The role of linearly polarized transverse MHD waves in heating the solar coronal plasma

Abstract

ABSTRACT We derive a general dispersion relation for linearly polarized transverse magnetohydrodynamic (MHD) waves in an inhomogeneous, viscous, and resistive coronal plasma. We assume density structuring along the direction of polarization of the wave. In the linear regime and for an incompressible and homogeneous plasma, where the criterion of ignorable coordinates is satisfied, our solution corresponds to the customary Alfvén wave, which is basically dissipated by shear viscosity or resistivity. However, the assumption of density stratification along the direction of polarization of waves breaks down the criterion of ignorable coordinates, due to which transversal wave perturbations become compressible and, consequently, compressive viscosity turns out to be an important process. We find that for a typical coronal plasma with a magnetic field of 5 to 22 G, transverse body waves with a period of less than 10 s can dissipate energy on a time scale comparable to the coronal radiative time in their antisymmetric mode. Thus, it is possible that linearly polarized transverse wave perturbations dissipated by ion compressive viscosity maintain a hot coronal temperature.