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Torsional alfvén waves in small scale current threads of the solar corona

dc.contributor.authorCopil, P.
dc.contributor.authorVoitenko, Y.
dc.contributor.authorGoossens, M.
dc.date2010
dc.date.accessioned2016-03-30T12:01:16Z
dc.date.available2016-03-30T12:01:16Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/3162
dc.descriptionContext. The magnetic field structuring in the solar corona occurs on large scales (loops and funnels), but also on small scales. For instance, coronal loops are made up of thin strands with different densities and magnetic fields across the loop. Aims. We consider a thin current thread and model it as a magnetic flux tube with twisted magnetic field inside the tube and straight field outside. We prove the existence of trapped Alfvén modes in twisted magnetic flux tubes (current threads) and we calculate the wave profile in the radial direction for two different magnetic twist models. Methods. We used the Hall MHD equations that we linearized in order to derive and solve the eigenmode equation for the torsional Alfvén waves. Results. We show that the trapped Alfv én eigenmodes do exist and are localized in thin current threads where the magnetic field is twisted. The wave spectrum is discrete in phase velocity, and the number of modes is finite and depends on the amount of the magnetic field twist. The phase speeds of the modes are between the minimum of the Alfvén speed in the interior and the exterior Alfén speed. Conclusions. Torsional Alfvén waves can be guided by thin twisted magnetic flux-tubes (current threads) in the solar corona. We suggest that the current threads guiding torsional Alfvén waves, are subject to enhanced plasma heating due to wave dissipation.
dc.languageeng
dc.titleTorsional alfvén waves in small scale current threads of the solar corona
dc.typeArticle
dc.subject.frascatiPhysical sciences
dc.audienceScientific
dc.subject.freeCoronal loops
dc.subject.freeEigen modes
dc.subject.freeHall MHD
dc.subject.freeIn-phase
dc.subject.freeMagnetic flux tube
dc.subject.freeMagnetohydrodynamics (MHD)
dc.subject.freeMagnetohydrodynamics suns
dc.subject.freeN-waves
dc.subject.freePhase speed
dc.subject.freeRadial direction
dc.subject.freeSmall scale
dc.subject.freeSolar corona
dc.subject.freeSun: corona
dc.subject.freeWave dissipation
dc.subject.freeWave profiles
dc.subject.freeWave spectra
dc.subject.freeLiquefaction of gases
dc.subject.freeMagnetic flux
dc.subject.freeMagnetic structure
dc.subject.freeMagnetohydrodynamics
dc.subject.freeSolar radiation
dc.subject.freeSun
dc.subject.freeTubes (components)
dc.subject.freeMagnetic fields
dc.source.titleAstronomy and Astrophysics
dc.source.volume510
dc.source.issue1
dc.source.pageA17
Orfeo.peerreviewedYes
dc.identifier.doi10.1051/0004-6361/200912784
dc.identifier.scopus2-s2.0-77149130176


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