Calculating the Excitation Temperature for H2CO Absorption Lines in Molecular Clouds

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外文摘要：The excitation temperature Tex for molecular emission and absorption lines is an essential parameter for interpreting the molecular environment.This 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 lines.Earlier 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 Ⅱregions.For H2CO,two equations with two unknowns may be used to determine the excitation temperature Tex and the optical depth τ,if other parameters can be determined from measurements.Published observational data of the 4.83 GHz(λ=6 cm)H2CO(110-111)absorption line for three star formation regions,W40,M17 and DR17,have been used to verify this method.The distributions of Tex in 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(1 10-1 11)absorption in W40.The distributions of Tex in the three sources indicate that there can be significant variation in the excitation temperature across star formation and H n regions and that the use of a fixed(low)value results in misinterpretation.

外文关键词：

ISM:molecules(ISM:)HⅡ regionsISM: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

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作者单位：

Xinjiang Astronomical Observatory,Chinese Academy of Sciences,Urumqi 830011,China

University of Chinese Academy of Sciences,Beijing 100080,China

Key Laboratory of Radio Astronomy,Chinese Academy of Sciences,Urumqi 830011,China

Xinjiang Key Laboratory of Radio Astrophysics,Urumqi 830011,China

Energetic Cosmos Laboratory,Nazarbayev University,Astana 010000,Kazakhstan

Institute of Experimental and Theoretical Physics,Al-Farabi Kazakh National University,Almaty 050040,Kazakhstan

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基金：

National Key R&D Program of ChinaRegional Collaborative Innovation Project of Xinjiang Uyghur Autonomous RegionTianshan Talent Program of Xinjiang Uygur Autonomous RegionNatural Science Foundation of Xinjiang Uygur Autonomous RegionChinese Academy of Sciences(CAS)Light of West China ProgramChinese Academy of Sciences(CAS)Light of West China ProgramChinese Academy of Sciences(CAS)Light of West China ProgramNational Natural Science Foundation of China(NSFC)National Natural Science Foundation of China(NSFC)National Natural Science Foundation of China(NSFC)Xinjiang Key Laboratory of Radio AstrophysicsYouth Innovation Promotion Association CASChinese Academy of Sciences Presidents International Fellowship InitiativeChinese Academy of Sciences Presidents International Fellowship InitiativeScience Committee of the Ministry of Science and Higher Education of the Republic of KazakhstanOperation,Maintenance,and Upgrading Fund for Astronomical Telescopes and Facility InstrumentsMinistry of Finance of ChinaCASNASA Astrophysics Data System(ADS)

项目编号：

2022YFA16031032022E010502022TSYCLJ00052022D01E06xbzgzdsys-2022122020-XBQNXZ-0172021-XBQNXZ-0281217307511973076121030822022D040332022VMA00192023VMA0030AP13067768

出版年：

2024

DOI：

10.1088/1674-4527/ad5b36

天文和天体物理学研究

中国科学院国家天文台

天文和天体物理学研究

CSTPCD

影响因子：0.406

ISSN：1674-4527

年,卷(期)：2024.24(7)