A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)?
We conducted observations of multiple HC _3 N ( J = 10−9, 12−11, and 16−15) lines and the N _2 H ^+ ( J = 1−0) line toward a large sample of 61 ultracompact (UC) H ii regions, through the Institut de Radioastronomie Millmétrique 30 m and the Arizona Radio Observatory 12 m telescopes. The N _2 H ^+ J...
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Supplement Series |
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| Online Access: | https://doi.org/10.3847/1538-4365/acafe6 |
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| author | Y. X. Wang J. S. Zhang H. Z. Yu Y. Wang Y. T. Yan J. L. Chen J. Y. Zhao Y. P. Zou |
| author_facet | Y. X. Wang J. S. Zhang H. Z. Yu Y. Wang Y. T. Yan J. L. Chen J. Y. Zhao Y. P. Zou |
| author_sort | Y. X. Wang |
| collection | DOAJ |
| description | We conducted observations of multiple HC _3 N ( J = 10−9, 12−11, and 16−15) lines and the N _2 H ^+ ( J = 1−0) line toward a large sample of 61 ultracompact (UC) H ii regions, through the Institut de Radioastronomie Millmétrique 30 m and the Arizona Radio Observatory 12 m telescopes. The N _2 H ^+ J = 1−0 line is detected in 60 sources and HC _3 N is detected in 59 sources, including 40 sources with three lines, 9 sources with two lines, and 10 sources with one line. Using the rotational diagram, the rotational temperature and column density of HC _3 N were estimated toward sources with at least two HC _3 N lines. For 10 sources with only one HC _3 N line, their parameters were estimated, taking one average value of T _rot . For N _2 H ^+ , we estimated the optical depth of the N _2 H ^+ J = 1−0 line, based on the line intensity ratio of its hyperfine structure lines. Then the excitation temperature and column density were calculated. When combining our results in UC H ii regions and previous observation results on high-mass starless cores, the N (HC _3 N)/ N (N _2 H ^+ ) ratio clearly increases from the region stage. This means that the abundance ratio changes with the evolution of high-mass star-forming regions (HMSFRs). Moreover, positive correlations between the ratio and other evolutionary indicators (dust temperature, bolometric luminosity, and luminosity-to-mass ratio) are found. Thus we propose the ratio of N (HC _3 N)/ N (N _2 H ^+ ) as a reliable chemical clock of HMSFRs. |
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| last_indexed | 2024-03-12T04:35:02Z |
| publishDate | 2023-01-01 |
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| spelling | doaj.art-a51f44e7bf4c442a84fbda1ce5d1151f2023-09-03T09:56:33ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492023-01-0126424810.3847/1538-4365/acafe6A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)?Y. X. Wang0https://orcid.org/0000-0001-9155-0777J. S. Zhang1https://orcid.org/0000-0002-5161-8180H. Z. Yu2https://orcid.org/0000-0002-5634-131XY. Wang3https://orcid.org/0000-0002-5412-352XY. T. Yan4https://orcid.org/0000-0001-5574-0549J. L. Chen5https://orcid.org/0000-0001-8980-9663J. Y. Zhao6Y. P. Zou7https://orcid.org/0000-0002-5230-8010Center for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cnCenter for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cnCenter for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cn; Ural Federal University , 19 Mira Street, 620002 Ekaterinburg, RussiaPurple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences , 10 Yuanhua Road, Nanjing 210023, People’s Republic of ChinaMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, GermanyCenter for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cnCenter for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cnCenter for Astrophysics, Guangzhou University , Guangzhou, 510006, People’s Republic of China ; jszhang@gzhu.edu.cnWe conducted observations of multiple HC _3 N ( J = 10−9, 12−11, and 16−15) lines and the N _2 H ^+ ( J = 1−0) line toward a large sample of 61 ultracompact (UC) H ii regions, through the Institut de Radioastronomie Millmétrique 30 m and the Arizona Radio Observatory 12 m telescopes. The N _2 H ^+ J = 1−0 line is detected in 60 sources and HC _3 N is detected in 59 sources, including 40 sources with three lines, 9 sources with two lines, and 10 sources with one line. Using the rotational diagram, the rotational temperature and column density of HC _3 N were estimated toward sources with at least two HC _3 N lines. For 10 sources with only one HC _3 N line, their parameters were estimated, taking one average value of T _rot . For N _2 H ^+ , we estimated the optical depth of the N _2 H ^+ J = 1−0 line, based on the line intensity ratio of its hyperfine structure lines. Then the excitation temperature and column density were calculated. When combining our results in UC H ii regions and previous observation results on high-mass starless cores, the N (HC _3 N)/ N (N _2 H ^+ ) ratio clearly increases from the region stage. This means that the abundance ratio changes with the evolution of high-mass star-forming regions (HMSFRs). Moreover, positive correlations between the ratio and other evolutionary indicators (dust temperature, bolometric luminosity, and luminosity-to-mass ratio) are found. Thus we propose the ratio of N (HC _3 N)/ N (N _2 H ^+ ) as a reliable chemical clock of HMSFRs.https://doi.org/10.3847/1538-4365/acafe6AstrochemistryStar formationInterstellar mediumInterstellar molecules |
| spellingShingle | Y. X. Wang J. S. Zhang H. Z. Yu Y. Wang Y. T. Yan J. L. Chen J. Y. Zhao Y. P. Zou A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? The Astrophysical Journal Supplement Series Astrochemistry Star formation Interstellar medium Interstellar molecules |
| title | A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? |
| title_full | A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? |
| title_fullStr | A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? |
| title_full_unstemmed | A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? |
| title_short | A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)? |
| title_sort | possible chemical clock in high mass star forming regions n hc3n n n2h |
| topic | Astrochemistry Star formation Interstellar medium Interstellar molecules |
| url | https://doi.org/10.3847/1538-4365/acafe6 |
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