Vl. Polyachenko et Ev. Polyachenko, STABILITY OF SELF-GRAVITATING ASTROPHYSICAL DISKS, Journal of experimental and theoretical physics, 85(3), 1997, pp. 417-429
Criteria which guarantee the stability of self-gravitating gaseous and
stellar disks toward any localized small perturbations are obtained.
These criteria are formulated as inequalities of the form Q > Q(c) (se
parately for gas and stars). The latter should be satisfied by the ''s
tability parameter'' Q, which is equal, by definition, to unity on the
stability boundary of radial perturbations. The critical value of the
stability parameter Q(c) is appreciably greater than (although of the
order of) unity, attesting to the great instability of nonaxially sym
metric perturbations. It is shown that the stability criterion derived
for gaseous disks is valid for disks rotating within a spheroidal com
ponent (as in spiral galaxies) or in the field of a central mass (plan
etary rings and accretion disks). Stellar disks are stabilized with si
gnificantly greater difficulty. This is attributable mainly to the ani
sotropy of the velocity distribution inherent to them, which is favora
ble for instability. (C) 1997 American Institute of Physics.