Rotational viscosity in linear irreversible thermodynamics and its application to neutron stars

A generalized analysis of the local entropy production of a simple fluid is used to show that, if intrinsic angular momentum is taken into account, rotational viscosity must arise in the linear non-equilibrium regime. As a consequence, the stress tensor of dense rotating matter, such as the one present in neutron Stars, posseses a significant non-vanishing antisymmetrical part. A simple argument suggests that, due to the extreme magnetic fields present in neutron stars, the relaxation time associated to rotational viscosity is large (similar to 10(21) s). The formalism leads to generalized Navier-Stokes equations useful in neutron star physics which involve vorticity in the linear regime.