Astron. Astrophys. 324, 717-724 (1997)

Acoustic wave propagation in the solar atmosphere

V. Observations versus simulations

J. Theurer ¹, P. Ulmschneider ¹ and W. Kalkofen <sup>2

1</sup> Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstr. 15, D-69121 Heidelberg, Germany
² Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA

Received 28 January 1997 / Accepted 21 March 1997

Abstract

We study the evolution of spectra of acoustic waves that are generated in the convection zone and propagate upward into the photosphere, where we compare the simulated acoustic spectra with the spectrum observed in an Fe I line. Although there is no pronounced 3 min component in the spectra generated in the convection zone, there are dominant 3 min features in the theoretical spectra, in agreement with the observed spectrum. We interpret the occurrence of the 3 min features as the response of the solar atmosphere to the acoustic waves which shifts high frequency wave energy to low frequencies. We also find qualitative agreement for the acoustic power between the wave simulations and the observations.

Key words: hydrodynamics shock waves waves Sun: chromosphere Sun: oscillations

Send offprint requests to: P. Ulmschneider

Contents

• 1. Introduction
• 2. Method
  • 2.1. Initial wave spectrum
  • 2.2. Kolmogorov turbulent cascade, high frequencies
  • 2.3. Kolmogorov turbulent cascade, low frequencies
  • 2.4. Wave calculation, atmospheric model
  • 2.5. The observed frequency spectrum
  • 2.6. The modulation transfer function
• 3. Results
• 4. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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