Rossby wave instability of Keplerian accretion disks

被引:438
作者
Lovelace, RVE [1 ]
Li, H
Colgate, SA
Nelson, AF
机构
[1] Cornell Univ, Dept Astron, Ithaca, NY 14853 USA
[2] Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA
[3] Univ Arizona, Dept Phys, Tucson, AZ 85721 USA
基金
美国国家科学基金会;
关键词
accretion; accretion disks; hydrodynamics; instabilities; waves;
D O I
10.1086/306900
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We find a linear instability of nonaxisymmetric Rossby waves in a thin nonmagnetized Keplerian disk when there is a local maximum in the radial profile of a key function L(r) drop F(r)S-2/Gamma(r), where F-1 = (z) over cap . (V x v)/Sigma is the potential vorticity, S = P/Sigma(Gamma) is the entropy, Sigma is the surface mass density, P is the vertically integrated pressure, and r is the adiabatic index. We consider in detail the special case where there is a local maximum in the disk entropy profile S(r). This maximum acts to trap the waves in its vicinity if its height-to-width ratio max(S)/Delta r is larger than a threshold value. The pressure gradient derived from this entropy variation provides the restoring force for the wave growth. We show that the trapped waves act to transport angular momentum outward. A plausible way to produce an entropy variation is when an accretion disk is starting from negligible mass and temperature, therefore, negligible entropy. As mass accumulates by either tidal torquing, magnetic torquing, or Roche-lobe overflow, confinement of heat will lead to an entropy maximum at the outer boundary of the disk. Possible nonlinear developments from this instability include the formation of Rossby vortices and the formation of spiral shocks. What remains to be determined from hydrodynamic simulations is whether or not Rossby wave packets (or vortices) "hold together" as they propagate radially inward.
引用
收藏
页码:805 / 810
页数:6
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