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Numerical Study on Evolution from Magnetized Cloud to Protostar Using Three-Dimensional Nested Grid Method

Research Project

Project/Area Number 14540233
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Astronomy
Research InstitutionNational Astronomical Observatory of Japan

Principal Investigator

TOMISAKA Kohji  National Astronomical Observatory, 理論研究部, 教授 (70183879)

Co-Investigator(Kenkyū-buntansha) MATSUMOTO Tomoaki  Hosei University, Faculty of Human Environment, 人間環境学部, 助教授 (60308004)
Project Period (FY) 2002 – 2004
Project Status Completed (Fiscal Year 2004)
Budget Amount *help
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywordsstar formation / interstellar magnetic field / rotation motion / magnetorotational centrifugal wind / binary stars / gravity / fragmentation / 連星・多重星 / 数値計算法
Research Abstract

Using three-dimensional magnetohydrodynamical (NM) simulations, the contraction of the interstellar loud and star formation are studied for the density range from 102 to 1012 cm3.
1. In the nested grid method, a number of grid systems are used. Fine grids cover the high-density center while coarse grids cover the low-density envelope, which guarantees the numerical accuracy in the simulation of self-gravitational collapse. MHD simulation programs (2-dimensional and 3-dimensional) based on the nested grid method was developed, in which the Poisson equation of the self gravity is solved with a multigrid iteration method modified for the nested grid.
2. Axisymmetric 2D simulations show that a disk extending perpendicular to the magnetic field is made and that after the adiabatic core forms at the center with a density of〜10^10 cm-3 gas is ejected perpendicular to the disk owing to the angular momentum transport from the core to the flow.
3. Three-dimensional MHD simulations found three diffe … More rent evolutions for the adiabatic core which will form new-born stars.
(1) Spiral density wave develops in the adiabatic core. High-density (at least two) parts of the arms contract and form binary protostars (spiral fragmentation).
(2) In the isothermal disk, nonaxisymmetric perturbations grow and form bar structure. High-density parts of the bar-shaped adiabatic core collapse by the self-gravity and binary protostars form in the bar (bar fragmentation).
(3) The adiabatic core never fragment and a centrally-peaked core continues to contract and form a single protostar (nofragmentation).
4. Condition for fragmentation is obtained as the ratio of the angular rotation speed to the magnetic flux density is larger than 3 times 10-7 y-1 micro G-1.
5. Even if the initial rotation vector is not parallel to the magnetic field, magnetic field and rotation vector becomes to be aligned each other near the center of the cloud in the course of contraction. A disk runs in the perpendicular direction to the local magnetic field. Less

Report

(4 results)
  • 2004 Annual Research Report   Final Research Report Summary
  • 2003 Annual Research Report
  • 2002 Annual Research Report
  • Research Products

    (18 results)

All 2005 2004 2003 2002 Other

All Journal Article (10 results) Publications (8 results)

  • [Journal Article] Low-Mass Star Formation Triggered by Supernovae in Primordial Clouds2005

    • Author(s)
      M.N.Machida, K.Yomisaka, F.Nakamura, M.Y.Fujimoto
    • Journal Title

      The Astrophysical Journal 622

      Pages: 39-57

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Low-Mass Star Formation Triggered by Supernovae in Primordial Clouds2005

    • Author(s)
      M.N.Machida, K.Tomisaka, F.Nakamura, M.Y.Fujimoto
    • Journal Title

      The Astrophysical Journal 622

      Pages: 39-57

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Journal Article] Molecular Gas Structure around an Active Galactic Nucleus with Nuclear Starburst : Three-Dimensional Non-LTE Calculation of CO Lines2004

    • Author(s)
      K.Wada, K.Tomisaka
    • Journal Title

      The Astrophysical Journal 619

      Pages: 93-104

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Journal Article] Directions of Outflows, Disks, Magnetic Fields, and Rotation of Young Stellar Objects in Collapsing Molecular Cloud Cores2004

    • Author(s)
      T.Matsumoto, K.Tomisaka
    • Journal Title

      The Astrophysical Journal 616

      Pages: 266-282

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] First MHD simulation of collapse and fragmentation of magnetized molecular cloud cores2004

    • Author(s)
      M.N.Machida, K.Tomisaka, T.Matsumoto
    • Journal Title

      Monthly Notices Royal Astronomical Society 348

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Journal Article] Molecular Gas Structure around an Active Galactic Nucleus with Nuclear Starburst: Three-Dimensional Non-LTE Calculation of CO Lines2004

    • Author(s)
      K.Wada, K.Tomisaka
    • Journal Title

      The Astrophysical Journal 619

      Pages: 93-104

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Directions of Outflows, Disks, Magnetic Fields, and Rotation of Young Stellar Obiects in Collapsing Molecular Cloud Cores2004

    • Author(s)
      T.Matsumoto, K.Tomisaka
    • Journal Title

      The Astrophysical Journal 616

      Pages: 266-282

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Fragmentation of a Molecular Cloud Core versus Fragmentation of the Massive Protoplanetary Disk in the Main Accretion Phase2003

    • Author(s)
      T.Matsumoto, T.Hanawa
    • Journal Title

      The Astrophysical Journal 595

      Pages: 913-934

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Journal Article] Collapse of Rotating Magnetized molecular Cloud Cores and Mass Out flows2002

    • Author(s)
      K.Tomisaka
    • Journal Title

      The Astrophysical Journal 575

      Pages: 306-326

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2004 Final Research Report Summary
  • [Journal Article] Collapse of Rotating Magnetized Molecular Cloud Cores and Mass Outflows2002

    • Author(s)
      K.Tomisaka
    • Journal Title

      The Astrophysical Journal 575

      Pages: 306-326

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2004 Annual Research Report 2004 Final Research Report Summary
  • [Publications] Machida, Masahiro N., Tomisaka, Kohji, Matsumoto, Tomoaki: "First MHD simulation of collapse and fragmentation of magnetized molecular cloud cores"Mon.Not.R.Astron.Soc.348,L1(2004). 348. L1-L5 (2004)

    • Related Report
      2003 Annual Research Report
  • [Publications] Tomisaka, K., Machida, M.N., Matsumoto, T., Saigo, K.: "Numerical Simulations of Collapse and Fragmentation of Magnetized Molecular Cloud Cores --- Formation of Binary Systems"Proceedings of "Gravitational Collapse : From Massive Stars to Planets". (印刷中). (2004)

    • Related Report
      2003 Annual Research Report
  • [Publications] Matsumoto, Tomoaki, Hanawa, Tomoyuki: "Fragmentation of a Molecular Cloud Core versus Fragmentation of the Massive Protoplanetary Disk in the Main Accretion Phase"The Astrophysical Journal. 595. 913-934 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Matsumoto, T., Machida, M.N., Tomisaka, K., Hanawa, T.: "Self-gravitational Collapse of a Magnetized Cloud Core : High Resolution Simulations with Three-dimensional MHD Nested Grid"Computer Physics Communications. (印刷中). (2004)

    • Related Report
      2003 Annual Research Report
  • [Publications] Tomisaka, Tomisaka: "Collapse of Rotating Magnetized Cloud Cores and Mass Outflows"The Astrophysical Journal. 575. 306-326 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Machida, Masahiro N., Tomisaka, Kohji, Matsumoto, Tomoaki: "Binary Star Formation and Mass Outflows-MHD Nested Grid Solution"Proceedings of IAU Colloquium #191 : The Environments and Evolution of Double and Multiple Stars. (印刷中). (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] Matsumoto, Tomoaki ; Hanawa, Tomoyuki: "A Fast Algorithm for Solving the Poisson Equation on a Nested Grid"The Astrophysical Journal. 583. 296-307 (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] Saigo, Kazuya, Hanawa, Tomoyuki, Matsumoto, Tomoaki: "Instability of a Protoplanetary Disk in Its Main Accretion Phase"The Astrophysical Journal. 581. 681-693 (2002)

    • Related Report
      2002 Annual Research Report

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Published: 2002-04-01   Modified: 2016-04-21  

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