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遅い中性子捕獲反応による重元素合成過程の研究

Research Project

Project/Area Number 17740163
Research Category

Grant-in-Aid for Young Scientists (B)

Allocation TypeSingle-year Grants
Research Field Particle/Nuclear/Cosmic ray/Astro physics
Research InstitutionJapan Atomic Energy Agency

Principal Investigator

岩本 信之  Japan Atomic Energy Agency, 原子力基礎工学研究部門, 研究員 (70391307)

Project Period (FY) 2005 – 2007
Project Status Completed (Fiscal Year 2007)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2007: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2006: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords星の進化 / 中性子捕獲反応 / 重元素合成 / 核データ / s過程 / 恒星進化 / 漸近巨星分枝星
Research Abstract

1.遅い中性子捕獲反応過程(s過程)による元素合成計算を行い、r+s星と分類される星の組成パターンについて研究した。r+s星ではs過程で主に合成されるSr, Y, ZrやBa, La, Ce, Nd、そしてPbなどの元素が観測されている。また、Euの量がs過程で予想される合成量に比べて非常に多いという特徴がある。本研究では、多くの中性子捕獲元素が観測されている12天体の組成パターンと計算結果とを比較することにより、過剰なEuの起源と組成パターンの特徴を調べた。その結果、Euの過剰さはEuやSmの中性子捕獲反応率の不確定性に起因するものではなく、Euなどの重元素を多く含むガスとの混合に因るものであることを明らかにした。そして、Euの過剰さを超新星爆発に起源をもつr過程に因るものであると仮定すると、観測された組成パターンを極めて良く再現できることを示した。また、r過程元素を含むガスとの混合による影響が顕著に現れる元素としてEuの他にOs, Ir, Ptや原子番号Z=41-55の元素があり、r+s星やs-rich星においてこれらの元素の分光観測の重要性を指摘した。
2.捕獲反応率依存性を調べるために、Bao, et. al. (2000)とJENDL-3.3を使用してそれぞれの組成パターンを計算し比較した。その結果、パターンの違いはごく僅かであることを明らかにした。
3.金属欠乏AGB星のモデル計算からリンまでの軽元素の結果を用いて、AGB星表面からこれらの元素の放出量を計算し、伴星の表面組成に与える影響を調べた。その結果、1〜8倍の太陽質量のモデルのほとんどでLiを大量に合成し、伴星でのLi量がビッグバン元素合成で予測される量よりも多くなる可能性を初めて指摘した。また、AGB星から伴星への質量移動により出来たと考えられる星の組成パターン(Li-Si)をこれらのモデルが非常に良く再現できることを示し、観測の無かったF, Naや炭素同位体比の予測を与えた。

Report

(3 results)
  • 2007 Annual Research Report
  • 2006 Annual Research Report
  • 2005 Annual Research Report
  • Research Products

    (18 results)

All 2008 2007 2006

All Journal Article (16 results) (of which Peer Reviewed: 4 results) Presentation (2 results)

  • [Journal Article] Empirical Abundance Scaling Laws and Implications for the Gamma-Process in Core-Collapse Supernovae2008

    • Author(s)
      Takehito Hayakawa
    • Journal Title

      The Astrophysical Journal 印刷中

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Lithium synthesis in low metallicity AGB stars2008

    • Author(s)
      Nobuyuki Iwamoto
    • Journal Title

      Proceedings of International Symposium on Origin of Matter and Evolution of Galaxies (OMEG07) 印刷中

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Spectroscopic Studies of Extremely Metal-poor Stars with the Subaru High-Dispersion Spectrograph. IV. The a-Element-Enhanced Metal-poor Star BS 16934-0022007

    • Author(s)
      Wako Aoki
    • Journal Title

      The Astrophysical Journal 660

      Pages: 747-761

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Relativistic Jets in Population III Supernova and Extremely Metal-Poor Stars2007

    • Author(s)
      Nozomu Tominaga
    • Journal Title

      Proceedings of the International Workshop of Energy Budget in the High Energy Universe

      Pages: 361-364

    • Related Report
      2007 Annual Research Report
  • [Journal Article] New Evaluation of Neutron Nuclear Data for Zinc Isotopes2007

    • Author(s)
      Nobuyuki Iwamoto
    • Journal Title

      Journal of Nuclear Science and Technology 44

      Pages: 1131-1141

    • NAID

      10019316816

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] The Connection between Gamma-Ray Bursts and Extremely Metal-poor Stars : Black Hole-forming Supernovae with Relativistic Jets2007

    • Author(s)
      Tominaga, N.
    • Journal Title

      The Astrophysical Journal Letters 657

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Eu isotope measurements on single SiC grains from the Murchison meteorite : A new probe of s-process conditions in parent Asymptotic Giant Branch stars2006

    • Author(s)
      Terada, K.
    • Journal Title

      New Astronomy Reviews 50

      Pages: 582-586

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Principle of Universality of γ-Process Nucleosynthesis in Core-Collapse Supernova Explosions2006

    • Author(s)
      Hayakawa, T.
    • Journal Title

      The Astrophysical Journal Letters 648

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Chemical Abundances in the Secondary Star of the Black Hole Binary V4641 Sagittarii (SAX J1819.3-2525)2006

    • Author(s)
      Sadakane, K.
    • Journal Title

      Publications of the Astronomical Society of Japan 58

      Pages: 595-604

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Explosive Nucleosynthesis in Different Ye Conditions2006

    • Author(s)
      Iwamoto, N.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 409-411

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Neutron-capture Nucleosynthesis in the He-Flash Convective Zone in Extremely Metal-Poor Stars2006

    • Author(s)
      Nishimura, T.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 455-457

    • Related Report
      2006 Annual Research Report
  • [Journal Article] The Abundance Pattern and Formation of Extremely Meta-Poor Stars2006

    • Author(s)
      Umeda, H.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 65-70

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Eu isotopic analyses of SiC grains from the Murchison Meteorite2006

    • Author(s)
      Terada, K.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 324-329

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Universality of the p-process nucleosynthesis in supernova explosions and scaling laws for p- and s-process nuclei in the solar system abundances2006

    • Author(s)
      Hayakawa, T.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 339-344

    • Related Report
      2006 Annual Research Report
  • [Journal Article] The p-Process in the Carbon Deflagration Model for Type Ia Supernovae and Chronology of the Solar System Formation2006

    • Author(s)
      Kusakabe, M.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 424-426

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Nucleosynthetic Signatures of Pop. III Survivors and the Origin of HE0107-5240 and HE1327-23262006

    • Author(s)
      Suda, T.
    • Journal Title

      Proceedings of the symposium on Origin of Matter and Evolution of Galaxies 2005

      Pages: 59-64

    • Related Report
      2006 Annual Research Report
  • [Presentation] JENDL-4のための金の核データ評価2008

    • Author(s)
      岩本 信之
    • Organizer
      日本原子力学会
    • Place of Presentation
      大阪大学吹田キャンバス
    • Year and Date
      2008-03-26
    • Related Report
      2007 Annual Research Report
  • [Presentation] JENDL-4のためのFP核データ評価;(6)Sn同位体データ2007

    • Author(s)
      岩本 信之
    • Organizer
      日本原子力学会
    • Place of Presentation
      北九州国際会議場
    • Year and Date
      2007-09-27
    • Related Report
      2007 Annual Research Report

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Published: 2005-04-01   Modified: 2016-04-21  

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