Abstract
We propose that when all sources on the solar disc are taken into account, the S component at 10.7 cm wavelength is dominated by thermal free-free (bremsstrahlung) emission. It is not produced only in the vicinity of sunspots; more than 60% of the total flux may be due to a widely-distributed emission associated with the hot complexes of activity. Using a model for the solar atmosphere based upon an assumption of weak (or vertical) magnetic fields, the spectrum of the S-component is calculated and its sensitivity to changes in the model parameters investigated. Variation of the thicknesses of the chromosphere, transition region and mixed zone cause only small changes in the S-component spectrum; there is a much stronger dependence upon the plasma density, particularly at the base of the corona. The behaviour of the S-component at 10.7 cm wavelength is examined in more detail. We find that the largest contribution to the 10.7 cm flux originates in the low corona, that structural changes affect it only slightly, but that it is strongly density-related. This dependence upon few quantities, together with its relative localization in the low corona, contributes to the usefulness of the 10.7 cm flux as an index of solar activity.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Akhmedov, Sh. B., Borovik, V. N., Gelfreikh, G. B., Bogod, V. M., Korzhavin, A. N., Petrov, Z. E., Dikij, V. N., Lang, K. R., Willson, R. F.: 1986, Astrophys. J. 301, 460.
Alfvén, H.: 1981, Cosmic Plasma, Astrophysics and Space Science Library, D. Reidel Publ. Co., Dordrecht, Holland.
Bossy, L.: 1983, Planetary Space Sci. 31, 977.
Chapman, D. C. and Neupert, W.: 1974, J. Geophys. Res. 79, 4138.
Chiuderi Drago, F., Bandiera, R., Falciani, R., Antonucci, E., Lang, K. R., Willson, R. F., Shibasaki, K., and Slottje, C.: 1982, Solar Phys. 80, 71.
Covington, A. E.: 1947, Nature 159, 405.
Covington, A. E.: 1948, Proc. I.R.E. 36, 454.
Denisse, J.-F.: 1948, Ph.D. Thesis, Université de Paris.
Donnelly, R. F., Heath, D. F., Lean, J. L., and Rottman, G. L.: 1983, J. Geophys. Res. 88, 9883.
Erskine, F. T. and Kundu, M. R.: 1982, Solar Phys. 76, 221.
Felli, M., Lang, K. R., and Willson, R. F.: 1981, Astrophys. J. 247, 325.
Gaizauskas, V. and Tapping, K. F.: 1988, Astrophys. J. 325, 912.
Gaizauskas, V., Harvey, K. L., Harvey, J. W., and Zwaan, C.: 1983, Astrophys. J. 265, 1056.
Gary, D. E. and Hurford, G.: 1987, Astrophys. J. 317, 522.
Hedin, A. E.: 1984, J. Geophys. Res. 89, 9828.
Kakinuma, T. and Swarup, G.: 1962, Astrophys. J. 136, 975.
Krüger, A.: 1979, Introduction to Solar Radio Astronomy and Radio Physics, D. Reidel Publ. Co., Dordrecht, Holland.
Krüger, A., Hildebrandt, J., and Fürstenberg, F.: 1985, Astron. Astrophys. 143, 72.
Kundu, M.: 1965, Solar Radio Astronomy, John Wiley Publishers, New York.
Lang, K. R., Willson, R. F., and Gaizauskas, V.: 1983, Astrophys. J. 267, 455.
Lantos, P.: 1968, Ann. Astrophys. 31, 105.
Lean, J.: 1987, J. Geophys. Res. 91, 839.
Nicolet, M. and Bossy, L.: 1985, Planetary Space Sci. 33, 507.
Oster, L.: 1983, J. Geophys. Res. 88, 1953.
Oster, L.: 1983, J. Geophys. Res. 88, 9037.
Schmahl, E. J., Kundu, M. R., Strong, K. T., Bentley, R. D., Smith, J. B. Jr., and Krall, K. R.: 1982, Solar Phys. 80, 233.
Tapping, K. F.: 1987a, J. Geophys. Res. 92, 829.
Tapping, K. F.: 1987b, in Foukal (ed.), Proceedings of Workshop on Solar Radiative Output Variation, National Center for Atmospheric Research, Boulder, Colorado.
Waldmeier, M. and Müller, H.: 1950, Z. Astrophys. 27, 58.
Webb, D. F., Davis, J. M., Kundu, M. R., and Velusamy, T.: 1983, Solar Phys. 85, 267.
Zheleznyakov, V. V.: 1962, Soviet Astron. AJ 6, No. 1, 3.
Author information
Authors and Affiliations
Additional information
Summer Student Worker, 1988.
Rights and permissions
About this article
Cite this article
Tapping, K.F., DeTracey, B. The origin of the 10.7 cm flux. Sol Phys 127, 321–332 (1990). https://doi.org/10.1007/BF00152171
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00152171