Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

/. M Podgorny and A. I. Podgorny Another feature of AR, causing big solar flares, is a compact arrangement of sunspots, providing a strong magnetic field gradient across the polarity inversion line. Only above such regions the strong current sheet can be created in the corona. A number of P-type AR with large magnetic fluxes of northern and southern polarities, which separated by a distinct line of field inversion, have been observed in April-May 2011 (NOAA 11183, NOAA 11226, etc.). These regions are not produced X-class flares. The existence of sources of the northern and southern polarities throughout у-region, which produce complicated field with distribution of a multipolar character, leads to the formation of several singular magnetic lines in the corona [11]. In the vicinity of each singular line a current sheet can be formed. The series of flares is explained by appearance of several current sheets. The absence of strong changes in the magnetic field distribution is clearly seen in all the investigated flares, including the long-X3.8 flare in AR 10720, is indicating the energy release in the corona. The conservation of magnetic flux in active regions during a flare has been reported also in [7]. These results demonstrate that energy released during the flare is accumulated in the corona before this flare. Such energy accumulation in a current sheet is demonstrated in 3D MHD numerical simulation, when initial and boundary conditions have been constructed from magnetic field measurements in a real active region. Acknowledgments. This work is supported by 22 Program of Presidium RAS. References 1. Lin R.P., Krucker S., Hurford, G.J. et al. Astrophys. J. V. 595, L69 (2003). 2. Masuda S., Kosugi Т., Нага H., Tsuneta S., Ogawara Y. A Nature. 371, № 6497,495 (1994). 3. Bilenko IA ., Podgorny A.I., Podgorny I.M. Solar Phys. 207, 323 (2002). 4. Podgorny A. I., Podgorny I. M. Geomagnetism and Aeronomy, 52, 162 (2012). 5. Ishkov V. N. Astronomical and Astrophysical Trans. 20, 563 (2001). 6 . Podgorny I.M., Podgorny A.I. Phys. Auroral Phen. Proc. 33 Annual Seminar. Apatity 02-05 March 2010. P. 87. 7. Podgorny A. I., Podgorny I. M. Astronomy Reports. 55, 629 (2011). 8 . E. Robbrecht. Rhodes-ESPM-13. Report. 2011. 9. Wang J., Zhao М., and Zhou G. Astrophys. J., 690, 862 (2009). 10. Jiang Y., Zheng R., Yang J., et al. Astrophys. J., 744, 50 (2011). 11. Podgorny A. I., Podgorny I.M. Astronomy Reports. 52, 666 (2008). В normal Multipolar distribution Between flares X3.6 2003-05-28 00:27 and X1.2 2003-05-29 01:05 фм=1.69-10“ Мх ф5 =1.68-10 3000 Gauss AR 10365 2003-05-28 00:02:59 Bipolar distribution with one neutral line No flare •5000 Gauss AR 11190-92 2011-04-13 17:09:46 фн=1.64-10 4>S 1.58 Ю^Мх 10-3 X a 00 M о £ 10 С c 1 в 5 5 ю 'г A < Ю О Ю-® I ! f ! j j l j P.. yin 12 13 14 Apr.. 15 Fig. 5. The distributions of the magnetic field in AR’s with strong magnetic flux for y-type and P-type regions. X-rays shown are at the bottom. 91