Alpha-viscosity effects in slender tori


Horak, Jin; Abramowicz, Marek A.; Levin, Lina; Slapak, Rikard; Straub, Odele


We explore effects of the Shakura–Sunyaev ˛-viscosity on the dynamics and oscillations of slender tori. We start with a slow secular evolution of the torus. We show that the angular-momentum profile approaches the Keplerian one on a timescale longer than a dynamical one by a factor on the order of 1=˛. We then focus our attention on the oscillations of the torus. We discuss the effects of various angular-momentum distributions. Using a perturbation theory, we have found a rather general result that the high-order acoustic modes are damped by the viscosity, while the high-order inertial modes are enhanced. We calculate viscous growth rates for the lowest-order modes, and show that already the lowest-order inertial mode is unstable for less-steep angular-momentum profiles, or very close to the central gravitating object.

Publication year


Publication type

Journal article


Publications of the Astronomical Society of Japan, Vol. 64, no. 4 (Aug 2012), p. 76




Astronomical Society of Japan


Copyright © 2012. Astronomical Society of Japan.