Solar Physics

, Volume 31, Issue 2, pp 389–400 | Cite as

The Hα flare as a secondary product of a coronal instability

  • Z. Švestka
Article
Received:

Abstract

The assumption that the flare originates in the corona or transition layer, is confronted with the known properties of chromospheric flares. It is concluded that the basic mode of the energy transport into chromosphere is heat conduction. Only in some flares non-thermal particles contribute to the brightening in lower atmospheric layers: electrons with energy close to 100 keV produce chromospheric bright patches, and protons above 20 MeV cause the photospheric enhancements. The particle-produced brightenings are superposed on the basic quasi-thermal flare and involve only small areas as compared with the extensive regions heated through conduction.

The most probable height of the flare origin appears to be close to the transition layer, between some 4000 and 7000 km above the photosphere. The non-thermal acceleration (when present) occurs probably higher than where the flare originates. There is no obvious reason why the high electron density in chromospheric flares could not be explained as simply due to increased ionization in the existing plasma, without any flare-induced mass condensations.

Though there are several facts supporting the flare origin in the corona (or transition layer), one cannot exclude the alternative that the flare instability involves simultaneously a wide (and in different cases different) range of altitudes. Energy considerations give some support to such a supposition.

Keywords

Flare Transition Layer High Electron Obvious Reason Secondary Product 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in to check access.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Biswas, S. and Radhakrishnan, B.: 1973, Solar Phys. 28, 211.Google Scholar
  2. Brown, J. C.: 1971, Solar Phys. 18, 489.Google Scholar
  3. Brown, J. C.: 1972, Solar Phys. 25, 158.Google Scholar
  4. Brown, J. C.: 1973, Solar Phys., 31, 143.Google Scholar
  5. Cheng, Chung-Chieh: 1972, Solar Phys. 22, 178.Google Scholar
  6. Chupp, E. L., Forrest, D. J., Higbie, P. R., Suri, A. N., Tsai, C., and Dunphy, P. B.: 1972, Nature 241, 333.Google Scholar
  7. Cox, D. P. and Tucker, W. H.: 1969, Astrophys. J. 157, 1157.Google Scholar
  8. Culhane, J. L., Vesecky, J. F., and Phillips, K. J. H.: 1970, Solar Phys. 15, 394.Google Scholar
  9. De Feiter, L. D.: 1966, Rech. Astron. Obs. Utrecht, No. 18 (2).Google Scholar
  10. De Jager, C.: 1967, Solar Phys. 2, 327.Google Scholar
  11. De Mastus, H. L. and Stover, R. R.: 1967, Publ. Astron. Soc. Pacific 79, 615.Google Scholar
  12. Dodson, H. W. and Hedeman, E. R.: 1970, Solar Phys. 13, 401.Google Scholar
  13. Elliot, H.: 1969, in C. de Jager and Z. Švestka (eds.), ‘Solar Flares and Space Research’, Caspar Symp., p. 356.Google Scholar
  14. Énomé, S., Kakinuma, T., and Tanaka, H.: 1969, Solar Phys. 6, 468.Google Scholar
  15. Gingerich, G., Noyes, R. W., Kalkofen, W., and Cuny, Y.: 1971, Solar Phys. 18, 347.Google Scholar
  16. Hudson, H. S.: 1972, Solar Phys. 24, 414.Google Scholar
  17. Hudson, H. S. and Ohki, K.: 1972, Solar Phys. 23, 155.Google Scholar
  18. Hyder, C. L.: 1967, Solar Phys. 2, 49 and 267.Google Scholar
  19. Kahler, S. W. and Kreplin, R. W.: 1970, Solar Phys. 14, 372.Google Scholar
  20. Kandel, R. S., Papagiannis, M. D., and Strauss, F. M.: 1971, Solar Phys. 21, 176.Google Scholar
  21. Kane, S. R.: 1969, Astrophys. J. Letters 157, L. 139.Google Scholar
  22. Kane, S. R. and Anderson, K. A.: 1970, Astrophys. J. 162, 1003.Google Scholar
  23. Kane, S. R., Kahler, S. W., and Kurfess, J. D.: 1972, Solar Phys. 25, 418.Google Scholar
  24. Kelly, P. T. and Rense, W. A.: 1972, Solar Phys. 26, 431.Google Scholar
  25. Korchak, A. A.: 1972, Paper presented at the XIV Meeting of COSPAR, Madrid.Google Scholar
  26. Lin, R. P. and Hudson, H. S.: 1971, Solar Phys. 17, 412.Google Scholar
  27. McIntosh, P. S. and Donnelly, R. F.: 1972, Solar Phys. 23, 444.Google Scholar
  28. Moore, R. L. and Fung, P. C. W.: 1972, Solar Phys. 23, 78.Google Scholar
  29. Moreton, G. E. and Severny, A. B.: 1968, Solar Phys. 3, 282.Google Scholar
  30. Najita, K. and Orrall, F. Q.: 1970, Solar Phys. 15, 176.Google Scholar
  31. Nakagawa, Y., Wu, S. T., and Han, S. M.: 1973, Solar Phys., 30, 111.Google Scholar
  32. Neupert, W. M.: 1968, Astrophys. J. Letters 153, 59.Google Scholar
  33. Roy, J. R.: 1972, Solar Phys. 26, 418.Google Scholar
  34. Severny, A. B.: 1969, Nobel Symp. 9, 71.Google Scholar
  35. Simon, G. W. and Noyes, R. W.: 1972, Solar Phys. 22, 450.Google Scholar
  36. Strauss, F. M. and Papagiannis, M. D.: 1971, Astrophys. J. 164, 369.Google Scholar
  37. Švestka, Z.: 1965, Adv. Astron. Astrophys. 3, 119.Google Scholar
  38. Švestka, Z.: 1970, Solar Phys. 13, 471.Google Scholar
  39. Švestka, Z.: 1971, Report of the Meeting of CESRA, 15.Google Scholar
  40. Švestka, Z.: 1972, Ann. Rev. Astron. Astrophys. 10, 1.Google Scholar
  41. Švestka, Z. and Simon, P.: 1969, Solar Phys. 10, 3.Google Scholar
  42. Syrovatsky, S. I. and Shmeleva, O. P.: 1972, Soviet Astron. - A.J. 16, 273.Google Scholar
  43. Takakura, T., Ohki, K., Shibuya, N., Fujii, M., Matsuoka, M., Miyamoto, S., Nishimura, J., Oda, M., Ogawara, Y., and Ota, S.: 1971, Solar Phys. 16, 454.Google Scholar
  44. Thomas, R. J. and Teske, R. G.: 1971, Solar Phys. 16, 431.Google Scholar
  45. Tindo, I. P., Ivanov, V. D., Mandelstam, S. L., and Shuryghin, A. I.: 1972, Solar Phys. 24, 429.Google Scholar
  46. Tindo, I. P., Mandelstam, S. L., and Shuryghin, A. I.: 1973, Solar Phys., in press.Google Scholar
  47. Vorpahl, J. A.: 1972, Solar Phys. 26, 397.Google Scholar
  48. Vorpahl, J. and Zirin, H.: 1970, Solar Phys. 11, 285.Google Scholar
  49. Wood, A. T., Noyes, R. W., Dupree, A. K., Huber, M. C. E., Parkinson, W. H., Reeves, E. M., and Withbroe, G. L.: 1972, Solar Phys. 24, 169.Google Scholar
  50. Zirin, H. and Tanaka, K.: 1973, Solar Phys., in press.Google Scholar

Copyright information

© D. Reidel Publishing Company 1973

Authors and Affiliations

  • Z. Švestka
    • 1
  1. 1.Fraunhofer Institute, Freiburg im BreisgauGermany

Personalised recommendations