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Wave Propagation in Sunspots

Published online by Cambridge University Press:  19 July 2016

S.S. Hasan
S.S. Hasan*
Affiliation:
Indian Institute of Astrophysics Bangalore 560034, India

Abstract

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In this paper, wave propagation in sunspot umbrae is analysed. The stratification in a typical umbra is approximated by a model atmosphere, extending vertically from a depth of a few thousand kilometres below the photosphere, to the transition region. No boundaries are imposed in the horizontal direction. It is assumed that this atmosphere is embedded in a uniform vertical field. Using a Rayleigh-Ritz variational technique, the normal mode frequencies of the umbra are calculated for different values of the horizontal wave number k. A theoretical diagnostic diagram is generated. An interesting feature of the solutions is the existence of ‘avoided crossings’, similar to those found in the study of global oscillations. The nature of the wave modes is examined by decomposing the eigenvectors into longitudinal and transverse components. In general, it is found that the character of a mode changes with height. For large k, modes with periods in the 2-3 min range, correspond to low order modes in the present calculation. Above the photosphere, they resemble slow waves.

Type
V. Photospheric Flux Tubes
Information
Symposium - International Astronomical Union , Volume 142: Basic Plasma Processes on the Sun , 1990 , pp. 189 - 191
Copyright
Copyright © Kluwer 1990 

References

Abdelatif, T.E., Lites, B.W., and Thomas, J.H. (1986), Astrophys. J. 311,1015.CrossRefGoogle Scholar
Antia, H. and Chitre, S.M. (1979), Solar Phys. 63,67.CrossRefGoogle Scholar
Balthasar, H. and Wiehr, E. (1984), Solar Phys. 94,99.CrossRefGoogle Scholar
Balthasar, H., Küveler, G.,and Wiehr, E. (1987), Solar Phys. 112, 39–48.CrossRefGoogle Scholar
Beckers, J.M. and Schulz, R.B. (1972), Solar Phys. 27,61.CrossRefGoogle Scholar
Bhatnagar, A., Livingston, W.C.,and Harvey, J.W. (1972), Solar Phys. 27,80.CrossRefGoogle Scholar
Gurman, J.B. and Leibacher, J.W. (1984), Astrophys. J. 283, 859.CrossRefGoogle Scholar
Gurman, J.B. (1987), Solar Phys. 108,61.CrossRefGoogle Scholar
Hasan, S.S. and Sobouti, Y. (1987), Mon. Not. R. astr. Soc. 228,427.CrossRefGoogle Scholar
Leroy, B. and Schwartz, S.J. (1982), Astron. Astrophys. 112,84.Google Scholar
Lites, B.W. and Thomas, J.H. (1985), Astrophys. J. 294,682.Google Scholar
Lites, B.W. (1986), Astrophys. J. 301,922.Google Scholar
Maltby, P., Avrett, E.H., Carlsson, M., Kjeldseth-Moe, O., Kurucz, R.L. and Loeser, R. (1986), Astrophys. J. 306,284.CrossRefGoogle Scholar
Scheuer, M.A. and Thomas, J.H. (1981), Solar Phys. 71,21.Google Scholar
Schröter, E.H. and Soltau, D. (1976), Astron. Astrophys. 449,463.Google Scholar
Soltau, D., Schröter, E.H.,and Wöhl, H. (1976), Astron. Astrophys. 50,367.Google Scholar
Thomas, J.H., Lites, B.W.,and Gurman, J.B. (1987), Astrophys. J. 312,457.CrossRefGoogle Scholar
Uchida, Y. and Sakurai, T. (1975), Publ. Astron. Soc. Japan 27,259.Google Scholar
Zhugzhda, Y.D. (1979), Sov. Astron. 23,42.Google Scholar
Zhugzhda, Y.D., Locan, V., and Staude, J. (1983) Solar Phys. 82, 369.CrossRefGoogle Scholar