Abstract
Through coordinated observations made during the Max'91 campaign in June 1989 in Potsdam (magnetograms), Debrecen (white light and Hα), and Meudon (MSDP), we follow the evolution of the sunspot group in active region NOAA 5555 for 6 days. The topology of the coronal magnetic field is investigated by using a method based on the concept of separatrices - applied previously (Mandriniet al., 1991) to a magnetic region slightly distorted by field-aligned currents. The present active region differs by having significant magnetic shear. We find that the Hα flare kernels and the main photospheric electric current cells are located close to the intersection of the separatrices with the chromosphere, in a linear force-free field configuration adapted to the observed shear. Sunspot motions, strong currents, isolated polarities, or intersecting separatrices are not in themselves sufficient to produce a flare. A combination of them all is required. This supports the idea that flares are due to magnetic reconnection, when flux tubes with field-aligned currents move towards the separatrix locations.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Abramenko, V. I., Gopasyuk, S. I., and Ogir, M. B.: 1991,Solar Phys. 134, 287.
Canfield, R. C., de La Beaujardière, J. F., and Leka, D. D.: 1991,Phil. Trans. Roy. Soc. London A336, 381.
Démoulin, P. and Priest, E. R.: 1992,Astron. Astrophys. 258, 535.
Démoulin, P., Hénoux, J. C., and Mandrini, C. H.: 1992,Solar Phys. 139, 105.
Démoulin, P., Priest, E. R., and Ferreira, J.: 1991,Astron. Astrophys. 245, 289.
Démoulin, P., van Driel-Gesztelyi, L., Schmieder, B., Hénoux, J. C., Csepura, G., and Hagyard, M. J.: 1993,Astron. Astrophys. 271, 292.
Dezsö, L., Gerlei, O., and Kovács, Á.: 1988, ‘Debrecen Photoheliographic Results’,Publ. Debrecen Obs. Heliographic Series, No. 1, p. 11.
Ding, Y. J., Hagyard, M. J., de Loach, A. C., Hong, Q. F., and Liu, X. P.: 1987,Solar Phys. 109, 307.
Gaizauskas, V.: 1989,Solar Phys. 121, 135.
Gorbachev, V. S. and Somov, B. V.: 1987,Solar Phys. 109, 81.
Hagyard, M. J.: 1988,Solar Phys. 115, 107.
Hénoux, J. C. and Somov, B. V.: 1987,Astron. Astrophys. 185, 305.
Hofmann, A. and Kálmán, B.: 1991,Astron. Astrophys. 241, 203.
Hofmann, A., Ruždjak, V., and Vršnak, B.: 1989,Hvar Obs. Bull. 13, No. 11.
Lin, Y. and Gaizauskas, V.: 1988,Solar Phys. 115, 107.
Mandrini, C. H., Démoulin, P., Hénoux, J. C., and Machado, M. E.: 1991,Astron. Astrophys. 250, 541.
Mandrini, C. H., Rovira, M. G., Démoulin, P., Hénoux, J. C., Machado, M. E., and Wilkinson, L.: 1993,Astron. Astrophys. 272, 609.
Mein, P.: 1977,Solar Phys. 54, 45.
Newton, H. W. and Nunn, M. L.: 1951,Monthly Notices Roy. Astron. Soc. 111, 413.
Priest, E. R.: 1991,Phil. Trans. Roy. Soc. London A336, 363.
Romanov, V. A. and Tsap, T. T.: 1990,Soviet Astron. 34, 656.
Schmieder, B., van Driel-Gesztelyi, L., Hénoux, J. C., and Simnett, G. M.: 1991,Astron. Astrophys. 244, 533.
Somov, B. V.: 1986,Adv. Space Res. 6(6), 177.
Staude, J.: 1970a,Solar Phys. 12, 84.
Staude, J.: 1970b,Solar Phys. 15, 102.
Vekstein, G. E., Priest, E. R., and Amari, T.: 1991,Astron. Astrophys. 243, 492.
Wilkinson, L. K., Emslie, A. G., and Gary, G. A.: 1992,Astrophys. J. 392, L39.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
van Driel-Gesztelyi, L., Hofmann, A., Démoulin, P. et al. Relationship between electric currents, photospheric motions, chromospheric activity, and magnetic field topology. Sol Phys 149, 309–330 (1994). https://doi.org/10.1007/BF00690619
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00690619