Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

I. M. Podgomy, and A. I. Podgomy At the beginning Фм and Ф$ increase linearly. Linear extrapolation 23.10.2003 shows that the X5.4 flare occurs at <Dn ~ 5 10 22 Mx и ~ 31022 Mx. The magnetic field configuration changes only weakly. At that time dON/dt~4 10 Mx/s and dOs/dt ~ 8 10 16 Mx/s. The SOHO data for AR10486 are very convenient for investigation of the active region magnetic field at the flare appearing. The time of magnetic map measurements has coincided with the most powerful flare (X I7, S18E20, 28.10.2003, W l l i l O ) with accuracy of 1 s. The magnetic flux o f the AR10486 both magnetic components (N and S) remain constant during the flare. Magnetic field distributions around the flare are presented in fig. 4. The change of the magnetic flux is less than 1 percent per hour. Only noticeable peculiarity is a narrow local field maximum at the flare time which does not produce valuable change o f the magnetic flux. This maximum is marked by the arrow. But such fluctuations occur during time of all active region evolution. It is impossible to exclude that such maximum can initiate current sheet instability. 2003-10-28 09:35:03 R „ = 3 0 0 0 П 2003-10-28 11:11:03 - B n=3000 G 2003-10-28 12:47:03 -Bn=3000 G AR 10486 Bsmax =2450<3 N = 7.4 10 Mx Ф_ = 6.3 1022 Mx о Fig. 4. Magnetic field distribution in the active region before the powerful solar flare, in the flare time, and after the flare. Conclusion The powerful solar flares appeared above AR10486 at magnetic flux bigger than 10 22 Mx. Similar results shows investigations of others active regions. Magnetic field distribution during flares, including X I 7 flare, does not show any change that can be associated with energy input from the photosphere to flaring region. This result can be considered as an independent evidence of slow energy accumulation in the corona before the flare. Energy explosive release occurs producing the flare. Such scenario is in agreement with the electrodynamical solar flare model [ 6 - 8 ]. A cknow ledgm ents. This work was supported by RFBR grant № 09-02-00043. R eferences 1. Livingston W., Penn M. EOS 90, 257-264 (2009). 2. Podgomy I. М., Podgomy A. I. Physics of Auroral Phen., Proc. o f the Apatity 32-nd Seminar P 127 2009 P Ш 2007УA' L’ POd8°my L M '’ MCShalkina N - S- PhySiCS o f Auroral p hen„ Proc. o f the Apatity 30-th Seminar. 4. Ishkov V. N. Astronomical and Astrophysical Trans. 20, 563-569 (2001). 5. Wang J., Zhao М., Zhou G. Ap. J. 690, 862 (2009). 6 . Podgomy A. I., Podgomy I. M. Solar Phys. 139, 125 (1992). 7. Podgomy A. I., Podgomy I. M. Astronomy reports. 50, 842 (2006). 8 . Podgomy A. I., Podgomy I. M. Astronomy reports. 52. 6 6 6 (2008), 9. Lin R. P, Krucker S., Hurford G. J., et al. Astrophys. J. 595, L69 (2003). 10. Krucker S. et al. Proceedings of ESPM-12. 2008. http://esDm.kis.uni-freih.irp Hp 90