Volume 430, Number 3, February II 2005
|Page(s)||L65 - L68|
|Published online||26 January 2005|
Letter to the Editor
Transverse waves in a post-flare supra-arcade
Department of Physics, University of Warwick, Coventry CV4 7AL, UK e-mail: Erwin.Verwichte@warwick.ac.uk
Accepted: 10 December 2004
Observations of propagating transverse waves in an open magnetic field structure with the Transition Region And Coronal Explorer (TRACE) are presented. Waves associated with dark tadpole-like sunward moving structures in the post-flare supra-arcade of NOAA active region 9906 on the 21 of April 2002 are analysed. They are seen as quasi-periodic transverse displacements of the dark tadpole tails, with periods in the range of 90–220 s. Their phase speeds and displacement amplitudes decrease as they propagate sunwards. At heights of 90 and 60 Mm above the post-flare loop footpoints the phase speeds are in the ranges 200–700 km s-1 and 90–200 km s-1 respectively. Furthermore, for consecutive tadpoles the phase speeds decrease and periods increase as a function of time. The waves are interpreted as propagating fast magnetoacoustic kink waves guided by a vertical, evolving, open structure.
Key words: Sun: oscillations / magnetohydrodynamics (MHD)
© ESO, 2005
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