SECULAR INSTABILITY IN QUASI-VISCOUS DISK ACCRETION

摘要

A first-order correction in the α-viscosity parameter of Shakura & Sunyaev has been introduced in the standard inviscid and thin accretion disk. A linearized time-dependent perturbative study of the stationary solutions of this "quasi-viscous" disk reveals the development of a secular instability on large spatial scales. This qualitative feature is equally manifest for two different types of perturbative treatment: a standing wave on subsonic scales, as well as a radially propagating wave. The stability of the flow is restored when the viscosity disappears.