown a log-linear trend between molecule size and column density, and in an effort to further explore the underlying chemical processes driving this trend, we have analyzed GBT observations of HC${}_9$N and HC${}_{11}$N toward TMC-1. Although we find an HC${}_9$N column density consistent with previous values, HC${}_{11}$N is not detected and we derive an upper limit column density significantly below that reported in Bell et al. Using a state-of-the-art chemical model, we have investigated possible explanations of non-linearity in the column density trend. Despite updating the chemical model to better account for ion-dipole interactions, we are not able to explain the non-detection of HC${}_{11}$N, and we interpret this as evidence of previously unknown carbon-chain chemistry. We propose that cyclization reactions may be responsible for the depleted HC${}_{11}$N abundance, and that products of these cyclization reactions should be investigated as candidate interstellar molecules.

10 pages, 7 figures, 3 tables, accepted for publication in MNRAS

References in corpus (6)

• The 2014 KIDA network for interstellar chemistry
• Detection of circumstellar CH2CHCN, CH2CN, CH3CCH and H2CS
• A New Reference Chemical Composition for TMC-1
• Molecular Line Observations of a Carbon-Chain-Rich Core L492
• Non-Thermal Continuum toward SGRB2(N-LMH)
• Detection of ${}^{13}C$ Isotopic Species of $H{C}_{7}N$

Cited by in corpus (13)

• Detection of Two Interstellar Polycyclic Aromatic Hydrocarbons via Spectral Matched Filtering
• 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• A protostellar system fed by a streamer of 10,500 au length
• Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH${}_2$CN) in TMC-1
• History of the solar-type protostar IRAS16293-2422 as told by the cyanopolyynes
• Deep K-band observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, non-detection of HC11N, and a search for new organic molecules
• Detection of HC${}_5$N and HC${}_7$N Isotopologues in TMC-1 with the Green Bank Telescope
• Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
• Cyanopolyyne chemistry in the L1544 prestellar core: new insights from GBT observations
• Determination of accurate rest frequencies and hyperfine structure parameters of cyanobutadiyne, HC${}_5$N
• Cyanopolyyne line survey towards high-mass star-forming regions with TMRT
• A Computational Study of the Reaction Cyanoacetylene and Cyano Radical leading to 2-Butynedinitrile and Hydrogen Radical
• First Detection of HC5N in a Class II Disk around TW Hya