Solar Physics

, Volume 149, Issue 2, pp 363–380 | Cite as

X-ray observations of a major eruptive flare behind the limb

  • Kermit L. Smith
  • Keith T. Strong
  • Zdeněk Švestka
  • Marie K. McCabe


We analyze X-ray images and spectra of a coronal structure which extended to altitudes over 130 000 km above an eruptive flare located 20° behind the western solar limb. The images were obtained by the Flat Crystal Spectrometer (FCS) and the spectra were obtained by the Bent Crystal Spectrometer (BCS) aboard the SMM spacecraft. Images in Oviii and Mgxi lines cover the period from before the flare onset (which occurred at 22:31 UT on 16 February, 1986) through 17 UT on 17 February and were used for determination of temperature and emission measure within the structure. BCS obtained Caxix spectra of the coronal event, benefiting from the occultation of the active region behind the solar limb.

The BCS data show, and FCS data confirm, that the temperature, after an initial rise and decline, stayed almost constant for many hours after 04:30 UT on 17 February. This may indicate that initially we observed the rise and decay of post-flare loops, but later the X-ray emission came predominantly from a post-flare giant arch that formed above them. This has been observed in many previous cases. However, a comparison with other events characterized by very high post-flare loops, such as those that occurred on 29 July, 1973 (Skylab data) and on 14 February, 1986 (from this same region), suggests that we may be observing the same system of slowly growing groups all the time. Therefore, we suggest a third possibility, i.e., that such anomalously high loop systems first behave like post-flare loops but gradually take over some characteristics of a post-flare giant arch. The Soft X-ray Telescope aboardYohkoh, with spatial resolution improved by nearly an order of magnitude, might be able to check up on the development of such large-scale coronal structures if proper observational modes are applied after the occurrence of major eruptive flares.


Flare Loop System Emission Measure High Loop Solar Limb 
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  1. Acton, L. W., Culhane, J. L., Gabriel, A. H., and 21 co-authors: 1980,Solar Phys. 65, 53.Google Scholar
  2. Bely-Dubau, F., Gabriel, A. H., and Volonte, S.: 1979,Monthly Notices Roy. Astron. Soc. 189, 801.Google Scholar
  3. De Jager, C. and Švestka, Z.: 1985,Solar Phys. 100, 435.Google Scholar
  4. Heinzel, P. and Karlický, M.: 1987,Solar Phys. 110, 343.Google Scholar
  5. Heinzel, P., Schmieder, B., and Mein, P.: 1992,Solar Phys. 139, 81.Google Scholar
  6. Hick, P.: 1988, ‘Interpretations of Energetic Phenomena in the Solar Corona’, Thesis, State University Utrecht, p. 15.Google Scholar
  7. Hick, P. and Švestka, Z.: 1987,Solar Phys. 108, 315.Google Scholar
  8. Hick, P., Švestka, Z., Smith, K. L., and Strong, K. T.: 1987,Solar Phys. 114, 329.Google Scholar
  9. Kahler, S. W., Sheeley, N. R., Howard, R. A., Koomen, M. J., Michels, D. J., McGuire, R. E., von Rosenvinge, T. T., and Reames, D. V.: 1984,J. Geophys. Res. 89, 209.Google Scholar
  10. Kopp, R. A. and Pneuman, G. W.: 1976,Solar Phys. 50, 85.Google Scholar
  11. Kopp, R. A. and Poletto, G.: 1990,Solar Phys. 127, 267.Google Scholar
  12. Martin, S. F., Švestka, Z., and Bhatnagar, A.: 1989,Solar Phys. 124, 339.Google Scholar
  13. Moore, R., McKenzie, D. L., Švestka, Z., Widing, K. G., and 12 co-authors: 1980, in P. A. Sturrock (ed.),Solar Flares, Skylab Solar Workshop II, p. 341.Google Scholar
  14. Nolte, J. T., Gerassimenko, M., Krieger, A. S., Petrasso, R. D., and Švestka, Z.: 1979,Solar Phys. 62, 123.Google Scholar
  15. Poletto, G. and Kopp, R. A.: 1988,Solar Phys. 116, 163.Google Scholar
  16. Saba, J. L. R. and Strong, K. T.: 1991,Astrophys. J. 375, 789.Google Scholar
  17. Šimberová, S., Karlický, M., and Švestka, Z.: 1992,Solar Phys. 146, 343.Google Scholar
  18. Solar Geophysical Data: 1986, No. 504, Part II, p. 44.Google Scholar
  19. St. Cyr, O. C. and Burkepile, J. T.: 1990, NCAR/TN-352.Google Scholar
  20. Švestka, Z.: 1984,Solar Phys. 94, 171.Google Scholar
  21. Švestka, Z.: 1991,Solar Phys. 135, 419.Google Scholar
  22. Švestka, Z. and Šimberová, S.: 1992,Proceedings IAU Colloq. No. 133,Lecture Notes in Physics 399, 221.Google Scholar
  23. Švestka, Z., Stewart, R. T., Hoyng, P., Van Tend, W., Acton, L. W., Gabriel, A. H., Rapley, C. G., and 8 co-authors: 1982a,Solar Phys. 75, 305.Google Scholar
  24. Švestka, Z., Dodson-Prince, H. W., Martin, S. F., Mohler, O. C., Moore, R. L., Nolte, J. T., and Petrasso, R. D.: 1982b,Solar Phys. 78, 271.Google Scholar
  25. Švestka, Z., Fontenla, J. M., Machado, M. E., Martin, S. F., and Poletto, G.: 1987,Solar Phys. 108, 237.Google Scholar
  26. Thomas, R. J., Starr, R., and Crannell, C. J.: 1985,Solar Phys. 95, 323.Google Scholar
  27. Tsuneta, S., Acton, L., Bruner, M., Lemen, J., Brown, W., Carvalho, R., Catura, R., Freeland, S., Jurchevich, B., Morrison, M., Ogawara, Y., Hirayama, T., and Owens, J.: 1991,Solar Phys. 136, 37.Google Scholar
  28. Watanabe, T. and Iwata, A.: 1988,Proc. Res. Inst. Atmospherics, Nagoya University, Vol. 35, p. 59.Google Scholar

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Kermit L. Smith
    • 1
  • Keith T. Strong
    • 1
  • Zdeněk Švestka
    • 2
    • 3
  • Marie K. McCabe
    • 4
  1. 1.Lockheed Palo Alto Research LaboratoryPalo AltoUSA
  2. 2.SRON Laboratory for Space ResearchUtrechtThe Netherlands
  3. 3.CASS, UCSDLa JollaUSA
  4. 4.Institute for AstronomyUniversity HawaiiHonoluluUSA

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