Nonlinear outcome of gravitational instability in cooling, gaseous disks

被引:817
作者
Gammie, CF [1 ]
机构
[1] Univ Illinois, Ctr Theoret Astrophys, Urbana, IL 61801 USA
关键词
accretion; accretion disks; galaxies : nuclei; solar system : formation;
D O I
10.1086/320631
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Thin, Keplerian accretion disks generically become gravitationally unstable at large radii. I investigate the nonlinear outcome of such instability in cool disks using razor-thin, focal, numerical models. Cooling, characterized by a constant cooling time tau (c), drives the instability. I show analytically that if the disk can reach a steady state in which heating by dissipation of turbulence balances cooling, then the dimensionless angular momentum flux density alpha = [(9/4)gamma(gamma - 1)Omega tau (c)](-1). Numerical experiments show that (1) if tau (c) greater than or similar to 3 Omega (-1) then the disk reaches a steady, gravitoturbulent state in which Q similar to 1 and cooling is balanced by heating due to dissipation of turbulence; (2) if tau (c) less than or similar to 3 Omega (-1), then the disk fragments, possibly forming planets or stars; (3) in a steady, gravitoturbulent state, surface density structures have a characteristic physical scale similar to 64G Sigma/Omega (2) that is independent of the size of the computational domain.
引用
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页码:174 / 183
页数:10
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