Interstellar Detection of 2-cyanocyclopentadiene, C 5 H 5 CN, a Second Five-membered Ring toward TMC-1

Kelvin Lee, Kin Long and Changala, P. Bryan and Loomis, Ryan A. and Burkhardt, Andrew M. and Xue, Ci and Cordiner, Martin A. and Charnley, Steven B. and McCarthy, Michael C. and McGuire, Brett A. (2021) Interstellar Detection of 2-cyanocyclopentadiene, C 5 H 5 CN, a Second Five-membered Ring toward TMC-1. The Astrophysical Journal Letters, 910 (1). L2. ISSN 2041-8205

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Abstract

Using radio observations with the Green Bank Telescope, evidence has now been found for a second five-membered ring in the dense cloud Taurus Molecular Cloud-1 (TMC-1). Based on additional observations of an ongoing, large-scale, high-sensitivity spectral line survey (GOTHAM) at centimeter wavelengths toward this source, we have used a combination of spectral stacking, Markov Chain Monte Carlo (MCMC), and matched filtering techniques to detect 2-cyanocyclopentadiene, a low-lying isomer of 1-cyanocyclopentadiene, which was recently discovered there by the same methods. The new observational data also yield a considerably improved detection significance for the more stable isomer and evidence for several individual transitions between 23–32 GHz. Through our MCMC analysis, we derive cospatial, total column densities of 8.3 × 1011 and 1.9 × 1011 cm−2 for 1- and 2-cyanocyclopentadiene, respectively, corresponding to a ratio of ∼4.4 favoring the former. The derived abundance ratios point toward a common formation pathway—most likely being cyanation of cyclopentadiene by analogy to benzonitrile.

Item Type: Article
Subjects: Open Research Librarians > Physics and Astronomy
Depositing User: Unnamed user with email support@open.researchlibrarians.com
Date Deposited: 13 May 2023 08:06
Last Modified: 03 Feb 2024 04:38
URI: http://stm.e4journal.com/id/eprint/950

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