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Variations of microwave emission from solar active regions

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Abstract

Based on observational data obtained with the RT-22 Crimean Astrophysical Observatory radio telescope at frequencies of 8.6 and 15.4 GHz, we investigate the quasi-periodic variations of microwave emission from solar active regions with periods T p<10 min. As follows from our wavelet analysis, the oscillations with periods of 3–5 min and 10–40 s have the largest amplitudes in the dynamic power spectra, while there are virtually no oscillations with T p<10 s. Our analysis shows that acoustic modes with T p≲1 min strongly dissipate in the lower solar corona due to thermal conduction losses. The oscillations with T p=10–40 s are associated with Alfvén disturbances. We analyze the influence of acoustic and Alfvén oscillations on the thermal mechanisms of microwave emission in terms of the homogeneous model. We discuss the probable coronal heating sources.

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Authors and Affiliations

  1. Pulkovo Astronomical Observatory, Russian Academy of Sciences, Pulkovskoe shosse 65, St. Petersburg, 196140, Russia

    G. B. Gelfreikh, Yu. G. Kopylova & Yu. A. Nagovitsyn

  2. Crimean Astrophysical Observatory, p/o Nauchnyi, Crimea, 334413, Ukraine

    Yu. T. Tsap & L. I. Tsvetkov

  3. Kalmyk State University, Elista, Russia

    T. B. Goldvarg

Authors
  1. G. B. Gelfreikh
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  2. Yu. T. Tsap
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  3. Yu. G. Kopylova
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  4. T. B. Goldvarg
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  5. Yu. A. Nagovitsyn
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  6. L. I. Tsvetkov
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__________

Translated from Pis'ma v Astronomicheski\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) Zhurnal, Vol. 30, No. 7, 2004, pp. 540–547.

Original Russian Text Copyright © 2004 by Gelfreikh, Tsap, Kopylova, Goldvarg, Nagovitsyn, Tsvetkov.

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Gelfreikh, G.B., Tsap, Y.T., Kopylova, Y.G. et al. Variations of microwave emission from solar active regions. Astron. Lett. 30, 489–495 (2004). https://doi.org/10.1134/1.1774401

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  • DOI: https://doi.org/10.1134/1.1774401

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