Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Post-flare coronal loop interaction


High-resolution images of post-flare loop systems in Fexiv (5303 Å) and Fex (6374 Å) display occasional transient enhancements at the projected intersection of some loops. The brightness of a green-line enhancement gradually increases to a marked maximum and then fades with a lifetime of the order of thirty minutes. The red-line image at the same location, although fainter, shows the same overall characteristics, its maximum following that of the green-line on average by 8.6 min. Hα then becomes more evident and reaches a maximum in extent on average 9.3 min after the red-line maximum. The phenomenon is interpreted as a process of localized loop coalescence involving partial magnetic reconnection. Estimates of the electron density are derived from the cooling time following the initial heating of the plasma in the immediate vicinity of the X-point of interaction. Similar estimates for the energy dissipated, equivalent to a very small flare, are derived by two independent methods.

This is a preview of subscription content, log in to check access.


  1. Deeg, H. J., Borovsky, J. E., and Duric, N.: 1991,Phys. Fluids B (Plasma Physics) 3, 2660.

  2. Den, O. G. and Somov, B. V.: 1989,Soviet Astron. 33, 149.

  3. Dungey, J. W.: 1953,Phil. Mag. 44, 725.

  4. Emslie, A. G.: 1981,Astrophys. J. 22, L171.

  5. Forbes, T. G., Malherbe, J. M., and Priest, E. R.: 1989,Solar Phys. 120, 285.

  6. Greene, J. M.: 1988,J. Geophys. Res. 93, 8582.

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

  8. Kundu, M. R.: 1983,Solar Phys. 86, 205.

  9. Kundu, M. R.: 1985, ‘Unstable Current Systems and Plasma Instabilities in Astrophysics’,Proc. IAU Symp. 170, 185.

  10. Kundu, M. R. and White, S. M.: 1990,Adv. Space Res. 10, 85.

  11. Kundu, M. R., Schmahl, E. J., and Velusamy, T.: 1982,Astrophys. J. 253, 963.

  12. Kundu, M. R., Machado, M. E., Erskine, F. T., Rovira, M. G., and Schmahl, E. J.: 1984,Astron. Astrophys. 132, 241.

  13. Lang, K. R. and Willson, R. F.: 1984,Adv. Space Res. 4, 105.

  14. Lin, R. P.: 1986, in E. Tandberg-Hanssenet al. (eds.),Solar Flares and Coronal Physics, NASA Conference Publication 2421, p. 98.

  15. MacCombie, W. J. and Rust, D. H.: 1979,Solar Phys. 61, 69.

  16. Machado, M. E.: 1982,Adv. Space Res. 2, 115.

  17. Machado, M. E.: 1987,Solar Phys. 113, 57.

  18. Malville, J. M.: 1978, ‘Physics of Solar Prominences’,Proc. IAU Colloq. 44, 214.

  19. Mandrini, C. H., Machado, M. E., Hernandez, A. M., and Rovira, M. G.: 1990,Adv. Space Res. 10(9), 115.

  20. Moore, R., McKenzie, D. L., Švestka, Z., Widing, K. G., Antiochos, S. K., Dere, K. P., Dodson-Prince, H. W., Hiei, E., Krall, K. R., Krieger, A. S., Mason, H. E., Petrasso, R. D., Pneuman, G. W., Silk, J. K., Vorpahl, J. A., and Withbroe, G. L.: 1980, in P. A. Sturrock (ed.),Skylab Solar Workshop II: Solar Flares, Colorado Associated University Press, p. 341.

  21. Nakajima, H., Tajima, T., Brunel, F., and Sakai, J.: 1985,Bull. Faculty Eng. Toyama Univ. 36, 39.

  22. Priest, E. R.: 1982,Solar Magneto-Hydrodynamics, D. Reidel Publ. Co., Dordrecht, Holland.

  23. Pritchett, P. L. and Wu, C. C.: 1979,Phys. Fluids 22, 2140.

  24. Raymond, J. C., Cox, D. P., and Smith, B. W.: 1976,Astrophys. J. 204, 290.

  25. Rust, D. M. and Somov, B. V.: 1984,Solar Phys. 93, 95.

  26. Sakai, J-I. and de Jager, C.: 1989a,Solar Phys. 123, 389.

  27. Sakai, J-I. and de Jager, C.: 1989b,Solar Phys. 123, 393.

  28. Sakai, J-I. and de Jager, C.: 1991,Solar Phys. 134, 329.

  29. Smartt, R. N. and Zhang, Z.: 1987, in G. Athay and D. S. Spicer (eds.),Theoretical Problems in High-Resolution Solar Physics II, NASA Conference Publication 2483, p. 129.

  30. Smartt, R. N. and Zhang, Z.: 1992, in J. Mariska, V. Domingo, and A. Poland (eds.),Coronal Streamers, Coronal Loops, and Coronal and Solar Wind Composition, ESA SP-348, p. 185.

  31. Smartt, R. N., Dunn, R. B., and Fisher, R. R.: 1981,SPIE 288, 395.

  32. Spicer, D. S. and Švestka, Z.: 1983,Solar Phys. 87, 271.

  33. Švestka, Z. and Poletto, G.: 1985,Solar Phys. 97, 113.

  34. Švestka, Z., Fontenla, J. M., Machado, M. E., Martin, S. F., Neidig, D. F., and Poletto, G.: 1987,Solar Phys. 108, 237.

  35. Tajima, T., Brunel, F., and Sakai, J.: 1982,Astrophys. J. 258, L45.

  36. Tajima, T., Brunel, F., Sakai, J., Vlahos, L., and Kundu, M. R.: 1985, ‘Unstable Current Systems and Plasma Instabilities in Astrophysics’,Proc. IAU Symp. 107, 197.

  37. Tajima, T., Sakai, J., Nakajima, H., Kosugi, T., Brunel, F., and Kundu, M. R.: 1987,Astrophys. J. 321, 1031.

  38. Tamano, T.: 1991,Solar Phys. 134, 187.

Download references

Author information

Additional information

Operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Smartt, R.N., Zhang, Z. & Smutko, M.F. Post-flare coronal loop interaction. Sol Phys 148, 139–151 (1993).

Download citation


  • Flare
  • Similar Estimate
  • Magnetic Reconnection
  • Loop System
  • Cooling Time