The effect of curvature on quasi-modes in coronal loops*
Centre for Plasma Astrophysics, KU Leuven, Belgium e-mail: email@example.com
Accepted: 3 June 2004
This paper studies quasi-mode oscillations in models of coronal loops that include longitudinal curvature. Using a toroidal coordinate system to incorporate curvature in a basic coronal loop model, the linearized ideal MHD equations are solved for the plasma-. As a result of the curvature, quasi-modes with different poloidal wave numbers are coupled resulting in modifications of the frequencies. However, for small curvature, only the coupling of quasi-modes with a neighbouring poloidal wave number remains in first order. In addition, the quasi-mode frequencies are unchanged up to first order in the curvature. The imaginary part of the frequency, however, does change in first order, and quasi-modes are slightly more damped in realistically curved coronal loop configurations.
Key words: magnetohydrodynamics (MHD) / plasmas / Sun: corona / Sun: oscillations
© ESO, 2004