Revealing chemical reactions in high-mass star-forming regions with observations, laboratory experiments, and chemical network simulations

• Project/Area Number: 20K14523
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: National Astronomical Observatory of Japan (2021-2023); Gakushuin University (2020)
• Principal Investigator: 谷口 琴美 国立天文台, 科学研究部, 特任助教 (40865549)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Project Status: Completed (Fiscal Year 2023)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2023: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2022: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2021: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2020: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 星間化学 / 星形成 / 電波天文観測 / 天文学

Outline of Research at the Start

大質量星は銀河の進化や太陽系の形成過程を理解する上で重要だが、その形成過程の研究は中小質量星に比べて遅れている。大質量星周辺のガスの化学組成には天体毎に異なる特徴があると発見され、それは大質量星の形成過程を解明する手がかりとなり得ることがわかってきた。本研究では、この大質量星形成領域における化学的多様性の起源及び大質量星形成過程について、電波天文学的観測手法、室内実験、化学反応ネットワークシミュレーションの3つを統合的に駆使して解明することを目的とする。

Outline of Annual Research Achievements

南米チリにあるAtacama Large Millimeter Submillimeter Array (ALMA)の5つの大質量原始星周囲の炭素鎖分子及び有機分子の高空間分解能データの解析を行った。その結果、炭素鎖分子の一種であるHC5Nを5天体中3天体から検出した。また、その分子の空間分布は、温度が100 K以上の領域をトレースする高励起輝線のメタノール（CH3OH）の空間分布と一致することを示した。CH3CNの輝線の解析から、HC5Nが検出された大質量星のコアの温度は100 K以上であることも確認した。さらに、化学反応ネットワークシミュレーションを用いて、大質量星周囲の炭素鎖分子の生成・破壊メカニズムについて詳細を調べた。25-90 K程度で気相中で生成したHC5Nがダスト表面の氷内部に保持され、温度が100 K以上に達した時に蒸発した時に、観測されたHC5Nの存在量を再現することがわかった。以上の結果より、大質量星周囲の炭素鎖分子の生成メカニズムは低質量星周囲で見つかっていた25-35 Kの領域で起こるWarm Carbon-Chain Chemistry (WCCC)ではなく、より高温での生成による寄与が大きいことを示し、Hot Carbon-Chain Chemistry (HCCC)を提案した。
本研究期間において、主にALMAのデータを用いて、大質量星周囲のコアスケールから円盤スケールにかけての炭素鎖分子の観測を行った。HC3Nの振動励起輝線が、比較的進化の進んだウルトラコンパクト電離水素領域を形成している大質量星周囲の円盤の高温領域をトレースすることを示し、大質量星と低質量・中間質量星周囲の円盤との化学組成の比較も世界で初めて行った。また、炭素鎖分子に関するレビュー論文も受理された。

Research Products

• [Int'l Joint Research] Instituto Nacional de Astrofisica(メキシコ)
• [Int'l Joint Research] University of Virginia/University of Massachusetts(米国)
• [Int'l Joint Research] MPE(ドイツ)
• [Int'l Joint Research] NISER(インド)
• [Int'l Joint Research] Chalmers University of Technology(スウェーデン)
• [Int'l Joint Research] University of Virginia(米国)
• [Int'l Joint Research] MPE(ドイツ)
• [Int'l Joint Research] NISER(インド)
• [Int'l Joint Research] Chalmers University of Technology(スウェーデン)
• [Int'l Joint Research] University of Virginia/NRAO/NASA/JPL(米国)
• [Int'l Joint Research] NISER(インド)
• [Int'l Joint Research] University of Virginia/NASA JPL(米国)
• [Int'l Joint Research] Max-Planck-Institute(ドイツ)
• [Int'l Joint Research] NISER(インド)
• [Int'l Joint Research] Chalmers University of Technology(スウェーデン)
• [Journal Article] Observations of high-order multiplicity in a high-mass stellar protocluster (2024)
  • Author(s): Li Shanghuo、Sanhueza Patricio、Beuther Henrik、Chen Huei-Ru Vivien、Kuiper Rolf、Olguin Fernando A.、Pudritz Ralph E.、Stephens Ian W.、Zhang Qizhou、Nakamura Fumitaka、Lu Xing、Kuruwita Rajika L.、Sakai Takeshi、Henning Thomas、Taniguchi Kotomi、Li Fei
  • Journal Title: Nature Astronomy Volume: 15 Issue: 4 Pages: 1-18
  • DOI: 10.1038/s41550-023-02181-9
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Large-scale Mapping Observations of DCN and DCO⁺ toward Orion KL (2024)
  • Author(s): Kotomi Taniguchi, Prathap Rayalacheruvu, Teppei Yonetsu et al.
  • Journal Title: The Astrophysical Journal Volume: 963 Issue: 1 Pages: 12-12
  • DOI: 10.3847/1538-4357/ad1e5a
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] An Extremely Young Protostellar Core, MMS 1/OMC-3: Episodic Mass Ejection History Traced by the Micro SiO Jet (2024)
  • Author(s): Takahashi Satoko、Machida Masahiro N.、Omura Mitsuki、Johnstone Doug、Saigo Kazuya、Harada Naoto、Tomisaka Kohji、Ho Paul T. P.、Zapata Luis A.、Mairs Steve、Herczeg Gregory J.、Taniguchi Kotomi、Liu Yuhua、Sato Asako
  • Journal Title: The Astrophysical Journal Volume: 964 Issue: 1 Pages: 48-48
  • DOI: 10.3847/1538-4357/ad2268
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Digging into the Interior of Hot Cores with the ALMA (DIHCA). III. The Chemical Link between NH2CHO, HNCO, and H2CO (2023)
  • Author(s): Taniguchi Kotomi、Sanhueza Patricio、Olguin Fernando A.、Gorai Prasanta、Das Ankan、Nakamura Fumitaka、Saito Masao、Zhang Qizhou、Lu Xing、Li Shanghuo、Chen Huei-Ru Vivien
  • Journal Title: The Astrophysical Journal Volume: 950 Issue: 1 Pages: 57-57
  • DOI: 10.3847/1538-4357/acca1d
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Chemical Differentiation around Five Massive Protostars Revealed by ALMA: Carbon-chain Species and Oxygen/Nitrogen-bearing Complex Organic Molecules (2023)
  • Author(s): Taniguchi Kotomi、Majumdar Liton、Caselli Paola、Takakuwa Shigehisa、Hsieh Tien-Hao、Saito Masao、Li Zhi-Yun、Dobashi Kazuhito、Shimoikura Tomomi、Nakamura Fumitaka、Tan Jonathan C.、Herbst Eric
  • Journal Title: The Astrophysical Journal Supplement Series Volume: 267 Issue: 1 Pages: 4-4
  • DOI: 10.3847/1538-4365/acd110
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Digging into the Interior of Hot Cores with ALMA: Spiral Accretion into the High-mass Protostellar Core G336.01?0.82 (2023)
  • Author(s): Olguin Fernando A.、Sanhueza Patricio、Chen Huei-Ru Vivien、Lu Xing、Oya Yoko、Zhang Qizhou、Ginsburg Adam、Taniguchi Kotomi、Li Shanghuo、Morii Kaho、Sakai Takeshi、Nakamura Fumitaka
  • Journal Title: The Astrophysical Journal Letters Volume: 959 Issue: 2 Pages: L31-L31
  • DOI: 10.3847/2041-8213/ad1100
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Vibrationally Excited Lines of HC3N Associated with the Molecular Disk around the G24.78+0.08 A1 Hypercompact H ii Region (2022)
  • Author(s): Taniguchi Kotomi、Tanaka Kei E. I.、Zhang Yichen、Fedriani Ruben、Tan Jonathan C.、Takakuwa Shigehisa、Nakamura Fumitaka、Saito Masao、Majumdar Liton、Herbst Eric
  • Journal Title: The Astrophysical Journal Volume: 931 Issue: 2 Pages: 99-99
  • DOI: 10.3847/1538-4357/ac69d1
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Carbon-chain Chemistry versus Complex-organic-molecule Chemistry in Envelopes around Three Low-mass Young Stellar Objects in the Perseus Region (2021)
  • Author(s): Taniguchi Kotomi、Majumdar Liton、Takakuwa Shigehisa、Saito Masao、Lis Dariusz C.、Goldsmith Paul F.、Herbst Eric
  • Journal Title: The Astrophysical Journal Volume: 910 Issue: 2 Pages: 141-141
  • DOI: 10.3847/1538-4357/abe854
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Chemical Compositions in the Vicinity of Protostars in Ophiuchus (2021)
  • Author(s): Taniguchi Kotomi、Majumdar Liton、Plunkett Adele、Takakuwa Shigehisa、Lis Dariusz C.、Goldsmith Paul F.、Nakamura Fumitaka、Saito Masao、Herbst Eric
  • Journal Title: The Astrophysical Journal Volume: 922 Issue: 2 Pages: 152-152
  • DOI: 10.3847/1538-4357/ac214e
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Optical Properties of Interstellar Dust around the Orion A Molecular Cloud (2021)
  • Author(s): Hayato Uehara, Kazuhito Dobashi, Shingo Nishiura, Tomomi Shimoikura, and Takahiro Naoi
  • Journal Title: The Astrophysical Journal Volume: 915 Issue: 6 Pages: 1540-1555
  • DOI: 10.1093/pasj/psab092
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] 13C Isotopic Ratios of HC3N on Titan Measured with ALMA (2021)
  • Author(s): Iino Takahiro、Taniguchi Kotomi、Sagawa Hideo、Tsukagoshi Takashi
  • Journal Title: The Planetary Science Journal Volume: 2 Issue: 4 Pages: 166-166
  • DOI: 10.3847/psj/ac134c
  • Peer Reviewed / Open Access
• [Journal Article] Carbon Chain Chemistry in Hot-core Regions around Three Massive Young Stellar Objects Associated with 6.7 GHz Methanol Masers (2021)
  • Author(s): Taniguchi Kotomi、Herbst Eric、Majumdar Liton、Caselli Paola、Tan Jonathan C.、Li Zhi-Yun、Shimoikura Tomomi、Dobashi Kazuhito、Nakamura Fumitaka、Saito Masao
  • Journal Title: The Astrophysical Journal Volume: 908 Issue: 1 Pages: 100-100
  • DOI: 10.3847/1538-4357/abd6c9
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Chemical Composition in the IRAS 16562-3959 High-mass Star-forming Region (2020)
  • Author(s): Taniguchi Kotomi、Guzman Andres E.、Majumdar Liton、Saito Masao、Tokuda Kazuki
  • Journal Title: The Astrophysical Journal Volume: 898 Issue: 1 Pages: 54-54
  • DOI: 10.3847/1538-4357/ab994d
  • Peer Reviewed / Int'l Joint Research
• [Presentation] LMT 2millimeter receiver system (B4R): Overview and results of demo-science (2023)
  • Author(s): Kotomi Taniguchi, Ryohei Kawabe, Takeshi Sakai, Bunyo Hatsukade, Kunihiko Tanaka, Akio Taniguchi, Yuki Yoshimura, Tatsuya Takekoshi, Teppei Yonetsu, Masato Hagimoto, Hiroyuki Maezawa, Yoichi Tamura, Kotaro Kohno, David H. Hughes, F. Peter Schloerb, and B4R/LMT Collaboration
  • Organizer: URSI GASS 2023
  • Int'l Joint Research
• [Presentation] Chemical Link among NH2CHO, HNCO, H2CO in High-Mass Protostellar Cores (2023)
  • Author(s): Kotomi Taniguchi, Patricio Sanhueza, Fernando A. Olguin, Prasanta Gorai, Ankan Das, Fumitaka Nakamura, Masao Saito, Qizhou Zhang, Xing Lu, Shanghuo Li, Huei-Ru Vivien Chen
  • Organizer: Astrochemistry Symposium
  • Int'l Joint Research
• [Presentation] Understanding Chemical Differentiation around Five Massive Protostars Revealed by ALMA (2023)
  • Author(s): Kotomi Taniguchi, Liton Majumdar, Paola Caselli, Shigehisa Takakuwa, Masao Saito, Kazuhito Dobashi, Fumitaka Nakamura, Tomomi Shimoikura, Tien-Hao Hsieh, Jonathan C. Tan, Zhi-Yun Li, Eric Herbst
  • Organizer: Planets VII
  • Int'l Joint Research
• [Presentation] Q-band line survey observations toward 12 intermediate-mass protostars with the Yebes 40m telescope (2023)
  • Author(s): Kotomi Taniguchi, Prasanta Gorai, Jonathan C. Tan, Miguel Gomez Garrido, Masao Saito, Fumitaka Nakamura, T. K. Sridharan, & SOFIA Massive Star Formation group
  • Organizer: 日本天文学会秋季大会
• [Presentation] Revealing the Chemical Link among NH2CHO, HNCO, and H2CO using ALMA Observations toward High-Mass Protostellar Cores (2023)
  • Author(s): Kotomi Taniguchi, Patricio Sanhueza, Fernando A. Olguin, Prasanta Gorai, Ankan Das, Fumitaka Nakamura, Masao Saito
  • Organizer: East-Asia ALMA Science Workshop 2023
  • Int'l Joint Research / Invited
• [Presentation] 30-34 GHz Line Survey Observations toward the Serpens South with the eQ Receiver (2023)
  • Author(s): Kotomi Taniguchi, Fumitaka Nakamura, Ryohei Kawabe, Ross Burns, Atsushi Nishimura, Chau-Ching Chiong, Sheng-Yuan Liu, You-Ting Yeh, Shih-Ping Lai, Tomomi Shimoikura, Kazuhito Dobashi, Yoshinori Yonekura, Yasumasa Yamasaki, & eQ-receiver team
  • Organizer: 宇宙電波懇談会シンポジウム2022
• [Presentation] Survey of NH2CHO, HNCO, H2CO, and CH3CN toward high-mass protostars by the DIHCA Project (2023)
  • Author(s): Kotomi Taniguchi, Patricio Sanhueza, Fernando A. Olguin, Prasanta Gorai, Ankan Das, Fumitaka Nakamura, Masao Saito
  • Organizer: 日本天文学会 春季大会
• [Presentation] Carbon-Chain Chemistry around Massive Young Stellar Objects (2022)
  • Author(s): Kotomi Taniguchi
  • Organizer: Dust-Ice-Gas (DIG) Astrochemistry
  • Int'l Joint Research / Invited
• [Presentation] Understanding Chemical Diversity around Massive Young Stellar Objects (2022)
  • Author(s): Kotomi Taniguchi, Liton Majumdar, Paola Caselli, Shigehisa Takakuwa, Masao Saito, Kazuhito Dobashi, Fumitaka Nakamura, Tomomi Shimoikura, Tien-Hao Hsieh, Jonathan C. Tan, Zhi-Yun Li, & Eric Herbst
  • Organizer: From Clouds to Planets II: The Astrochemical Link
  • Int'l Joint Research
• [Presentation] Observational Evidence for Cyanopolyyne Chemistry and Chemical Diversity around Massive Young Stellar Objects (2022)
  • Author(s): Kotomi Taniguchi
  • Organizer: VICO-CICO Workshop 2022
  • Int'l Joint Research / Invited
• [Presentation] Observational Evidence for Cyanopolyyne Chemistry around High-Mass Stars (2022)
  • Author(s): Kotomi Taniguchi, Liton Majumdar, Paola Caselli, Tien-Hao Hsieh, Shigehisa Takakuwa, Masao Saito, Fumitaka Nakamura, Kazuhito Dobashi, Tomomi Shimoikura, Jonathan C. Tan, Zhi-Yun Li, Eric Herbst
  • Organizer: 日本天文学会 秋季大会
• [Presentation] Chemical Survey Observations toward Intermediate-Mass Protostars (2022)
  • Author(s): Kotomi Taniguchi, Miguel Gomez Garrido, Prasanta Gorai, Jonathan C. Tan, Masao Saito, Fumitaka Nakamura, T. K. Sridharan, Liton Majumdar, & SOFIA Massive Star Formation group
  • Organizer: 日本天文学会 秋季大会
• [Presentation] Vibrationally-excited Lines of HC3N Tracing the Disk Structure around the G24.78+0.08 A1 Hyper-compact HII Region (2022)
  • Author(s): 谷口琴美、田中圭、Yichen Zhang、Ruben Fedriani、 Jonathan C. Tan、高桑繁久、中村文隆、齋藤正雄、Liton Majumdar、Eric Herbst
  • Organizer: 日本天文学会2022年春季大会
• [Presentation] 星形成領域における化学プロセスの多様性 -星質量・物理環境との関係- (2022)
  • Author(s): 谷口琴美
  • Organizer: 宇宙電波懇談会シンポジウム2021
  • Invited
• [Presentation] Roles of UV radiation on the chemistry of protostars in the Ophiuchus region (2021)
  • Author(s): Kotomi Taniguchi, Liton Majumdar, Adele Plunkett, Shigehisa Takakuwa, Dariusz C. Liz, Paul F. Goldsmith, Fumitaka Nakamura, Masao Saito, Eric Herbst
  • Organizer: Astrochemical Frontiers 2021
  • Int'l Joint Research
• [Presentation] Nitrile chemistry in a disk structure around the G24.78+0.08 hyper-compact HII region (2021)
  • Author(s): Kotomi Taniguchi, Kei Tanaka, Y. Zhang, R. Fedriani, J. C. Tan, S. Takakuwa, F. Nakamura, M. Saito, L. Majumdar, E. Herbst
  • Organizer: Workshop on Interstellar Matter 2021
  • Int'l Joint Research
• [Presentation] Investigation of roles of the UV radiation on the chemistry around protostars in the Ophiuchus region (2021)
  • Author(s): 谷口琴美、中村文隆、齋藤正雄、Liton Majumdar, Adele Plunkett, 高桑繁久、Dariusz C. Liz, Paul F. Goldsmith, Eric Herbst
  • Organizer: 日本天文学会2021年秋季大会
• [Presentation] A New Type of Carbon Chain Chemistry around Massive Young Stellar Objects (2021)
  • Author(s): Kotomi Taniguchi
  • Organizer: Nobeyama Science Workshop 2020
  • Invited
• [Presentation] ALMA observations of CH3OH and HC3N toward three low-mass young stellar objects in the Perseus region (2021)
  • Author(s): Kotomi Taniguchi, Liton Majumdar, Shigehisa Takakuwa, Masao Saito, Dariusz C. Liz, Paul F. Goldsmith, Eric Herbst
  • Organizer: 日本天文学会 春季大会
• [Presentation] Carbon Chain Chemistry in Hot-Core Regions around Massive Young Stellar Objects (2020)
  • Author(s): Kotomi Taniguchi
  • Organizer: VICO-CICO Workshop 2020
  • Int'l Joint Research / Invited
• [Presentation] Chemical composition in the IRAS 16562-3959 high-mass star-forming region (2020)
  • Author(s): Kotomi Taniguchi, Andres Guzman, Liton Majumdar, Masao Saito, Tokuda Kazuki
  • Organizer: 43rd COSPAR Scientific Assembly 2020
  • Int'l Joint Research
• [Presentation] 星間ダスト表面における光化学反応実験のための装置の立ち上げと初期成果 (2020)
  • Author(s): 谷口琴美、平山朱実、久保崇紀、荒川一郎、山川紘一郎
  • Organizer: 日本天文学会 秋季大会
• [Presentation] 紫外線照射下における一酸化炭素の水素付加反応に関する室内実験 (2020)
  • Author(s): 平山朱実、久保崇紀、永井颯真、谷口琴美、山川紘一郎
  • Organizer: Nobeyama Science Workshop 2020
• [Remarks] Reveal chemical links involving NH2CHO
  • URL: https://sci.nao.ac.jp/main/highlights/20230414
• [Remarks] Discovery of a new type of carbon-chain chemistry
  • URL: https://sci.nao.ac.jp/main/highlights/20230515
• [Remarks] 大質量星が誕生している領域の化学組成と星の進化の過程 －分子で探る重い星が生まれる環境－
  • URL: https://www.univ.gakushuin.ac.jp/about/pr/press/20200723release.html
• [Remarks] 大質量星に照らされた天空のカーボン・チェーン工場；高温領域で形成される「炭素鎖分子」の発見
  • URL: https://www.nro.nao.ac.jp/news/2021/0224-taniguchi.html#nmnews