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Astron. Astrophys. 351, 359-367 (1999)

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Propagation of nonlinear longitudinal-transverse waves along magnetic flux tubes in the solar atmosphere

III. Modified equation of motion

A. Osin 1,3, S. Volin 2,3 and P. Ulmschneider 3

1 Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences, 142092 Troitsk, Moscow Region, Russia
2 Institute for Nuclear Research, Russian Academy of Sciences, 142092 Troitsk, Moscow Region, Russia
3 Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstrasse 15, 69121 Heidelberg, Germany

Received 4 July 1996 / Accepted 18 August 1999


In this series of papers the time-dependent propagation of nonlinear longitudinal-transverse waves in thin vertical magnetic flux tubes embedded in the solar atmosphere is investigated numerically using the (one-dimensional) thin tube approximation. As in the last decade the particular form of the backreaction term in the transverse equation of motion has been under considerable dispute we investigate this issue once again and suggest a new expression for the backreaction term in the local approximation. This new expression intends to avoid criticisms leveled at the previous terms. In the present paper we numerically compare the actual effects these different terms produce in a number of cases including the situations where the reported discrepancies are prominent. We find that noticeable discrepancies between the various proposed backreaction terms occur only, when strong longitudinal fluid flows are present simultaneously with the swaying of the tube and that for weak flows these discrepancies disappear. If only weak longitudinal flows occur it thus appears that the particular choice of the backreaction term is not important.

Key words: Magnetohydrodynamics (MHD) – methods: numerical – Sun: magnetic fields – Sun: chromosphere – Sun: corona

Send offprint requests to: P. Ulmschneider

Correspondence to: ulm@ita.uni-heidelberg.de

© European Southern Observatory (ESO) 1999

Online publication: November 2, 1999