Standing fast magnetoacoustic kink waves of solar coronal loops with field-aligned flow
Group of Astrophysics and Gravity Theory, Institute of Physics, UMCS, ul. Radziszewskiego 10, 20-031 Lublin, Poland e-mail: firstname.lastname@example.org
2 The Catholic University of America, NASA Goddard Space Flight Centre, Code 671, Greenbelt, MD 20771, USA
Accepted: 6 June 2008
Aims. We refer to the recent observational data of Hinode, which detected weakly-attenuated coronal loop oscillations in the presence of background flow (Ofman & Wang 2008, A&A, 482, L9). Vertical loop oscillations that lasted for three wave periods were reported with a wave period P = 113 ± 2 s, attenuation time τ = 560 ± 260 s, and wave amplitude = 0.67 ± 0.12 Mm. Ofman & Wang (2008) estimated the flow speed within the range of 74–123 km s-1. We consider impulsively generated standing fast magnetoacoustic kink waves of a straight solar coronal slab with field-aligned internal flow. We aim to determine the influence of such flow on the spatial and temporal signatures of these waves.
Methods. The time-dependent, ideal magnetohydrodynamic equations are solved numerically.
Results. The numerical results show that as a result of wave scattering on inhomogeneous flow kink waves experience stronger attenuation than for a still plasma, while P remains weakly altered by this flow. Numerically evaluated values of and P are close to the observational data. A value of is about two times smaller than observed.
Key words: magnetohydrodynamics (MHD) / Sun: corona / Sun: oscillations
© ESO, 2008