## MHD eigenmodes in a semi-infinite structured solar atmosphere
Centrum voor Plasma Astrofysica, K.U. Leuven, Celestijnenlaan 200 B, B-3001 Heverlee, Belgium
Linear eigenmodes are determined for the solar atmosphere in the presence of a gravitational field and a magnetic field. The atmosphere consists of a horizontal nonuniform chromosphere and a semi-infinite nonuniform corona. It is bounded from below by a heavy and immovable photosphere. Inhomogeneity is confined to the vertical direction. The gravitational acceleration is constant and the equilibrium magnetic field is horizontal. The equilibrium temperature increases linearly with height in the chromosphere and is constant in the corona. The equilibrium magnetic field is constant in the chromosphere and it decreases with height in the corona in such a way that the Alfvén speed is constant there. The results show that there are two sets of eigenmodes which can be
viewed as The modes can become damped quasimodes with complex frequencies arising from the resonant coupling of eigenmodes to the local MHD continua in the nonuniform chromospheric layer.
* On leave from Eötvös L. University, H-1083 Budapest, Hungary
## Contents- 1. Introduction
- 2. The model of a semi-infinite atmosphere
- 3. Basic equations and assumptions
- 4. Solutions of MHD equations
- 4.1. The corona:
- 4.2. The chromosphere:
- 5. Eigenvalue solutions
- 6. Numerical results
- 7. Conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998 Online publication: March 23, 1998 |