MHD seismology of coronal loops using the period and damping of quasimode kink oscillations 

Inigo Arregui Submitted: 20061123 01:45
We combine the magnetohydrodynamic (MHD) theory of resonantly damped quasimode kink oscillations with observational estimates of the period and damping of
transverse coronal loop oscillations to extract information on physical parameters in oscillating loops.
A numerical study of the quasimode period and damping, in onedimensional fully nonuniform flux tubes, is used to obtain equilibrium models that reproduce the observed periods and damping rates. This scheme is applied to 11 loop oscillation events. When only the damping rate is used, the valid equilibrium models form a onedimensional solution curve in the twodimensional parameter space (density contrast, transverse inhomogeneity lengthscale). Lower limits to the transverse inhomogeneity are obtained in the limit of high contrast loops. When both the period and the damping rate are used, the equilibrium Alfvén speed (or Alfvén travel time) comes into play. The valid equilibrium
models then form a onedimensional solution curve, in the threedimensional parameter space (density contrast, transverse inhomogeneity lengthscale, Alfvén speed or Alfvén travel time). The projection of these solutions onto the Alfvén speed axis is found to be constrained to a rather limited interval. Upper limits to the internal Alfvén speed are derived for 9 of the 11 analysed events.
Authors: I. Arregui, J. Andries, T. Van Doorsselaere, M. Goossens, S. Poedts
Projects:

Publication Status: Published, A&A, Vol 463, 333338
Last Modified: 20070130 05:20


