Slow magnetoacoustic standing waves in a curved solar coronal slab

¹ Department of Computer Sciences, The State School of Higher Education in Chełm, ul. Pocztowa 54, 22-100 Chełm, Poland e-mail: rogrodow@pwsz.chelm.pl
² Group of Astrophysics and Gravity Theory, UMCS, ul. Radziszewskiego 10, 20-031 Lublin, Poland
³ Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany

Received: 10 January 2008
Accepted: 1 October 2008

Abstract

Aims. We consider a model of a two-dimensional solar coronal arcade to explore the effects of a curved magnetic field topology on excitation and attenuation of slow magnetoacoustic standing waves.

Methods. The time-dependent ideal magnetohydrodynamic equations are solved numerically to find the spatial and temporal signatures of these waves.

Results. A pulse in gas pressure initially launched at a loop footpoint excites the fundamental mode of slow magnetoacoustic standing waves. The typical excitation time of such a wave mode is 2.5 wave periods, with a similar attenuation timescale. These values are remarkably similar to those recovered from observations by SOHO/SUMER in an Fe XIX line.

Conclusions. Slow magnetoacoustic standing waves are excited and attenuated more efficiently in curved magnetic field lines than in a straight magnetic slab topology. The waves supported by the magnetic arcade are in far closer agreement with observations.