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Magnetic twist is thought to play an important role in coronal loops. Theeffects of magnetic twist on stable magnetohydrodynamic (MHD) waves is poorlyunderstood because they are seldom studied for relevant cases. The goal of thiswork is to study the fingerprints of magnetic twist on stable transverse kinkoscillations. We numerically calculated the eigenmodes of propagating andstanding MHD waves for a model of a loop with magnetic twist. The azimuthalcomponent of the magnetic field was assumed to be small in comparison to thelongitudinal component. We did not consider resonantly damped modes or kinkinstabilities in our analysis. For a nonconstant twist the frequencies of theMHD wave modes are split, which has important consequences for standing waves.This is different from the degenerated situation for equilibrium models withconstant twist, which are characterised by an azimuthal component of themagnetic field that linearly increases with the radial coordinate. In thepresence of twist standing kink solutions are characterised by a change inpolarisation of the transverse displacement along the tube. For weak twist, andin the thin tube approximation, the frequency of standing modes is unalteredand the tube oscillates at the kink speed of the corresponding straight tube.The change in polarisation is linearly proportional to the degree of twist.This has implications with regard to observations of kink modes, since thedetection of this variation in polarisation can be used as an indirect methodto estimate the twist in oscillating loops.

Transverse kink oscillations in the presence of twist