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Comprehensive Survey of Elemental Abundances of Nearby M Dwarfs with Planet Search Data

Research Project

Project/Area Number 21K20388
Research Category

Grant-in-Aid for Research Activity Start-up

Allocation TypeMulti-year Fund
Review Section 0204:Astronomy, earth and planetary science, and related fields
Research InstitutionCenter for Novel Science Initatives, National Institutes of Natural Sciences

Principal Investigator

ISHIKAWA Hiroyuki  大学共同利用機関法人自然科学研究機構(新分野創成センター、アストロバイオロジーセンター、生命創成探究, アストロバイオロジーセンター, 特任研究員 (00910902)

Project Period (FY) 2021-08-30 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2022: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords光赤外線天文学 / 高分散分光 / 化学組成 / 低質量星 / 系外惑星 / M型矮星
Outline of Research at the Start

質量が太陽の約半分以下の恒星であるM型矮星(以下、M型星)を公転する惑星は、2020年代後半の次世代観測装置による生命探査の有望なターゲットである。しかしその惑星の形成過程や内部構造の理解に必要な、M型星自身の元素組成については、統一的な理解がなされていない。本研究はまず、近赤外波長域の高分散スペクトルに基づくM型星の組成決定法を3000 K以下の低温天体に拡張し、連星を利用することでその検証と改良を行う。次に、それを100天体以上の惑星探索データに応用することで、初めて近傍M型星の元素組成について統計的な理解を得る。この成果は、今後M型星周りに見つかる惑星の特徴づけのための重要な土台となる。

Outline of Final Research Achievements

Aiming for a unified understanding of the chemical characteristics of M dwarfs, which is essential for the characterization of planets orbiting M dwarfs, we have conducted the following three steps: (1) to extend and validate the analysis method that has been used only for relatively hot M dwarfs (effective temperature >3000 K) so that they can be applied to cooler M dwarfs, (2) to apply the above methods to 70 M dwarfs observed in the framework of a planet search project IRD-SSP, and (3) to develop an open-source code ExoJAX for calculating and fitting the model spectra taking into account the huge amount of molecular lines.

Academic Significance and Societal Importance of the Research Achievements

人は誰しも、地球生命とは異なる生物について思いを馳せたことがあるだろう。その存在の確認が、近年急速な発展を見せる系外惑星科学の大目標の1つである。晩期M型矮星については、その周りの惑星の検出や特徴づけが現代の技術で可能であることから特に研究が進んでいる。一方でその惑星の正確な特徴づけのためにはM型星自体の化学組成の理解が重要であるが、天体の暗さや、低温ゆえにスペクトルが複雑になる等の問題に阻まれその研究は遅れていた。本研究は、これまでより高温の恒星に対してしか有効でなかった手法を拡張開発し、実際に70天体ものデータに適用したという点で、晩期M型矮星およびその惑星の理解に資する意義が大きい。

Report

(3 results)
  • 2022 Annual Research Report   Final Research Report ( PDF )
  • 2021 Research-status Report
  • Research Products

    (12 results)

All 2023 2022 Other

All Journal Article (5 results) (of which Int'l Joint Research: 5 results,  Peer Reviewed: 5 results,  Open Access: 5 results) Presentation (5 results) (of which Int'l Joint Research: 3 results) Remarks (2 results)

  • [Journal Article] An Earth-sized Planet around an M5 Dwarf Star at 22 pc2023

    • Author(s)
      Hirano Teruyuki、Dai Fei、Livingston John H.、et al.
    • Journal Title

      The Astronomical Journal

      Volume: 165 Issue: 3 Pages: 131-131

    • DOI

      10.3847/1538-3881/acb7e1

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] TOI-1696: A Nearby M4 Dwarf with a 3 R_Earth Planet in the Neptunian Desert2022

    • Author(s)
      Mori Mayuko、Livingston John H.、Leon Jerome de、Narita Norio、Hirano Teruyuki、et al.
    • Journal Title

      The Astronomical Journal

      Volume: 163 Issue: 6 Pages: 298-298

    • DOI

      10.3847/1538-3881/ac6bf8

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] A super-Earth orbiting near the inner edge of the habitable zone around the M4.5 dwarf Ross 5082022

    • Author(s)
      Harakawa Hiroki、Takarada Takuya、Kasagi Yui、Hirano Teruyuki、et al.
    • Journal Title

      Publications of the Astronomical Society of Japan

      Volume: 74 Issue: 4 Pages: 904-922

    • DOI

      10.1093/pasj/psac044

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf2022

    • Author(s)
      Kawauchi K.、Murgas F.、Palle E.、Narita N.、Fukui A.、Hirano T.、et al.
    • Journal Title

      Astronomy & Astrophysics

      Volume: 666 Pages: A4-A4

    • DOI

      10.1051/0004-6361/202243381

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Elemental Abundances of nearby M Dwarfs Based on High-resolution Near-infrared Spectra Obtained by the Subaru/IRD Survey: Proof of Concept2022

    • Author(s)
      Ishikawa Hiroyuki Tako、Aoki Wako、Hirano Teruyuki、et al.
    • Journal Title

      The Astronomical Journal

      Volume: 163 Issue: 2 Pages: 72-72

    • DOI

      10.3847/1538-3881/ac3ee0

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Presentation] 自動微分可能なスペクトルモデルによる M 型矮星の大気リトリーバル2023

    • Author(s)
      石川裕之、河原創、川島由依、増田賢人、小谷隆行、平野照幸、葛原昌幸、Stevanus Nugroho(ABC/NAOJ)、笠木 結
    • Organizer
      日本天文学会春季年会
    • Related Report
      2022 Annual Research Report
  • [Presentation] Auto-differentiable high-resolution spectral model for exoplanets and its application to the Barnard's Star2022

    • Author(s)
      Hiroyuki Tako Ishikawa, Hajime Kawahara, Yui Kawashima, Kento Masuda, Takayuki Kotani, Teruyuki Hirano, Masayuki Kuzuhara, Stevanus K. Nugroho
    • Organizer
      Thinkshop 2022: High-resolution spectroscopy for exoplanet atmospheres and biomarkers
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Extension of verification by binary systems2022

    • Author(s)
      Hiroyuki Tako Ishikawa, Masayuki Kuzuhara, Wako Aoki, Teruyuki Hirano, Takayuki Kotani, Masashi Omiya
    • Organizer
      COOL STARS 21
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Abundance analysis of individual elements for nearby M dwarfs based on high-resolution near-infrared spectra of Subaru/IRD2022

    • Author(s)
      Ishikawa Hiroyuki Tako
    • Organizer
      Subaru Users Meeting FY2021
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research
  • [Presentation] 複数の近赤外高分散分光器を用いた M 型矮星の組成決定 : 連星観測に基づく 検証温度範囲の拡張2022

    • Author(s)
      石川裕之, 葛原昌幸, 青木和光, 小谷隆行, 大宮正士
    • Organizer
      日本天文学会春季年会
    • Related Report
      2021 Research-status Report
  • [Remarks] 惑星探しのデータから、未開拓の低温度星の化学組成を調査

    • URL

      https://www.abc-nins.jp/310/

    • Related Report
      2022 Annual Research Report
  • [Remarks] 自然科学研究機構 アストロバイオロジーセンター 研究成果

    • URL

      https://abc-nins.jp/press/713/

    • Related Report
      2021 Research-status Report

URL: 

Published: 2021-10-22   Modified: 2024-01-30  

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