Astron. Astrophys. 361, 1127-1142 (2000)

Influence of the solar atmosphere on the p-mode eigenoscillations

N.S. Dzhalilov ¹, J. Staude ² and K. Arlt <sup>2

1</sup> Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences, Troitsk City, Moscow Region, 142092, Russia (namig@izmiran.rssi.ru)
² Astrophysikalisches Institut Potsdam, Sonnenobservatorium Einsteinturm, 14473 Potsdam, Germany (jstaude, karlt@aip.de)

Received 12 April 2000 / Accepted 8 August 2000

Abstract

An asymptotic theory of global adiabatic p-modes is developed, taking into account the influence of the solar atmosphere. It is shown that waves of the whole frequency range  mHz may reach the chromosphere-corona transition region (CCTR) by means of a tunneling through the atmospheric barriers. The primary acoustic cavity inside the Sun becomes considerably extended by this way, leading to a change of frequencies: low frequencies are increased, while high frequencies are decreased. The transition from low p-mode frequencies to high peak frequencies mHz) is smooth.

The locations of the turning points are determined from the wave equation for . It is shown that the internal turning point of the acoustic cavity is strongly shifted toward the center of the Sun, while the upper turning point is shifted from the surface to CCTR. That means, the turning points cannot be located in the convective zone. A new complex integral dispersion relation for the eigenfrequencies is derived. The imaginary parts of the frequencies indicate a decay of the amplitudes, resulting from considerable energy losses by tunneling from the main cavity.

It is shown that waves with a decaying amplitude (complex frequency) may exist in a limited area only, penetration of linear p-modes to the corona is impossible. The CCTR acts as a free surface. We conclude that the p-modes may drive forced surface gravity waves at this surface.

Key words: hydrodynamics Sun: oscillations Sun: interior Sun: atmosphere

Send offprint requests to: J. Staude

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Contents

• 1. Introduction
  • 1.1. High frequency p-modes
  • 1.2. The chromospheric modes
• 2. Isothermal layers model
• 3. Basic equations
• 4. Where are the turning points?
  • 4.1. Upper turning point
  • 4.2. Lower turning point
• 5. Asymptotic solution
• 6. Boundary value problem
  • 6.1. Solar center
  • 6.2. Upper atmosphere
• 7. Eigenfrequencies of the radial oscillations
• 8. Discussion
• Acknowledgements
• Appendices
  • A: asymptotic solution around the upper turning point
• References

© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000
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