On the generation of resonance oscillations in plane atmospheres.
Abstract
The paper deals with some selected properties of linear 1D resonance oscillations of plane stratified atmospheres. First, we study the response of a bounded isothermal atmosphere to a velocity pulse injected at the bottom of the atmosphere. For a family of pulses, we calculate the Lagrangian density perturbation at the bottom as this quantity indicates the response of the whole atmosphere. The analytical expressions give insight into details of the onset and the decay of the oscillation for finite times. We find that the principle asymptotic term governs the resonance oscillation only at large times. Further, we consider the influence of weak radiative damping on the oscillation. To study conditions for the existence of a resonance oscillation in nonisothermal atmospheres, we use transformations of the wave equation. By suitable transformations of the wave equation of a nonisothermal atmosphere to the wave equation of the homogeneous gas, we obtain some particular temperature stratifications which do not show the resonance oscillation. The solution of the wave equation of polytropic atmospheres with negative halfintegral index is discussed. By transformations of the wave equation to the wave equation of the isothermal atmosphere, we obtain temperature structures of atmospheric layers the dynamical behavior of which is equal to the behavior of the isothermal atmosphere. Further, we determine temperature stratifications which do not produce a real resonance oscillation, but significant distortions of sharp pulses.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 September 1995
 Bibcode:
 1995A&A...301..483S
 Keywords:

 HYDRODYNAMICS;
 SUN: ATMOSPHERE;
 SUN: OSCILLATIONS;
 STARS: ATMOSPHERES;
 STARS: OSCILLATIONS