Abstract
NOAA active region 6659, during its June 1991 transit across the solar disk, showed highly sheared vector magnetic field structures and produced numerous powerful flares, including five white-light flares. Photospheric vector magnetograms of this active region were obtained at the Huairou Solar Observing Station of the Beijing Astronomical Observatory. After the resolution of the 180° ambiguity of the transverse magnetic field and transformation of off-center vector magnetograms to the heliographic plane, we have determined the photospheric vertical current density and discussed the relationship with powerful flares. The following results were obtained: (a) The powerful 3B/X12 flare on June 9, 1991 was triggered by the interaction between the large-scale electric current system and magnetic flux of opposite polarity. (b) The kernels of the powerful Hβ flare (sites of the white-light flare) were close to the peaks of the vertical electric current density. (c) Some small-scale structures of the vertical current relative to the magnetic islands of opposite polarity have not been found. This probably implies that the electric current is not always parallel to the magnetic field in solar active regions.
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Abramenko, O. I., Gopasyuk, S. I., and Ogir, M. S.: 1991,Solar Phys. 134, 287.
Canfield, R. C., Fan, Y., Leka, K. D., McClyment, A. N., Wuelser, J., Lites, B. W., and Zirin, H.: 1991, in L. J. November (ed.),Solar Polarimetry, Sacramento Peak Summer Workshop, p. 296.
Chen, J. and Zhang, H.: 1991,Acta Astrophys. Sinica 12, 82.
Ding, Y. J., Hagyard, M. J., Deloach, A. C., Hong, Q. F., and Liu, X. P.: 1987,Solar Phys. 109, 307.
Gary, G. A. and Hagyard, M. J.: 1990,Solar Phys. 126, 21.
Hagyard, M. J., Smith, J. R., Jr., Teuber, D., and West, E. A.: 1984,Solar Phys. 91, 115.
Krall, K. R., Smith, J. B., Jr., Hagyard, M. J., West, E. A., and Cummings, N. P.: 1982,Solar Phys. 79, 59.
Moreton, G. and Severny, A. B.: 1968,Solar Phys. 3, 282.
Lin, Y. Z. and Gaizauskas, V.: 1987,Solar Phys. 109, 81.
Sakurai, T., Ichimoto, K., Hiei, E., Irie, M., Kumagai, K., Miyashita, M., Nishino, Y., Yamaguchi, K., Geng, F., Kambry, M. A., and Zhao, Z.: 1992,Publ. Astron. Soc. Japan 44, L7.
Schmieder, B., Hagyard, M. J., Ai, G. X., Zhang, H. Q., Kalmán, B., Györi, L., Rompolt, B., Démoulin, P., and Machado, M. E.: 1994,Solar Phys. 150, 199.
Zhang, H.: 1993,Astron. Astrophys., submitted.
Zhang, H., Ai, G., and Wang, T.: 1993, in T. Sakurai (ed.),Proceedings of 2nd China—Japan Solar Physics Workshop, in press.
Zhang, H., Ai, G., Yan, X., Li, W., and Liu, Y: 1994,Astrophys. J., in press.
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Zhang, H., Wang, T. Vertical current and a 3B/X12 flare in a highly sheared active region (NOAA 6659) on June 9, 1991. Sol Phys 151, 129–136 (1994). https://doi.org/10.1007/BF00654086
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DOI: https://doi.org/10.1007/BF00654086