Volume 470, Number 1, July IV 2007
|353 - 357
|16 May 2007
Torsional oscillations of longitudinally inhomogeneous coronal loops
Georgian National Astrophysical Observatory (Abastumani Astrophysical Observatory), Kazbegi Ave. 2a, Tbilisi 0160, Georgia e-mail: firstname.lastname@example.org
2 Group of Astrophysics and Gravity Theory, Institute of Physics, UMCS, ul. Radziszewskiego 10, 20-031 Lublin, Poland
Accepted: 26 March 2007
Aims.We explore the effect of an inhomogeneous mass density field on frequencies and wave profiles of torsional Alfvén oscillations in solar coronal loops.
Methods.Dispersion relations for torsional oscillations are derived analytically in limits of weak and strong inhomogeneities. These analytical results are verified by numerical solutions, which are valid for a wide range of inhomogeneity strength.
Results.It is shown that the inhomogeneous mass density field leads to the reduction of a wave frequency of torsional oscillations, in comparison to that estimated from mass density at the loop apex. This frequency reduction results from the decrease of an average Alfvén speed as far as the inhomogeneous loop is denser at its footpoints. The derived dispersion relations and wave profiles are important for potential observations of torsional oscillations which result in periodic variations of spectral line widths.
Conclusions.Torsional oscillations offer an additional powerful tool for the development of coronal seismology.
Key words: magnetohydrodynamics (MHD) / Sun: corona / Sun: oscillations
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.