Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores
<jats:p><jats:italic>Context.</jats:italic> The chemical pathways linking the small organic molecules commonly observed in molecular clouds to the large, complex, polycyclic species long suspected of being carriers of the ubiquitous unidentified infrared emission bands remain uncle...
| Main Authors: | , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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EDP Sciences
2022
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| Online Access: | https://hdl.handle.net/1721.1/141105 |
| _version_ | 1826208311167418368 |
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| author | Shingledecker, CN Lee, KLK Wandishin, JT Balucani, N Burkhardt, AM Charnley, SB Loomis, R Schreffler, M Siebert, M McCarthy, MC McGuire, BA |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Shingledecker, CN Lee, KLK Wandishin, JT Balucani, N Burkhardt, AM Charnley, SB Loomis, R Schreffler, M Siebert, M McCarthy, MC McGuire, BA |
| author_sort | Shingledecker, CN |
| collection | MIT |
| description | <jats:p><jats:italic>Context.</jats:italic> The chemical pathways linking the small organic molecules commonly observed in molecular clouds to the large, complex, polycyclic species long suspected of being carriers of the ubiquitous unidentified infrared emission bands remain unclear.</jats:p>
<jats:p><jats:italic>Aims.</jats:italic> To investigate whether the formation of mono- and polycyclic molecules observed in cold cores could form via the bottom-up reaction of ubiquitous carbon-chain species with, for example, atomic hydrogen, a search is made for possible intermediates in data taken as part of the GOTHAM (GBT Observations of TMC-1: Hunting for Aromatic Molecules) project.</jats:p>
<jats:p><jats:italic>Methods.</jats:italic> Markov chain Monte Carlo (MCMC) source models were run to obtain column densities and excitation temperatures. Astrochemical models were run to examine possible formation routes, including (a) a novel grain-surface pathway involving the hydrogenation of C<jats:sub>6</jats:sub>N and HC<jats:sub>6</jats:sub>N, (b) purely gas-phase reactions between C<jats:sub>3</jats:sub>N and both propyne (CH<jats:sub>3</jats:sub>CCH) and allene (CH<jats:sub>2</jats:sub>CCH<jats:sub>2</jats:sub>), and (c) via the reaction CN + H<jats:sub>2</jats:sub>CCCHCCH.</jats:p>
<jats:p><jats:italic>Results.</jats:italic> We report the first detection of cyanoacetyleneallene (H<jats:sub>2</jats:sub>CCCHC<jats:sub>3</jats:sub>N) in space toward the TMC-1 cold cloud using the Robert C. Byrd 100 m Green Bank Telescope. Cyanoacetyleneallene may represent an intermediate between less-saturated carbon chains, such as the cyanopolyynes, that are characteristic of cold cores and the more recently discovered cyclic species, such as cyanocyclopentadiene. Results from our models show that the gas-phase allene-based formation route in particular produces abundances of H<jats:sub>2</jats:sub>CCCHC<jats:sub>3</jats:sub>N that match the column density of 2 × 10<jats:sup>11</jats:sup> cm<jats:sup>−2</jats:sup> obtained from the MCMC source model, and that the grain-surface route yields large abundances on ices that could potentially be important as precursors for cyclic molecules.</jats:p> |
| first_indexed | 2024-09-23T14:03:48Z |
| format | Article |
| id | mit-1721.1/141105 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T14:03:48Z |
| publishDate | 2022 |
| publisher | EDP Sciences |
| record_format | dspace |
| spelling | mit-1721.1/1411052023-06-21T18:50:36Z Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores Shingledecker, CN Lee, KLK Wandishin, JT Balucani, N Burkhardt, AM Charnley, SB Loomis, R Schreffler, M Siebert, M McCarthy, MC McGuire, BA Massachusetts Institute of Technology. Department of Chemistry <jats:p><jats:italic>Context.</jats:italic> The chemical pathways linking the small organic molecules commonly observed in molecular clouds to the large, complex, polycyclic species long suspected of being carriers of the ubiquitous unidentified infrared emission bands remain unclear.</jats:p> <jats:p><jats:italic>Aims.</jats:italic> To investigate whether the formation of mono- and polycyclic molecules observed in cold cores could form via the bottom-up reaction of ubiquitous carbon-chain species with, for example, atomic hydrogen, a search is made for possible intermediates in data taken as part of the GOTHAM (GBT Observations of TMC-1: Hunting for Aromatic Molecules) project.</jats:p> <jats:p><jats:italic>Methods.</jats:italic> Markov chain Monte Carlo (MCMC) source models were run to obtain column densities and excitation temperatures. Astrochemical models were run to examine possible formation routes, including (a) a novel grain-surface pathway involving the hydrogenation of C<jats:sub>6</jats:sub>N and HC<jats:sub>6</jats:sub>N, (b) purely gas-phase reactions between C<jats:sub>3</jats:sub>N and both propyne (CH<jats:sub>3</jats:sub>CCH) and allene (CH<jats:sub>2</jats:sub>CCH<jats:sub>2</jats:sub>), and (c) via the reaction CN + H<jats:sub>2</jats:sub>CCCHCCH.</jats:p> <jats:p><jats:italic>Results.</jats:italic> We report the first detection of cyanoacetyleneallene (H<jats:sub>2</jats:sub>CCCHC<jats:sub>3</jats:sub>N) in space toward the TMC-1 cold cloud using the Robert C. Byrd 100 m Green Bank Telescope. Cyanoacetyleneallene may represent an intermediate between less-saturated carbon chains, such as the cyanopolyynes, that are characteristic of cold cores and the more recently discovered cyclic species, such as cyanocyclopentadiene. Results from our models show that the gas-phase allene-based formation route in particular produces abundances of H<jats:sub>2</jats:sub>CCCHC<jats:sub>3</jats:sub>N that match the column density of 2 × 10<jats:sup>11</jats:sup> cm<jats:sup>−2</jats:sup> obtained from the MCMC source model, and that the grain-surface route yields large abundances on ices that could potentially be important as precursors for cyclic molecules.</jats:p> 2022-03-09T19:21:54Z 2022-03-09T19:21:54Z 2021 2022-03-09T19:17:00Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/141105 Shingledecker, CN, Lee, KLK, Wandishin, JT, Balucani, N, Burkhardt, AM et al. 2021. "Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores." Astronomy and Astrophysics, 652. en 10.1051/0004-6361/202140698 Astronomy and Astrophysics Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf EDP Sciences EDP Sciences |
| spellingShingle | Shingledecker, CN Lee, KLK Wandishin, JT Balucani, N Burkhardt, AM Charnley, SB Loomis, R Schreffler, M Siebert, M McCarthy, MC McGuire, BA Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title | Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title_full | Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title_fullStr | Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title_full_unstemmed | Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title_short | Detection of interstellar H 2 CCCHC 3 N: A possible link between chains and rings in cold cores |
| title_sort | detection of interstellar h 2 ccchc 3 n a possible link between chains and rings in cold cores |
| url | https://hdl.handle.net/1721.1/141105 |
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