大型計算機シミュレーションによる星・惑星系の形成過程の理論的研究

2001 年度 実績報告書

• 研究課題/領域番号: 10147105
• 研究機関: 国立天文台
• 研究代表者: 観山 正見 国立天文台, 理論天文学研究系, 教授 (00166191)
• 研究分担者: 中川 義次 神戸大学, 理学部, 教授 (30172282) ; 富阪 幸治 国立天文台, 理論天文学研究系, 教授 (70183879) ; 羽部 朝男 北海道大学, 大学院・理学研究科, 助教授 (90180926) ; 松元 亮治 千葉大学, 理学部, 教授 (00209660) ; 花輪 知幸 名古屋大学, 大学院・理学研究科, 助教授 (50172953)
• キーワード: 数値シミュレーション / 星形成 / 惑星形成 / マゼラン星雲 / 輻射輸送 / 星間ガス雲 / 連星 / 分子雲

研究概要

近年の観測技術の進歩によって星の形成過程や惑星系の母胎である原始惑星系円盤の物理が、構造論的にも進化論的にも観測的に明らかとなっている。それらの構造や進化の観測的事象から、総括的及び普遍的な星・惑星系の形成論の構築に至るためには、基礎物理学の蓄積に基づいた理論的現象の把握が極めて重要となる。この点で、基礎理論を踏まえた数値シミュレーションの実行は、観測との直接比較検討を可能にする上でも、また天体現象を実験的に把握する上でも、現象の理論的解析に極めて有効である。
本年度は平成10年から始まった当特定研究の最終年度に当たり、4年間のそれぞれの分野のまとめ的研究の推進がなされた。それらを踏まえてまとめの研究発表会も行われた。数ある成果の中で、一つのトピックスは、宇宙初期の初代星形成やマゼラン星雲のようなメタル量が極端に少ないガス雲における星形成の研究である。宇宙論的観測が進むにつれて、理論的に初代の星などはいかなる形成過程をたどったのかを解明してきたが、今後は観測への予言をいかに行えるかが焦点と思われる。また、熱的相互作用を含んだ分子雲の形成過程、磁場や回転を伴ったガス雲の収縮過程の研究は、高精度シミュレーションを行って詳細に解明されてきた。特に分子雲レベルから原始星への収縮、円盤の形成、並びに、ジェットの発生といったオーバーオールな星形成過程が追跡できるようになったことは、極めて大きな進展と考えられる。これらの結果と観測との詳細な比較が今後期待される。更に、磁気流体過程のシミュレーションも大幅な進展が達成されたと考える。磁気回転不安定性やジェットのコリメーションといった基礎過程の解明と共に、具体的天体モデルへの応用など観測現象の説明など進展がめざましい。この分野の研究は世界をリードしていて今後のさらなる進展が期待される。惑星形成や原始惑星系円盤の研究成果が推進した。当特定研究の初期には円盤からのスペクトルを説明すると行った大きな成果がもたらされたが、その後も連星系と円盤の相互作用のシミュレーションや円盤内での隕石内物質の形成過程など幅広い研究が行われた。

研究成果

• [文献書誌] Ando, M.: "Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy"Phys.Rev.Lett.,. 86. 3950-3954 (2001)
• [文献書誌] Tagoshi, H.: "First search for gravitational waves from inspiraling compact binaries using TAMA300 data"Phys.Rev.D,. 63. 062001-1-062001-5 (2001)
• [文献書誌] Sano, T.: "Magnetorotational Instability in Protoplanetary Disks.II.Ionization State of the Gas and Unstable Region"The Astrophysical Journal. 543. 486-501 (2000)
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• [文献書誌] Korchagin, V.I.: "On the Origin of Faint Intracluster Starlight in Coma"The Astrophysical Journal. 549. 244-247 (2000)
• [文献書誌] Ito, T.: "An Estimation of Upper Limit Masses of υ Andromedae Planets"The Astrophysical Journal. 552. 372-379 (2000)
• [文献書誌] Sano, T.: "Magnetorotational Instability in Protoplanetary Disks.I.On the Global Stability of Weakly Ionized Disk with Ohmic Dissipation"The Astrophysical Journal. 515. 776-786 (1999)
• [文献書誌] Aikawa, Y.: "Evolution of Molecular Abundance in Proto-planetary Disk with Accretion Flow"The Astrophysical Journal. 519. 705-725 (1999)
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• [文献書誌] K.Tomisaka: "Collapse of Rotating Magnetized Molecular Cloud Core and Mass Outflows"Astrophysical Journal. (submitted). (2001)
• [文献書誌] K.Tomisaka: "Outflow from YSO and Angular Momentum Transfer "The Formation of Bir Stars" ed. H.Zinnecker & R.D.Mathieu"Astronomical Society of the Pacific: San Francisco). 401-405 (2001)
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• [文献書誌] K.Tomisaka: "The Evolution of the Angular Momentum Distribution during Star Formation"The Astrophysical Journal, Letters. 528. L41-L44 (2000)
• [文献書誌] K.Tomisaka: "Outflows from YSO's and the Angular Momentum of New-Born Stars""Star Formation from the Small to the Large Scale" ed. F.Favata (ESA,Noordwijk). 141-148 (2000)
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• [文献書誌] K.Tomisaka: "Gravitational Contraction of Magnetized Clouds"Numerical Astrophysics, eds. S.M.Miyama, K.Tomisaka, & T.Hanawa, (Kluwer Academic Publishers: Dordrecht). 141-150 (1999)
• [文献書誌] S.M.Miyama: "Numerical Astrophysics"Numerical Astrophysics (Dordrecht: Kluwer Academic Publishers). 437 (1999)
• [文献書誌] K.Tomisaka: "Collapse-Driven Outflow in Star-Forming Molecular Cores"The Astrophysical Journal, Letters. 502. 163-167 (1998)
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• [文献書誌] T.Nakamoto: "Minimum Mass of Brown Dwarfs"Planetary Systems in the Universe: Observation, Formation and Evolution, eds A.Penny, P.Artymowicz, A.-M.Lagrange, and S.Russell. (in press). (2001)
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• [文献書誌] T.Nakamoto: "A 3-D Radiative Transfer Solver using a Massively Parallel Computer"Numerical Astrophysics 1998 eds. S.M.Miyama, K.Tomisaka, & T.Hanawa, Kluwer Academic Publishers: Dordrecht. 375-378 (1999)
• [文献書誌] K.Ogochi: "Radiation Hydrodynamical Simulations of Gravitational Collapse of Filamentary Gas Clouds"Numerical Astrophysics 1998 eds. S.M.Miyama, K.Tomisaka, & T.Hanawa, Kluwer Academic Publishers: Dordrecht. 171-172 (1999)
• [文献書誌] N.Kikuchi: "SEDs and IR Images of Disks around YSOs"Numerical Astrophysics 1998 eds. S.M.Miyama, K.Tomisaka, & T.Hanawa, Kluwer Academic Publishers: Dordrecht. 181-182 (1999)
• [文献書誌] T.Nakamoto: "Spectral Modeling of YSOs"Star Formation 1999 ed. T.Nakamoto (Nobeyama Radio Observatory: Nobeyama). 217-220 (1999)
• [文献書誌] N.Kikuchi: "Model Infrared Images and Spectra of Disks around YSOs"Star Formation 1999 ed. T.Nakamoto (Nobeyama Radio Observatory: Nobeyama). 233-234 (1999)
• [文献書誌] K.Ogochi: "The Gravitational Collapse of Filaments : 1D RHD Simulations"Star Formation 1999 ed. T.Nakamoto (Nobeyama Radio Observatory: Nobeyama). 193-194 (1999)
• [文献書誌] A.Iida: "Shock Temperature at a Protoplanetary Disk Surface"Star Formation 1999 ed. T.Nakamoto (Nobeyama Radio Observatory: Nobeyama). 243-244 (1999)
• [文献書誌] T.Hanawa: "Perturbation Growing in the Main Accretion Phase"The Astrophysical Journal. 558, No.2. 753-760 (2001)
• [文献書誌] 花輪 知幸: "星形成の物理"プラズマ・核融合学会誌. 77, No.8. 755-762 (2001)
• [文献書誌] T.Hanawa: "Growth of a Vortex Mode during Gravitational Collapse Resulting in Type II Supernova"The Astrophysical Journal. 540, No.2. 962-968 (2000)
• [文献書誌] N.Fukuda: "Sequential Star Formation Triggered by Expansion of HII Region"The Astrophysical Journal. 533, No.2. 911-923 (2000)
• [文献書誌] K.Saigo: "Collapse of Rotating Gas Cloud and Formation of Protostellar Disk : Effects of Temperature Change during Collapse"The Astrophysical Journal. 531, No.2. 971-987 (2000)
• [文献書誌] T.Hanawa: "Stability of a Dynamically Collapsing Gas Sphere"Publ.Astron.Soc.Japan. 52, No.2. 241-247 (2000)
• [文献書誌] T.Hanawa: "Growth of a Bar Perturbation during Isothermal Collapse"The Astrophysical Journal. 521, No.2. 703-707 (1999)
• [文献書誌] T.Matsumoto: "Bar and Disk Formation in Gravitationally Collapsing Clouds : Implications for Binary Formation"The Astrophysical Journal. 521, No.2. 659-670 (1999)
• [文献書誌] N.Fukuda: "Gravitational and Parametric Instabilities of the Interstellar Medium in Which the Alfven Wave Travels"The Astrophysical Journal. 517, No.1. 226-241 (1999)
• [文献書誌] K.Nobuta: "Jets from Time-Dependent Accretion Flows onto a Black Hole"The Astrophysical Journal. 510, No.2. 614-630 (1999)
• [文献書誌] F.Nakamura: "Gravitational Collapse of Isothermal Magnetized Clouds : The Universality of Sensimilar Collapse"The Astrophysical Journal. 510, No.1. 274-290 (1999)
• [文献書誌] 花輪 知幸: "星形成"活動する宇宙 ed. 柴田 一成、福江 純、松元 亮治、嶺重 慎,(裳華房,東京). 79-100 (1999)
• [文献書誌] N.Fukuda: "Triggered Star Formation in Filamentary Molecular Cloud"Star Formation 1999, Proceedings of Star Formation 1999, held in Nagoya, Japan, June 21-25,1999, Editor: T.Nakamoto, (Nobeyama Radio Observatory, Nobeyama). 369-370 (1999)
• [文献書誌] T.Matsumoto: "Deformation of a Gravitationally Collapsing Molecular Cloud Core : Bar and Disk Formation Followed by Binary Formation"Star Formation 1999, Proceedings of Star Formation 1999, held in Nagoya, Japan, June 21-25,1999, Editor: T.Nakamoto, (Nobeyama Radio Observatory, Nobeyama). 201-202 (1999)
• [文献書誌] K.Saigo: "Collapse of Rotating Gas Cloud and Formation of Protostellar Disk : Effects of Temperature Change during Collapse"Star Formation 1999, Proceedings of Star Formation 1999, held in Nagoya, Japan, June 21-25,1999, Editor: T.Nakamoto, (Nobeyama Radio Observatory, Nobeyama). 195-196 (1999)
• [文献書誌] T.Hanawa: "Bar Mode Instability in Gravitational Collapsing Cloud Core"Star Formation 1999, Proceedings of Star Formation 1999, held in Nagoya, Japan, June 21-25,1999, Editor: T.Nakamoto, (Nobeyama Radio Observatory, Nobeyama). 201-202 (1999)
• [文献書誌] N.Fukuda: "A Second Order Accurate Numerical Scheme for MHD Equations"Numerical Astrophysics : Proceedings of the International Conference on Numerical Astrophysics 1998 (NAP98) Edited by Shoken M.Miyama, Kohji Tomisaka, and Tomoyuki Hanawa,(Kluwer, Dordrecht). 387-388 (1999)
• [文献書誌] K.Nobuta: "Jets from Time-Dependent Accretion Flows onto a Black Hole"Numerical Astrophysics : Proceedings of the International Conference on Numerical Astrophysics 1998 (NAP98), Edited by Shoken M.Miyama, Kohji Tomisaka, and Tomoyuki Hanawa,(Kluwer, Dordrecht). 219-220 (1999)
• [文献書誌] T.Hanawa: "Gravitational Collapse of a Filamentary Molecular Cloud Triggered by HII Region"Numerical Astrophysics : Proceedings of the International Conference on Numerical Astrophysics 1998 (NAP98) Edited by Shoken M.Miyama, Kohji Tomisaka, and Tomoyuki Hanawa,(Kluwer, Dordrecht). 173-174 (1999)
• [文献書誌] K.Saigo: "Dynamical Contraction of Rotating Polytropic Gas Disk"Numerical Astrophysics : Proceedings of the International Conference on Numerical Astrophysics 1998 (NAP98) Edited by Shoken M.Miyama, Kohji Tomisaka, and Tomoyuki Hanawa,(Kluwer, Dordrecht). 173-174 (1999)
• [文献書誌] T.Matsumoto: "Gravitational Collapse of Rotating Clouds : Bar and Disk Formation in a Self-Similar Contracting Clouds"Numerical Astrophysics : Proceedings of the International Conference on Numerical Astrophysics 1998 (NAP98) Edited by Shoken M.Miyama, Kohji Tomisaka, and Tomoyuki Hanawa,(Kluwer, Dordrecht). 151-154 (1999)
• [文献書誌] T.Kawachi: "Gravitational Collapse of Filamentary Clouds"Publ.Astron.Soc.Japan. 50, No.6. 577-586 (1998)
• [文献書誌] Y.Nakajima: "Clustering of Pre-Main Sequence Stars in the Orion, Ophiuchus, Chamaeleon, Vela and Lupus Star Forming Regions"The Astrophysical Journal. 497, No.2. 721-735 (1998)
• [文献書誌] Masako Yamada: "Dynamical Effect by Grobal Thermal Instability of Shock-compressed Gas Slab"The Astrophysical Journal. 547. 99-108 (2001)
• [文献書誌] Ryoichi Nishi: "On the Decelerating Shock Instability of Plane-Palallel Slab with Finite Thickness"The Astrophysical Journal. 532. 1172-1180 (2000)
• [文献書誌] Hideyuki Kamaya: "Dyanamical Instability During Plasma Drift"The Astrophysical Journal. 534. 309-316 (2000)
• [文献書誌] Motomichi Tashiro: "On the Thermal Instability in a Contracting Gas Cloud and Formation of a Bound Cluster"The Astrophysical Journal. 536. 277-283 (2000)
• [文献書誌] Ryoichi Nishi: "Self-Regulation of Star Formation in Low Metallicity Clouds"The Astrophysical Journal. 537. 50-54 (2000)
• [文献書誌] Hideyuki Kamaya: "Frozen Condition for the Charged particles in Molecular Clouds"The Astrophysical Journal. 543. 257-270 (2000)
• [文献書誌] Tetsuya Shiromizu: "Back Reaction to the Spectrum of Magnetic Field in the Kinetic Dynamo Theory"Progress of Theoretical Physics. 101. 39-45 (1999)
• [文献書誌] Kazuyuki Omukai: "Photodissociative Regulation of Star Formation in Metal-free Pregalactic Clouds"The Astrophysical Journal. 518. 64-68 (1999)
• [文献書誌] Ryoichi Nishi: "Formation and Disruption of Cosmological Low Mass Objects"The Astrophysical Journal,Letters. 523. L103-L107 (1999)
• [文献書誌] Kunihito Ioka: "Keplar Rotation Effects on Binary Microlensing Events"Progress of Theoretical Physics. 102. 983-1000 (1999)
• [文献書誌] Ryoichi Nishi: "Dark Matter Search with Gravitational Microlensing Events"Progress of Theoretical Physics Supplement(1999). No.133. 211-231 (1999)
• [文献書誌] Hideyuki Kamaya: "Comments on Alfven Waves and Plasma Drift in a Slightly Ionized Gas"The Astrophysical Journal. 500. 257-261 (1998)
• [文献書誌] Kazuyuki Omukai: "Evolution of Primordial Protostellar Clouds : Quasi-static Analysis"Progress of Theoretical Physics. 99. 747-761 (1998)
• [文献書誌] Takashi Nakamura: "Expected EAGLE event rate towards the Magellanic Clouds"Progress of Theoretical Physics. 99. 963-970 (1998)
• [文献書誌] Hajime Susa: "The Thermal Evolution of the Postshock Layer in Pregalactic Clouds"Progress of Theoretical Physics. 100. 63-77 (1998)
• [文献書誌] Masako Yamada: "Fragmentation of Shock Compressed Sheet of Primordial Gas"The Astrophysical Journal. 505. 148-158 (1998)
• [文献書誌] Kazuyuki Omukai: "Formation of Primordial Protostars"The Astrophysical Journal. 508. 141-150 (1998)
• [文献書誌] Ryoichi Nishi: "Thermal and Dynamical Evolution of Primordial Gas Clouds : on the Formation on First Luminous Objects(Invited Paper)"Progress of Theoretical Physics. 100. 881-903 (1998)
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• [文献書誌] K.Moriwaki: "Stability of a Planet in a Binary System : MACHO-97-BLG-41 Planetary System"Bull.American Astron.Soc.. 33. 112-113 (2001)
• [文献書誌] I.Firuya: "Formation of Planetesimals through Gravitational Fragmentation of a Dust Layer : Initial Masses of Planetesimals"Bull.American Astron.Soc.. 33. 1059 (2001)
• [文献書誌] A.Iida: "A Shock Heating Model for Chondrule Formation in a Protoplanetary Disk"Icarus. 153. 430-450 (2001)
• [文献書誌] S.V.W.Beckwith: "Dust Properties and Assembly of Large Particles in Protoplanetary Disks"Protostars and Planets. IV. 534-555 (2000)
• [文献書誌] H.Takeda: "Gas Drag on a Rotating body with Gravity"Progress of Theoretical Physics. 104. 955-970 (2000)
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• [文献書誌] Y.Sato: "Spectral Energy Distributions of Protoplanetary Disks : Effects of Growth and Settling of Dust Particles"Star Formation 1999 (T.Nakamoto, Ed.). 235-236 (1999)
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• [文献書誌] K.K.Tanaka: "Shock Heating due to Accretion of a Clumpy Cloud onto a Protoplanetary Disk"Icarus. 134. 137-154 (1998)
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• [文献書誌] S.M.Miyama: "Numerical Astrophysics"Kluwer Academic Publishers: Dordrecht. 437 (1999)