Standing fast magnetoacoustic kink waves of solar coronal loops with field-aligned flow
Abstract
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 A{max} = 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 A{max} and P are close to the observational data. A value of τ is about two times smaller than observed.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- September 2008
- DOI:
- 10.1051/0004-6361:200809873
- Bibcode:
- 2008A&A...488..757G
- Keywords:
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- magnetohydrodynamics (MHD);
- Sun: corona;
- Sun: oscillations