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Enhanced emission of Alfvén waves from sunspots during proton flares

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Abstract

Thomas (1978) has shown that, if Alfvén waves exist in a sunspot umbra, they are normally reflected so strongly by the temperature minimum as to be essentially undetectable in the upper solar atmosphere. However, it is known that in many proton flares, chromospheric emission overlies the umbra of a sunspot, indicating that the transition region (TR) between chromosphere and corona in the umbral flux tube has moved down to lower altitudes. As a result of this lowering, umbral Alfvén waves have readier access to the corona: the coronal leakage depends exponentially on the altitude of the TR. We find that the Alfvén wave flux which leaks out of the umbra into the corona can exceed 107 ergs cm-2 s-1. A flux of this magnitude is expected to dissipate rapidly in the corona, thereby contributing to a positive feedback loop which ensures prolonged (∼1 hr) leakage of the umbral Alfvén waves into the corona. We propose that these Alfvén waves may contribute significantly to prolonged energization of proton flares in which umbral coverage occurs.

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References

  • Alfvén, H. and Fälthammer, C. G.: 1963, Cosmic Electrodynamics, Clarendon Press, Oxford, p. 86.

    Google Scholar 

  • Barbosa, D.: 1979, Astrophys. J. 233, 383.

    Google Scholar 

  • Beckers, J. M.: 1976, Astrophys. J. 203, 739.

    Google Scholar 

  • Beckers, J. M. and Schneeberger, T. J.: 1977, Astrophys. J. 215, 356.

    Google Scholar 

  • Belcher, J. W. and Davis, L.: 1971, J. Geophys. Res. 76, 3534.

    Google Scholar 

  • Brueckner, G. and Bartoe, J. D.: 1974, Solar Phys. 38, 133.

    Google Scholar 

  • Caroubalos, C.: 1964, Ann. Astrophys. 27, 333.

    Google Scholar 

  • Cheng, C. C., Doschek, G. A., and Feldman, U.: 1976, Astrophys. J. 210, 836.

    Google Scholar 

  • Chevalier, R. A. and Gardner, J.: 1974, Astrophys. J. 192, 457.

    Google Scholar 

  • De Jager, C.: 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development of Active Regions’, IAU Symp. 35, 480.

  • Dodson, H. W. and Hedeman, D. R.: 1970, Solar Phys. 13, 401.

    Google Scholar 

  • Eddy, J. A.: 1979, A New Sun: the Solar Results from Skylab, Washington, NASA SP-402, pp. 119–124.

  • Eichler, D.: 1979, Astrophys. J. 229, 413.

    Google Scholar 

  • Ellison, M. A., McKenna, S. M. P., and Reid, J. H.: 1961, Dunsink Obs. Publ., Vol. 1, No. 3.

  • Foukal, P. V., Huber, M. C. E., Noyes, R. W., Reeves, E. M., Schmahl, E. J., Timothy, J. G., Vernazza, J. G., and Withbroe, G. L.: 1974, Astrophys. J. Letters 193, L143.

    Google Scholar 

  • Frisch, U.: 1964, Ann. Astrophys. 27, 224.

    Google Scholar 

  • Hudson, H. S.: 1978, Solar Phys. 57, 237.

    Google Scholar 

  • Kahler, S. W., Hildner, E., and Van Hollobeke, M. A. L: 1978, Solar Phys. 57, 429.

    Google Scholar 

  • Kopp, R. A. and Pneuman, G. W.: 1976, Solar Phys. 50, 85.

    Google Scholar 

  • Machado, M. E. and Linsky, J. L.: 1975, Solar Phys. 42, 395 (ML).

    Google Scholar 

  • Machado, M. E. and Noyes, R. W.: 1978, Solar Phys. 59, 129.

    Google Scholar 

  • Melrose, D. B.: 1974, Solar Phys. 37, 353.

    Google Scholar 

  • Moore, R. L. and Fung, P. C. W.: 1972, Solar Phys. 23, 78.

    Google Scholar 

  • Moore, R. L. et al.: 1979, in P. A. Sturrock (ed.), Solar Flares, Colorado Assoc. Univ. Press, p. 401.

  • Moreton, G. and Severny, A.: 1968, Solar Phys. 3, 282.

    Google Scholar 

  • Mullan, D. J.: 1974, Astrophys. J. 187, 621.

    Google Scholar 

  • Mullan, D. J.: 1980, Astrophys. J. 237, 244.

    Google Scholar 

  • Noyes, R. W., Foukal, P. V., Huber, M. C. E., Reeves, E. J., Schmahl, E. J., Timothy, J. G., Vernazza, J. E., and Withbroe, G. L.: 1979, in S. R. Kane (ed.), ‘Solar Gamma-, X-, and EUV Radiation’, IAU Symp. 68, 3.

    Google Scholar 

  • Osterbrock, D. E.: 1961, Astrophys. J. 134, 347.

    Google Scholar 

  • Parker, E. N.: 1974, Solar Phys. 37, 127.

    Google Scholar 

  • Reinhard, R. and Wibberenz, G.: 1974, Solar Phys. 36, 473.

    Google Scholar 

  • Richter, A. K, and Olbers, D.: 1974, Astrophys. Space Sci. 26, 95.

    Google Scholar 

  • Sakurai, K.: 1965, Planetary Space Sci. 13, 745.

    Google Scholar 

  • Schatten, K. H. and Mullan, D. J.: 1977, J. Geophys. Res. 82, 5609 (SM).

    Google Scholar 

  • Shmeleva, O. P. and Syrovatskii, S. L.: 1973, Solar Phys. 33, 341.

    Google Scholar 

  • Spicer, D. S.: 1976, Naval Res. Lab. Report 8036.

  • Spitzer, L.: 1962, Physics of Fully Ionized Gases, Interscience, New York, p. 145.

    Google Scholar 

  • Sturrock, P. A.: 1979, in P. A. Sturrock (ed.), Solar Flares, Colorado Assoc. Univ. Press, p. 437.

  • Švestka, Z.: 1976, Solar Flares, D. Reidel Publ. Co., Dordrecht, Holland, pp. 21, 23.

    Google Scholar 

  • Švestka, Z. and Fritzová-Švestková, L.: 1974, Solar Phys. 36, 417.

    Google Scholar 

  • Thomas, J. H.: 1978, Astrophys. J. 225, 275.

    Google Scholar 

  • Thomas, J. H.: 1979, private communication.

  • Valdez, J. and Altschuler, M. A.: 1970, Solar Phys. 15, 446.

    Google Scholar 

  • Vernazza, J. E., Avrett, E. H., and Loeser, R.: 1973, Astrophys. J. 184, 605.

    Google Scholar 

  • Wentzel, D. G.: 1974, Solar Phys. 39, 129.

    Google Scholar 

  • Withbroe, G. L. and Noyes, R. W.: 1977, Ann. Rev. Astron. Astrophys. 15, 363.

    Google Scholar 

  • Yun, H. S. and Wyller, A. A.: 1972, Solar Phys. 27, 44.

    Google Scholar 

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  1. Bartol Research Foundation of The Franklin Institute, University of Delaware, 19711, Newark, Delaware, U.S.A.

    D. J. Mullan

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  1. D. J. Mullan
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Mullan, D.J. Enhanced emission of Alfvén waves from sunspots during proton flares. Sol Phys 70, 381–393 (1981). https://doi.org/10.1007/BF00151342

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  • DOI: https://doi.org/10.1007/BF00151342

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