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

2023 Fiscal Year Annual Research Report

• Project/Area Number: 20K14523
• Research Institution: National Astronomical Observatory of Japan
• 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
• Keywords: 星間化学 / 星形成 / 電波天文観測

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)
  • Country Name: MEXICO
  • Counterpart Institution: Instituto Nacional de Astrofisica
• [Int'l Joint Research] University of Virginia/University of Massachusetts(米国)
  • Country Name: U.S.A.
  • Counterpart Institution: University of Virginia/University of Massachusetts
• [Int'l Joint Research] MPE(ドイツ)
  • Country Name: GERMANY
  • Counterpart Institution: MPE
• [Int'l Joint Research] NISER(インド)
  • Country Name: INDIA
  • Counterpart Institution: NISER
• [Int'l Joint Research] Chalmers University of Technology(スウェーデン)
  • Country Name: SWEDEN
  • Counterpart Institution: Chalmers University of Technology
• [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 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): Taniguchi Kotomi、Rayalacheruvu Prathap、Yonetsu Teppei、Takekoshi Tatsuya、Hatsukade Bunyo、Kohno Kotaro、Oshima Tai、Tamura Yoichi、Yoshimura Yuki、Gomez-Rivera Victor、Rojas-Garcia Sergio、Gomez-Ruiz Arturo I.、Hughes David H., et al.
  • Journal Title: The Astrophysical Journal Volume: 963 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 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 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 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 Pages: L31～L31
  • DOI: 10.3847/2041-8213/ad1100
  • Peer Reviewed / Open Access / 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
• [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