Acoustic wave propagation in the solar atmosphere. IV. Nonadiabatic wave excitation with frequency spectra.
Abstract
We study the response of the solar atmosphere to excitations by large amplitude acoustic waves with radiation damping now included. Monochromatic adiabatic waves, due to unbalanced heating, generate continuously rising chromospheric temperature plateaus in which the low frequency resonances quickly die out. All nonadiabatic calculations lead to stable mean chromospheric temperature distributions determined by shock dissipation and radiative cooling. For nonadiabatic monochromatic wave excitation, a critical frequency ν_cr_~1/25Hz is confirmed, which separates domains of different resonance behaviour. For waves of ν<ν_cr_, the resonances decay, while for waves of ν>ν_cr_ persistent resonance oscillations occur, which are perpetuated by shock merging. Excitation with acoustic frequency spectra produces distinct dynamical mean chromosphere models where the detailed temperature distributions depend on the shape of the assumed spectra. The stochasticity of the spectra and the ongoing shock merging lead to a persistent resonance behaviour of the atmosphere. The acoustic spectra show a distinct shape evolution with height such that at great height a pure 3min band becomes increasingly dominant. With our Eulerian code we did not find appreciable mass flows at the top boundary.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 August 1997
 arXiv:
 arXiv:astroph/9703106
 Bibcode:
 1997A&A...324..587T
 Keywords:

 HYDRODYNAMICS;
 SHOCK WAVES;
 WAVES;
 SUN: CHROMOSPHERE;
 SUN: OSCILLATIONS;
 Astrophysics
 EPrint:
 12 pages, 11 figures, accepted for publication in A &