Calculating the Excitation Temperature for H2CO Absorption Lines in Molecular Clouds

作     者：Jia Bu Jarken Esimbek Jianjun Zhou Toktarkhan Komesh Xindi Tang Dalei Li Yuxin He Kadirya Tursun Dongdong Zhou Ernar Imanaly Serikbek Sailanbek 

作者机构：Xinjiang Astronomical ObservatoryChinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Radio AstronomyChinese Academy of Sciences Xinjiang Key Laboratory of Radio Astrophysics Energetic Cosmos LaboratoryNazarbayev University Institute of Experimental and Theoretical PhysicsAl-Farabi Kazakh National University 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究)

年 卷 期：2024年第24卷第7期

页      面：271-274页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：funded by the National Key R&D Program of China under grant No.2022YFA1603103 partially funded by the Regional Collaborative Innovation Project of Xinjiang Uyghur Autonomous Region under grant No.2022E01050 the Tianshan Talent Program of Xinjiang Uygur Autonomous Region under grant No.2022TSYCLJ0005 the Natural Science Foundation of Xinjiang Uygur Autonomous Region under grant No.2022D01E06 the Chinese Academy of Sciences (CAS) Light of West China Program under grants Nos.xbzg-zdsys-202212,2020-XBQNXZ-017,and 2021-XBQNXZ-028 the National Natural Science Foundation of China (NSFC,grant Nos.12173075,11973076,and 12103082) the Xinjiang Key Laboratory of Radio Astrophysics under grant No.2022D04033 the Youth Innovation Promotion Association CAS funded by the Chinese Academy of Sciences Presidents International Fellowship Initiative under grants Nos.2022VMA0019 and 2023VMA0030 funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan under grant No.AP13067768 

主　　题：(ISM:) HII regions ISM: clouds ISM: molecules 

摘      要：The excitation temperature Texfor molecular emission and absorption lines is an essential parameter for interpreting the molecular *** temperature can be obtained by observing multiple molecular transitions or hyperfine structures of a single transition,but it remains unknown for a single transition without hyperfine structure *** H2CO absorption experiments for a single transition without hyperfine structures adopted a constant value of Tex,which is not correct for molecular regions with active star formation and H II *** H2CO,two equations with two unknowns may be used to determine the excitation temperature Texand the optical depthτ,if other parameters can be determined from *** observational data of the4.83 GHz （λ=6 cm） H2CO (110-111) absorption line for three star formation regions,W40,M17 and DR17,have been used to verify this *** distributions of Texin these sources are in good agreement with the contours of the H110α emission of the H II regions in M17 and DR17 and with the H2CO (110-111) absorption in *** distributions of Texin the three sources indicate that there can be significant variation in the excitation temperature across star formation and H II regions and that the use of a fixed （low） value results in misinterpretation.