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Self-Organization in Star Formation and Internal Structure of Molecular Clouds

Research Project

Project/Area Number 09640318
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Astronomy
Research InstitutionNagoya University

Principal Investigator

HANAWA Tomoyuki  Nagoya University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (50172953)

Project Period (FY) 1997 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
KeywordsStar Formation / Self-Gravity / Self-Organization / Numerical Simulation / Rotation / 連星
Research Abstract

Molecular clouds, in which stars form activcly, contain hierarchical internal structures ; they contain elongated filamentary clouds involving spherical cloud cores in which binaries or triplcts are embedded. This hicrarchical structure is produced when stars are formed by gravitational collapse. In this project we regard the deformation of molecular cloud during its gravitational collapse as self-organization. To understand the physics of gravitational collapse, we performed numerical simulations.
We followed the gravitational collapse of initially either a spherical, filamentnry, or disky cloud in our numerical simulations taking account of self-gravity, inaguctic fields, and rotation. Although we tried various initial models, the numerical rcsults are summarized by similarity solutions characterized by the sound speed of gas. The final product in a numerical simulation depends little on the initial mass, magnetic field, and angular momentum of the cloud. This indicates that the structure of a gravitationally contracting cloud is determined by the balance between the gravity and gas pressure.
The major findings from numerical simulations and theoretical analysis are as follows.
1.A magnetized cloud collapses to form a similar disk irrespectively of its initial magnetic field strength. The density and velocity of the disk is well approximated by a similarity solution having the sound speed as a parameter. 2. A gravitationally contracting disk often deforms into a bar. A gravitationally contracting sphere often deforms into a disk or bar. Since a bar is unstable against fragmentation, it is expected to produce a binary or triplet of stars. 3. A gravitationally collapsing filament is well approximated by a similarity solution.

Report

(3 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report
  • Research Products

    (21 results)

All Other

All Publications (21 results)

  • [Publications] Y.Nakajima: "Clustering of PreMain-Sequence Stars in the Orion,Ophiuchus,Chamaeleon,Vela,and Lupus Star-forming Regions" Astrophys.J.497・2. 721-735 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] T.Kawachi: "Gravitational Collapse of Filamentary Clouds" Publ.Astron.Soc.Japan. 50・6. 577-586 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.Nakamura: "Gravitational Collapse of Isothermal Magnetized Clouds: The Universality of Self-similar Collapse" Astrophys.J.510・1. 274-290 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] K.Nobuta: "Jets from Time-Dependent Accretion Flows onto a Black Hole" Astrophys.J.510・2. 614-630 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] S.M.Miyama: "Numerical Astrophysics" Kluwer, 457 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.Nakamura et al.: "Non-axisymmetric Evolution of Dy-namically Contracting Disks and Its Implication for Bi-nary Formation" Astrophys.J.vol.480, no.1. 701-704 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] T.Hanawa et al.: "Stability of Similarity Solutions for a Gravitationally Contracting Sphere : Convergence to the Larson-Penston Solution" Astrophys.J.vol.484, no.1. 238-244 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] K.Saigo et al.: "Similarity Solution for Formation of A Circumstellar Disk through the Collapse of A Flattened Rotating Cloud" Astrophys.J.vol.493, no.2. 342-350 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Y.Nakajima et al.: "Clustering of PreMain-Sequence Stars in the Orion, Ophiuchus, Chamaeleon, Vela, and Lupus Star-forming Regions" Astrophys.J.vol.497, no.2. 721-735 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] T.Kawachi et al.: "Gravitational Collapse of Filamentary Clouds" Publ.Astron.Soc.Japan. vol.50, no.60. 577-586 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.Nakamura et al.: "Gravitational Collapse of Isother-mal Magnetized Clouds : The Universality of Self-similar Collapse" Astrophys.J.vol.510, no.1. 274-290 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] K.Nobuta et al.: "Jets from Time-Dependent Accretion Flows onto a Black Hole" Astrophys.J.vol.510, no.2. 614-630 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] S.M.Miyama et al (eds.): Numerical Actrophysics. Kluwer, 457 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Y.Nakajima: "Clustering of PreMain-Sequence Stars in the Orion,Ophiuchus,Chamaeleon,Vela,and Lupus Star-forming Regions" Astrophys.J.497・2. 721-735 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] T.Kawachi: "Gravitational Collapse of Filamentary Clouds" Publ.Astron.Soc.Japan. 50・6. 577-586 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] F.Nakamura: "Gravitational Collapse of Isothermal Magnetized Clouds: The Universality of Self-similar Collapse." Astrophys.J.510・1. 274-290 (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] N.Nobuta: "Jets from Time-Dependent Accretion Flows onto a Black Hole" Astrophys.J.510・2. 614-630 (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] S.M.Miyama: "Numerical Astrophysics" Kluwer, 457 (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] F.Nakamura: "Non-axisymmetric Evolution of Dynamically Contracting Disks and Its Implication for Binary Formation" Astrophys.J.480・1. 701-704 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] T.Hanawa: "Stability of Similarity Solutions for a Gravitationally Contracting Sphere:Convergence to the Larson-Penston Solution" Astrophys.J.484・1. 238-244 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] K.Saigo: "Similarity Solution for Formation of A Circumstellar Disk through the Collapse of A Flattened Rotating Cloud" Astrophys.J.493・2. 342-350 (1998)

    • Related Report
      1997 Annual Research Report

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Published: 1998-04-01   Modified: 2016-04-21  

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