Abstract
We consider the possibility that white light flares are due to heating of the photosphere by a flux of energetic ions and electrons impinging on it from above. Particles with energy in the range 10 MeV to 1 BeV release most of their energy to the ambient gas at about optical depth unity in the photosphere. This increase in energy produces a temperature perturbation of several hundred degrees in the layer and results in a re-radiation of the energy with a radiative relaxation time of several seconds. The consequences of this model are applied to a study of the great flare of May 23, 1967 and to the very fast event of August 11, 1954. Large numbers of very energetic electrons or protons must be produced in the first few minutes of the primary flare event if our interpretation (or one based on synchrotron emission) is correct.
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References
Allen, C. W.: 1955, Astrophysical Quantities, The Athlone Press, London, p. 140.
Bostrom, C. O., Kohl, J. W., Williams, D. J., and Arens, J. F.: 1969, World Data Center A, Report UAG-5,1968.
Bray, R. J. and Loughhead, R. E.: 1965, Sunspots, John Wiley & Sons, Inc., New York.
Carmichael, H.: 1964, AAS-NASA Symposium on The Physics of Solar Flares, NASA SP-50, p. 451.
Castelli, J. P., Aarons, J., and Michael, G. A.: 1968, Astrophys. J. 153, 267.
Cline, T. L., Holt, S. S., and Hones, E. W., Jr.: 1968, private communication.
Cline, T. L. and McDonald, F. B.: 1968, Solar Phys. 5, 507.
de Jager, C.: 1968, in Y. Öhman (ed.), ‘Mass Motions in Solar Flares and Related Phenomena’, Nobel Symp. 9, 171.
DeMastus, H. L. and Stover, R. R.: 1967, Publ. Astron. Soc. Pacific 79, 615.
Dodson, H. W. and Hedeman, E. R.: 1969, World Data Center A, Report UAG-5, 7.
Dubov, E. E.: 1964, AAS-NASA Symposium on The Physics of Solar Flares, NASA SP-50, p. 457.
Dulk, G. A.: 1969, World Data Center A, Report UAG-5, 29.
Evans, J. V. and Hagfors, T.: 1968, Radar Astronomy, McGraw-Hill Book Co., New York, pp. 88–98.
Fichtel, C. E. and McDonald, F. B.: 1967, Ann. Rev. Astron. Astrophys. 5, 351.
Kiepenheuer, K. O.: 1955, Trans. IAU IX, 670.
Korchak, A. A.: 1965, Geomagnetizm i Aeronomia 5, 467.
Krimigis, S. M.: 1965, J. Geophys. Res. 70, 2943.
Lanzerotti L. J.: 1969, World Data Center A, Report UAG-5, 56.
Lindgren, S. T.: 1968, Solar Phys. 5, 382.
McIntosh, P. S.: 1969, World Data Center A, Report UAG-5.
Mein, P.: 1966, Ann. Astrophys. 29, 153.
Miller, W. A.: 1955, Nature 175, 557.
Mustel, E. R.: 1955, Trans. IAU IX, 671.
Najita, K.: 1969, Doctoral Dissertation, University of Hawaii, Honolulu.
Najita, K. and Orrall, F. Q.: 1969, Bull. Am. Astron. Soc. 1, 254.
Sakurai, K.: 1967, Rep. Ionosphere Space Res. Japan 21, 213.
Schatzman, E.: 1963, The Solar Spectrum (ed. by C. de Jager), D. Reidel Publ. Co., Dordrecht, p, 313.
Scheuer, P. A. G.: 1968, Astrophys. J. Letters 151, 139.
Severny, A. B.: 1958, Soviet Phys. (Doklady) 3, 698.
Spiegel, E. A.: 1957, Astrophys. J. 126, 202.
Stein, W. A. and Ney, E. P.: 1963, J. Geophys. Res. 68, 65.
Sturodubtsev, S. V. and Romanov, A. M.: 1962, The Passage of Charged Particles Through Matter, A.E.C. Translation 6468.
Sturrock, P. A.: 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development of Solar Active Regions’, IAU Symp. 35, 471.
Švestka, Z.: 1966, Space Sci. Rev. 5, 388.
Sweet, P. A.: 1969, Ann. Rev. Astron. Astrophys. 7, 149.
Tallant, P. E.: 1968, private communication.
Van Allen, J. A.: 1968, Astrophys. J. 152, L85.
van de Hulst, H. C.: 1953, The Sun (ed. by G. P. Kuiper), The University of Chicago Press, Chapter 5.
Warwick, J. W.: 1964, AAS-NASA Symposium on the Physics of Solar Flares, NASA SP-50, p. 441.
Webber, W. R.: 1964, AAS-NASA Symposium on the Physics of Solar Flares, NASA SP-50, p. 215.
Westfold, K. C.: 1959, Astrophys. J. 130, 241.
Wild, J. P., Smerd, S. F., and Weiss, A. A.: 1963, Ann. Rev. Astron. Astrophys. 1, 291.
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After this paper had been submitted and accepted for publication we received from Dr. Švestka a copy of his paper, ‘The Phase of Particle Acceleration in the Flare Development’, which was then already in proof. (It appeared in Solar Phys. 13, 471.) A number of the arguments contained in our paper, which we had previously presented in abstract form (Najita and Orrall, 1969) and in part in a dissertation (Najita, 1969), are independently discussed by Dr. Švestka who was unaware of our earlier work. Although the ground covered by his and our paper touches in places we have left our paper as originally submitted and believe that this independent agreement supports the conclusions of both.
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Najita, K., Orrall, F.Q. White light events as photospheric flares. Sol Phys 15, 176–194 (1970). https://doi.org/10.1007/BF00149484
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DOI: https://doi.org/10.1007/BF00149484