On the stability of viscous accretion tori

With respect to the stability of accretion tori, the linear stability of vi scous compressible cylindrical annuli rotating in an external potential and having constant specific angular momentum distribution is investigated. A global stability analysis is performed, and the critical Reynolds numbers a s a function of the Mach number of the flow and the wavenumber of the pertu rbation are determined. Small-scale instabilities are stabilized below Reyn olds numbers of the order of 10(2)-10(3), while critical Reynolds numbers o f instabilities with azimuthal wavenumbers m = 1,2 are at most of the order of 10. We emphasize the relevance of critical Reynolds numbers for turbule nt Reynolds numbers in the configurations considered.