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The origin of cutoff frequencies for torsional tube waves propagating in the solar atmosphere
Author(s) -
Hammer R.,
Musielak Z.E.,
Routh S.
Publication year - 2010
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.201011380
Subject(s) - physics , cutoff , chromosphere , atmosphere (unit) , cutoff frequency , vortex , mechanics , solar atmosphere , astrophysics , momentum (technical analysis) , flux (metallurgy) , classical mechanics , computational physics , astronomy , optics , meteorology , magnetic field , spectral line , finance , quantum mechanics , economics , metallurgy , materials science
Torsional waves supported by magnetic flux tubes have long been thought to bear a high potential for supplying energy and momentum to the upper solar atmosphere, thereby contributing to its heating and to the driving of dynamic events like spicules. This hope rested on the belief that their propagation is not impeded by cutoff restrictions, unlike longitudinal and kink waves. We point out that this applies only to thin, isothermal tubes. When they widen in the chromosphere, and as a result of temperature gradients, cutoff restrictions arise. We compare them to recent observational reports of such waves and of vortex motions and find that their long period components are already affected by cutoff restrictions. An observational strategy is proposed that should permit the derivation of better information on vortex flows from off‐center observations with next generation telescopes (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)