Gravitational instability of nonuniformly rotating and magnetized viscoelastic fluid with dissipative effects.

In this paper, the effect of dissipative energy arising from bulk-viscosity on the collapse of a self-gravitating viscoelastic medium permeated with a nonuniform magnetic field and rotation is analyzed using the standard Jeans mechanism. A local solution of the system of nondimensional linearized perturbation equations, having variable coefficients, is obtained using the normal modes analysis method. The Jeans instability criteria are derived from the characteristic equation (valid under the kinetic and hydrodynamic limits) for parallel and perpendicular wave propagation, modified due to bulk viscosity and Alfvén wave velocity. From the calculated critical values of Jeans wavenumber, it is found that the bulk-viscosity and magnetic field have stabilizing influence on the onset of gravitational instability for each mode of wave propagation. It is observed that the nonuniform rotation does not affect the instability criterion, however, the rotation strongly suppresses the growth rate of the Jeans instability in both the hydrodynamic and kinetic limits. Also, a comparison of the impact of various rotational and magnetic field orientations on the growth rate in viscoelastic fluid is also presented. From the analysis, it is also observed that the presence of dissipative energy reduces the growth rate, in both modes of wave propagation. [ABSTRACT FROM AUTHOR]