Wave motions in magnetic interstellar medium

Abstract

This communication considers the continuum approach modelling of large-scale dynamics of a nonconducting interstellar medium capable of sustaining long-ranged filamentary agglomeration of tiny superparamagnetic grains suspended in a dense molecular cloud. The filamentary ordering of permanently magnetized grains, oriented in the direction of the regular galactic field threading the cloud, is thought of as an effect of soft magnetic solidification of a nonconducting gas-dust substance imparting to the interstellar material the mechanical features of single-axis magnetoelastic insulators. With this physical picture in mind, we set up macroscopic equations to study the dissipative-free motions of superparamagnetic gas-dust nonionized matter in terms of continuum mechanics magnetoelastic materials. Particular attention is given to oscillatory behavior in the regime of strong magnetization-flow coupling. The most remarkable inference of this model is that nonconducting magnetically polarized interstellar medium can transmit perturbations by transverse waves of magnetization which can be regarded as a counterpart of Alfvén waves generic to cosmic dusty plasma. © 2000 Kluwer Academic/Plenum Publishers.