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E ect of Optical Depth on Study of Chemical Properties of Massive Star Forming Clumps
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作者 Jian-jun Zhou Run-xia Li +8 位作者 Donghui Quan Jarken Esimbek Yu-xin He Da-lei Li xin-di tang Gang Wu Wei-guang Ji Zheng-xue Chang Xia Zhang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第1期114-118,共5页
Here we present the study on chemical properties of massive star forming clumps using N2H^+(1-0),H^13CO+(1-0),HCN(1-0)and HN^13C(1-0)data from the literature[Astron.Astrophys.563,A97(2014)].We found that abundances of... Here we present the study on chemical properties of massive star forming clumps using N2H^+(1-0),H^13CO+(1-0),HCN(1-0)and HN^13C(1-0)data from the literature[Astron.Astrophys.563,A97(2014)].We found that abundances of H^13CO+ and HN^13C are a ected by H2 column densities.As the median values of these two abundances increase by nearly 10 times from stages A to B,H^13CO+and HN^13C are suitable for tracing the evolution of massive star forming clumps.The order of rapidity in growth of abundances of all the four studied molecules from stages A to B,is H^13CO^+,HCN,HN^13C,and N2H^+,from the highest to the lowest.Our results suggest that the observing optically thin molecular lines with high angular resolution are necessary to study the chemical evolution of massive star forming clumps. 展开更多
关键词 Stars formation CLUMPS MOLECULES Radio lines
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The comparison of H_2CO(1_(10)–1_(11)),C^(18)O(1–0) and the continuum towards molecular clouds
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作者 xin-di tang Jarken Esimbek +2 位作者 Jian-Jun Zhou Gang Wu Daniel Okoh 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2014年第8期959-970,共12页
We present large scale observations of C^18O (1-0) towards four massive star forming regions: MON R2, S156, DR17/L906 and M17/M18. The transitions of H2CO (110-111), C^18O (1-0) and the 6cm continuum are compa... We present large scale observations of C^18O (1-0) towards four massive star forming regions: MON R2, S156, DR17/L906 and M17/M18. The transitions of H2CO (110-111), C^18O (1-0) and the 6cm continuum are compared in these four regions. Our analysis of the observations and the results of the Non-LTE model shows that the brightness temperature of the formaldehyde absorption line is strongest in a background continuum temperature range of about 3 - 8 K. The excitation of the H2CO absorption line is affected by strong background continuum emission. From a comparison of H2CO and C^18O maps, we found that the extent of H2CO absorption is broader than that of C^18O emission in the four regions. Except for the DR17 region, the maximum in H2CO absorption is located at the same position as the C^18O peak. A good correlation between intensities and widths of H2CO absorption and C^18O emission lines indicates that the H2CO absorption line can trace the dense, warm regions of a molecular cloud. We find that N(H2CO) is well correlated with N( C^18O) in the four regions and that the average ratio of column densities is (N(H2CO)/N(ClSO)) ~0.03. 展开更多
关键词 ISM clouds -- molecules -- stars FORMATION
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