Kink oscillations in the solar corona

Abstract

The solar coronal plasma is highly structured in the magnetic field, density and temperature. This plays a crucial role in the theory of MHD oscillations. In this study, we model a coronal loop to be made up of a cylindrical tube of constant cross-section. However, the magnetic field, the pressure and density are assumed to be different both inside and outside the tube. The tube admits modes such as sausage (symmetric), kink (asymmetric), surface and body modes. The dispersion relation of the modes for a cylindrical tube which is compressible, infinitely conducting with uniform flows inside the tube is derived. Limiting cases are discussed briefly. The phase speed of the kink mode can be used as a diagnostic for determining the magnetic field of the corona. For different values of the coronal parameters, the magnetic field varies from a few Gauss to 25 Gauss.