Energy leakage as an attenuation mechanism for vertical kink oscillations in solar coronal wave guides

¹ Group of Astrophysics and Gravity Theory, Institute of Physics, UMCS, ul. Radziszewskiego 10, 20-031 Lublin, Poland e-mail: mselwa@kft.umcs.lublin.pl
² Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
³ Department of Physics, Montana State University, Bozeman, MT 59717-3840, USA

Received: 1 March 2006
Accepted: 8 October 2006

Abstract

Aims.We study wave leakage as a possible attenuation mechanism of coronal loop oscillations in the ideal MHD regime.

Methods.We consider impulsively generated oscillations in solar coronal magnetic wave guides such as a straight slab and a curved arcade loop. The two-dimensional numerical model we implement includes the effects of nonlinearity and line curvature on attenuation of fast magnetosonic kink waves.

Results.We show that these waves are more strongly attenuated in the arcade loop than in the slab and provide evidence that the curvature of magnetic field lines results in excess energy leakage. For parameters appropriate for a coronal loop the kink oscillation is too efficiently attenuated by energy leakage, suggesting that in the solar atmosphere wave leakage must be reduced compared to our simulations. We conclude that energy leakage is an efficient source of attenuation of coronal loop oscillations.