1991 Fiscal Year Annual Research Report

激変星における降着円盤の不安定性の研究

Research Project

Project/Area Number	01460008
Research Institution	University of Tokyo
Principal Investigator	尾崎洋二東京大学, 理学部, 教授 (30011547)
Co-Investigator(Kenkyū-buntansha)	柴橋博資東京大学, 理学部, 助手 (30126081)
Keywords	降着円盤 / 激変星 / 矮新星 / 不安定性 / 潮汐効果 / 固有値問題 / SU UMa型星 / 数値シミュレ-ション
Research Abstract	本研究の目的は激変星における爆発現象を降着円盤の不安定性により説明することである。すでに、平成元年度、平成2年度の報告書で述べたように、降着円盤の不安定性としては熱不安定性と潮汐不安定性の二種類があり、この二種類の不安定性について詳しく研究した。本年度はSU UMa型の矮新星で観測されるス-パ-ハンプ現象を説明する降着円盤の潮汐不安定性について研究を行った。研究結果は以下のようである。 1.降着円盤の潮汐不安定性と関連して降着円盤の2次元流体シミュレ-ションを実行した。平成元年度に行った数値シミュレ-ションでは、粘着粒子法と呼ばれる流体の圧力項を無視した簡単な手法を使用した。本年度の研究では、圧力の効果も取り入れたSPH法と呼ばれる流体コ-ドを開発し、降着円盤のシミュレ-ションを行った。SPH法でも連星系の質量比が小さい場合、潮汐不安定性が起こり、降着円盤が離心楕円円盤に変形することを確認した。 2.潮汐不安定性によって出来る離心楕円円盤の才差周期について考察した。これを、降着円盤におけるm=1の一本腕固有振動モ-ドの固有値問題として定式化した。この固有値問題はSturmーLiouville型の2階微分方程式に帰されることが示された。そして、この固有値を数値的に求め、2次元数値シミュレ-ションで求められた才差周期と比較した。 3.2次元流体計算で、連星系の伴星からの質量流入量が急増した場合の数値シミュレションを行った。これは、Whitehurst and King(1991)が主張する「質量流入量急増モデル」を検討するためである。シミュレ-ションの結果、質量流入量の急増はかえって潮汐不安定性を妨げる方向に働くことが明らかになった。

Research Products
(22 results)

All Other

All Publications (22 results)

[Publications] Y. Osaki: "A Model for the Superoutburst Phenomenon of SU UMa Stars." Publ.Astron.Soc.Japan. 41. 1005-1033 (1989)
[Publications] Y. Osaki: "Thermal and Tidal Instabilities in Accretion Disks of Dwarf Novae." Theory of Accretion Disks,ed. F.Meyer et al.(Kluwer Academic Publ.). 183-205 (1989)
[Publications] M. Hirose: "Hydrodynamic Simulation of Accretion Disks in Cataclysmic Variables." Theory of Accretion Disks,ed. F.Meyer et al.(Kluwer Academic Publ.). 207-212 (1989)
[Publications] M. Hirose: "Hydrodynamic Simulations of Accretion Disks in Cataclysmic Variables:Superhump Phenomenon in SU UMa Stars." Publ.Astron.Soc.Japan. 42. 135-163 (1990)
[Publications] Y. Osaki: "Excitation Mechanisms of Solar Oscillations." Progress of Seismology of the Sun and Stars,ed. Y.Osaki and H.Shibahashi(SpringerーVerlag). 75-86 (1990)
[Publications] P. Szkody: "Ginga Observations of the Dwarf Novae BV Pup and V426 Oph." Astron.J.100. 546-553 (1990)
[Publications] S.M. Jefferies: "Characteristics of Intermediate Solar pーMode Line Widths." Astrophys.J.377. 330-336 (1991)
[Publications] Y. Osaki: "Superoutburst Phenomenon of the SU UMaーtype Dwarf Novae." Proc.IAU Colloq.No.129,Structure and Emission Properties of Accretion Disks,eds. C. Bertout et al.(Edition Frontieres,Paris). 271-274 (1991)
[Publications] U. Lee: "Viscous Excretion Discs around Be Stars." Mon.Not.Royal astr.Soc.250. 432-437 (1991)
[Publications] M. Hirose: "ThreeーDimentional Structure of Accretion Disks in Close Binary Systems." to appear in Publ.Astron.Soc.Japan. 43. (1991)
[Publications] S. Ichikawa: "Time Evolution of Accretion Disk Radius in Dwarf Novae." to appear in Publ.Astron.Soc.Japan. 44. (1992)
[Publications] T. Sekii: "An Asymptotic Inversion Method of Inferring the Sound Velocity Distribution in the Sun from pーMode Oscillations Spectrum." Publ.Astron.Soc.Japan. 42. 311-331 (1989)
[Publications] H. Shibahashi: "Introductory Review of Oscillations of the Sun and Stars" Progress of Seismology of the Sun and Stars eds. Y. Osaki & H. Shibahashi (SpringerーVerlag). 2-22 (1990)
[Publications] S.V. Vorontsov: "Secondーorder Asymptotic Inversions of the Sound Speed Inside the Sun." Progress of Seismology of the Sun and Stars eds. Y. Osaki & H. Shibahashi(SpringerーVerlag). 325-328 (1990)
[Publications] D.W. Kurtz: "A Frequency Analysis with 20ー400 pHz Accuracy of Five Years of Observations of the l=1 Oscillation in the Rapidly Oscillating Ap Star HR 3831." Mon.Not.Roy.astr.Soc.247. 558-572 (1990)
[Publications] H. Shibahashi: "Attempts to Infer the Density Dsitribution in the Outer Part of the Sun from pーMode Oscillation Spectrum." Solar Phys.133. 117-125 (1990)
[Publications] H. Shibahashi: "Implication of the l Dependence and the Frequency Dependence of Longーterm Frequency Variation." Challenges to Theories of the Structure of Moderate Mass Stars,eds. D.O. Gough & J. Toomre(SpringerーVerlag). 101-110 (1991)
[Publications] H. Shibahashi: "Theoretical Aspects of Asteroseismology of the Rapidly Oscillating Ap Stars." Challenges to Theories of the Structure of Moderate Mas Stars,eds. D.O. Gough & J. Toomre(SpringerーVerlag). 393-410 (1991)
[Publications] S.V. Vorontsov: "Asymptotic Inversion of the Solar Oscillation Frequencies:Sound Speed in the Solar Interior." Publ.Astron.Soc.Japan. 43. 739-753 (1991)
[Publications] P.C. Hansen: "The Modified TruncatedーSVD Method for Regularization in General Form." J.SIAM,in press. (1991)
[Publications] W. Unno: "Nonradial Oscillation of Stars(Second Edition)." University of Tokyo Press, 420 (1989)
[Publications] Y. Osaki: "Progress of Seismology of the Sun and Stars,Lecture Notes in Physics" SpringerーVerlag, 467 (1990)

1991 Fiscal Year Annual Research Report

激変星における降着円盤の不安定性の研究

Principal Investigator

尾崎 洋二 東京大学, 理学部, 教授 (30011547)

Research Products

[Publications] Y. Osaki: "A Model for the Superoutburst Phenomenon of SU UMa Stars." Publ.Astron.Soc.Japan. 41. 1005-1033 (1989)

[Publications] Y. Osaki: "Thermal and Tidal Instabilities in Accretion Disks of Dwarf Novae." Theory of Accretion Disks,ed. F.Meyer et al.(Kluwer Academic Publ.). 183-205 (1989)

[Publications] M. Hirose: "Hydrodynamic Simulation of Accretion Disks in Cataclysmic Variables." Theory of Accretion Disks,ed. F.Meyer et al.(Kluwer Academic Publ.). 207-212 (1989)

[Publications] M. Hirose: "Hydrodynamic Simulations of Accretion Disks in Cataclysmic Variables:Superhump Phenomenon in SU UMa Stars." Publ.Astron.Soc.Japan. 42. 135-163 (1990)

[Publications] Y. Osaki: "Excitation Mechanisms of Solar Oscillations." Progress of Seismology of the Sun and Stars,ed. Y.Osaki and H.Shibahashi(SpringerーVerlag). 75-86 (1990)

[Publications] P. Szkody: "Ginga Observations of the Dwarf Novae BV Pup and V426 Oph." Astron.J.100. 546-553 (1990)

[Publications] S.M. Jefferies: "Characteristics of Intermediate Solar pーMode Line Widths." Astrophys.J.377. 330-336 (1991)

[Publications] Y. Osaki: "Superoutburst Phenomenon of the SU UMaーtype Dwarf Novae." Proc.IAU Colloq.No.129,Structure and Emission Properties of Accretion Disks,eds. C. Bertout et al.(Edition Frontieres,Paris). 271-274 (1991)

[Publications] U. Lee: "Viscous Excretion Discs around Be Stars." Mon.Not.Royal astr.Soc.250. 432-437 (1991)

[Publications] M. Hirose: "ThreeーDimentional Structure of Accretion Disks in Close Binary Systems." to appear in Publ.Astron.Soc.Japan. 43. (1991)

[Publications] S. Ichikawa: "Time Evolution of Accretion Disk Radius in Dwarf Novae." to appear in Publ.Astron.Soc.Japan. 44. (1992)

[Publications] T. Sekii: "An Asymptotic Inversion Method of Inferring the Sound Velocity Distribution in the Sun from pーMode Oscillations Spectrum." Publ.Astron.Soc.Japan. 42. 311-331 (1989)

[Publications] H. Shibahashi: "Introductory Review of Oscillations of the Sun and Stars" Progress of Seismology of the Sun and Stars eds. Y. Osaki & H. Shibahashi (SpringerーVerlag). 2-22 (1990)

[Publications] S.V. Vorontsov: "Secondーorder Asymptotic Inversions of the Sound Speed Inside the Sun." Progress of Seismology of the Sun and Stars eds. Y. Osaki & H. Shibahashi(SpringerーVerlag). 325-328 (1990)

[Publications] D.W. Kurtz: "A Frequency Analysis with 20ー400 pHz Accuracy of Five Years of Observations of the l=1 Oscillation in the Rapidly Oscillating Ap Star HR 3831." Mon.Not.Roy.astr.Soc.247. 558-572 (1990)

[Publications] H. Shibahashi: "Attempts to Infer the Density Dsitribution in the Outer Part of the Sun from pーMode Oscillation Spectrum." Solar Phys.133. 117-125 (1990)

[Publications] H. Shibahashi: "Implication of the l Dependence and the Frequency Dependence of Longーterm Frequency Variation." Challenges to Theories of the Structure of Moderate Mass Stars,eds. D.O. Gough & J. Toomre(SpringerーVerlag). 101-110 (1991)

[Publications] H. Shibahashi: "Theoretical Aspects of Asteroseismology of the Rapidly Oscillating Ap Stars." Challenges to Theories of the Structure of Moderate Mas Stars,eds. D.O. Gough & J. Toomre(SpringerーVerlag). 393-410 (1991)

[Publications] S.V. Vorontsov: "Asymptotic Inversion of the Solar Oscillation Frequencies:Sound Speed in the Solar Interior." Publ.Astron.Soc.Japan. 43. 739-753 (1991)

[Publications] P.C. Hansen: "The Modified TruncatedーSVD Method for Regularization in General Form." J.SIAM,in press. (1991)

[Publications] W. Unno: "Nonradial Oscillation of Stars(Second Edition)." University of Tokyo Press, 420 (1989)

[Publications] Y. Osaki: "Progress of Seismology of the Sun and Stars,Lecture Notes in Physics" SpringerーVerlag, 467 (1990)

尾崎洋二東京大学, 理学部, 教授 (30011547)