PMO OpenIR
A Systematic TMRT Observational Study of Galactic C-12/C-13 Ratios from Formaldehyde
Yan, Y. T.1; Zhang, J. S.1; Henkel, C.2,3; Mufakharov, T.4,5; Jia, L. W.1; Tang, X. D.2,6,7; Wu, Y. J.4,7; Li, J.4,7; Zeng, Z. A.1; Wang, Y. X.1; Li, Y. Q.1; Huang, J.1; Jian, J. M.1
2019-06-01
Source PublicationASTROPHYSICAL JOURNAL
ISSN0004-637X
Volume877Issue:2Pages:15
Corresponding AuthorZhang, J. S.(jszhang@gzhu.edu.cn)
AbstractWe present observations of the C-band 1(10)-1(11) (4.8 GHz) and Ku-band 2(11)-2(12) (14.5 GHz) K-doublet lines of H2CO and the C-band 1(10)-1(11) (4.6 GHz) line of (H2CO)-C-13 toward a large sample of Galactic molecular clouds, through the Shanghai Tianma 65 m radio telescope (TMRT). Our sample with 112 sources includes strong H2CO sources from the TMRT molecular line survey at C-band and other known H2CO sources. All three lines are detected toward 38 objects (43 radial velocity components) yielding a detection rate of 34%. Complementary observations of their continuum emission at both C- and Ku-bands were performed. Combining spectral line parameters and continuum data, we calculate the column densities, the optical depths and the isotope ratio (H2CO)-C-12/(H2CO)-C-13 for each source. To evaluate photon trapping caused by sometimes significant opacities in the main isotopologue's rotational mm-wave lines connecting our measured K-doublets, and to obtain C-12/C-13 abundance ratios, we used the RADEX non-LIE model accounting for radiative transfer effects. This implied the use of the new collision rates from Wiesenfeld & Faure. Also implementing distance values from trigonometric parallax measurements for our sources, we obtain a linear fit of C-12/C-13 = (5.08 +/- 1.10)D-GC + (11.86 +/- 6.60), with a con elation coefficient of 0.58. D-GC refers to Galactocentric distances. Our C-12/C-13 C ratios agree very well with the ones deduced from CN and (CO)-O-1-O-8 but are lower than those previously reported on the basis of H2CO, tending to suggest that the bulk of the H2CO in our sources was formed on dust grain mantles and not in the gas phase.
KeywordGalaxy: evolution HII regions ISM: abundances
DOI10.3847/1538-4357/ab17d6
WOS KeywordSTAR-FORMATION REGIONS ; MOLECULAR CLOUDS ; DISTANCE AMBIGUITIES ; DENSE GAS ; H2CO ; ISOTOPE ; C-13 ; GALAXY ; ABUNDANCES ; EXCITATION
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000470807700015
PublisherIOP PUBLISHING LTD
Citation statistics
Cited Times:1[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/26990
Collection中国科学院紫金山天文台
Corresponding AuthorZhang, J. S.
Affiliation1.Guangzhou Univ, Ctr Astrophys, Guangzhou 510006, Guangdong, Peoples R China
2.Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
3.King Abdulaziz Univ, Astron Dept, POB 80203, Jeddah 21589, Saudi Arabia
4.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China
5.Kazan Fed Univ, 18 Kremlyovskaya St, Kazan 420008, Russia
6.Chinese Acad Sci, Xinjiang Astron Observ, Urumqi 830011, Peoples R China
7.Chinese Acad Sci, Key Lab Radio Astron, Beijing, Peoples R China
Recommended Citation
GB/T 7714
Yan, Y. T.,Zhang, J. S.,Henkel, C.,et al. A Systematic TMRT Observational Study of Galactic C-12/C-13 Ratios from Formaldehyde[J]. ASTROPHYSICAL JOURNAL,2019,877(2):15.
APA Yan, Y. T..,Zhang, J. S..,Henkel, C..,Mufakharov, T..,Jia, L. W..,...&Jian, J. M..(2019).A Systematic TMRT Observational Study of Galactic C-12/C-13 Ratios from Formaldehyde.ASTROPHYSICAL JOURNAL,877(2),15.
MLA Yan, Y. T.,et al."A Systematic TMRT Observational Study of Galactic C-12/C-13 Ratios from Formaldehyde".ASTROPHYSICAL JOURNAL 877.2(2019):15.
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