The Influence of the Chromosphere and Corona on the Solar Atmospheric Oscillations
Abstract
The influence of the chromosphere and corona on the solar atmospheric oscillations is examined by solving the equations of linear non- adiabatic nonradial oscillations for a realistic solar atmosphere-envelope model including the chromosphere and corona. Some of wave energy leaks to the corona by running waves for acoustic modes with small horizontal wavenumbers. It is, however, found that the energy leakage is not serious for the stability of most modes. It is shown that there exists an acoustic mode trapped in the chromosphere besides the ordinary ones trapped in the convection zone in the range of horizontal wavenumber kx0. .0 . Its angular frequency a is about 0.027 s ', being almost independent of the horizontal wavenumber, and this mode is always vibrationally stable. In regions on the diagnostic (kx, a)- diagram where a curve showing the mode trapped in the chromosphere crosses the curves showing several harmonic modes trapped in the convection zone, resonance occurs between these two modes resulting in the mixing of eigenfunctions. In the diagnostic (kx, a) -diagram, unstable eigenmodes form a series of many, nearly parallel ridges (one for each radial order), which is in good agreement with recent observations of the five-minute oscillation by Deubner (1975). Key words: Chromosphere and corona; Five-minute oscillation; Overstability of acoustic modes.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- 1977
- Bibcode:
- 1977PASJ...29..221A