CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N
We report a systematic study of all known methyl carbon chains toward TMC-1 using the second data release of the GOTHAM survey, as well as a search for larger species. Using Markov Chain Monte Carlo simulations and spectral line stacking of over 30 rotational transitions, we report statistically sig...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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American Astronomical Society
2022
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| Online Access: | https://hdl.handle.net/1721.1/141113 |
| _version_ | 1811075343902048256 |
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| author | Siebert, Mark A Lee, Kin Long Kelvin Remijan, Anthony J Burkhardt, Andrew M Loomis, Ryan A McCarthy, Michael C McGuire, Brett A |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Siebert, Mark A Lee, Kin Long Kelvin Remijan, Anthony J Burkhardt, Andrew M Loomis, Ryan A McCarthy, Michael C McGuire, Brett A |
| author_sort | Siebert, Mark A |
| collection | MIT |
| description | We report a systematic study of all known methyl carbon chains toward TMC-1 using the second data release of the GOTHAM survey, as well as a search for larger species. Using Markov Chain Monte Carlo simulations and spectral line stacking of over 30 rotational transitions, we report statistically significant emission from methylcyanotriacetylene (CH3C7N) at a confidence level of 4.6σ, and use it to derive a column density of ∼1011 cm−2. We also searched for the related species, methyltetraacetylene (CH3C8H), and place upper limits on the column density of this molecule. By carrying out the above statistical analyses for all other previously detected methyl-terminated carbon chains that have emission lines in our survey, we assess the abundances, excitation conditions, and formation chemistry of methylpolyynes (CH3C2nH) and methylcyanopolyynes (CH3C2n-1N) in TMC-1, and compare those with predictions from a chemical model. Based on our observed trends in column density and relative populations of the A and E nuclear spin isomers, we find that the methylpolyyne and methylcyanopolyyne families exhibit stark differences from one another, pointing to separate interstellar formation pathways, which is confirmed through gas–grain chemical modeling with nautilus. |
| first_indexed | 2024-09-23T10:04:33Z |
| format | Article |
| id | mit-1721.1/141113 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T10:04:33Z |
| publishDate | 2022 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1411132023-04-14T18:42:09Z CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N Siebert, Mark A Lee, Kin Long Kelvin Remijan, Anthony J Burkhardt, Andrew M Loomis, Ryan A McCarthy, Michael C McGuire, Brett A Massachusetts Institute of Technology. Department of Chemistry We report a systematic study of all known methyl carbon chains toward TMC-1 using the second data release of the GOTHAM survey, as well as a search for larger species. Using Markov Chain Monte Carlo simulations and spectral line stacking of over 30 rotational transitions, we report statistically significant emission from methylcyanotriacetylene (CH3C7N) at a confidence level of 4.6σ, and use it to derive a column density of ∼1011 cm−2. We also searched for the related species, methyltetraacetylene (CH3C8H), and place upper limits on the column density of this molecule. By carrying out the above statistical analyses for all other previously detected methyl-terminated carbon chains that have emission lines in our survey, we assess the abundances, excitation conditions, and formation chemistry of methylpolyynes (CH3C2nH) and methylcyanopolyynes (CH3C2n-1N) in TMC-1, and compare those with predictions from a chemical model. Based on our observed trends in column density and relative populations of the A and E nuclear spin isomers, we find that the methylpolyyne and methylcyanopolyyne families exhibit stark differences from one another, pointing to separate interstellar formation pathways, which is confirmed through gas–grain chemical modeling with nautilus. 2022-03-10T15:49:46Z 2022-03-10T15:49:46Z 2022-01-01 2022-03-10T15:33:45Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/141113 Siebert, Mark A, Lee, Kin Long Kelvin, Remijan, Anthony J, Burkhardt, Andrew M, Loomis, Ryan A et al. 2022. "CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N." The Astrophysical Journal, 924 (1). en 10.3847/1538-4357/ac3238 The Astrophysical Journal Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf American Astronomical Society The American Astronomical Society |
| spellingShingle | Siebert, Mark A Lee, Kin Long Kelvin Remijan, Anthony J Burkhardt, Andrew M Loomis, Ryan A McCarthy, Michael C McGuire, Brett A CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title | CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title_full | CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title_fullStr | CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title_full_unstemmed | CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title_short | CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N |
| title_sort | ch3 terminated carbon chains in the gotham survey of tmc 1 evidence of interstellar ch3c7n |
| url | https://hdl.handle.net/1721.1/141113 |
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