HR: 1330h
AN: SH22A-0176    [PDF]
TI: An Energy Build-up Process of Flares on a Continuously Emerging Active Region
AU: * Morita, S
EM: morita@eitv7.nascom.nasa.gov
AF: NRC/NASA/GSFC, NASA Goddard Space Flight Center, Mail Code 682.3, Building 26, Room 001, Greenbelt, MD 20771 United States
AB: This is a preliminary report of a possible model of an energy build-up process of flares for the case where flares occur on continuously emerging and developing active region. In March 2003, about 40 flares occurred in the same active region NOAA10314 within 6 days (March~15 -- March~20). These flares include two X-class flares, six M-class flares, and some sub-M-class flares. Many of them had some common characteristic features. This particular active region has a dual bipolar magnetic configuration that emerged on March 13, and was continually growing through this period. We report the characteristics of these flares using SoHO/EIT images, and pay attention to the evolution of the active region NOAA10314 since its emergence using SoHO/MDI magnetograms. We found: (1) Separating motions between positive and negative polarities of both the dipoles of this active region are seen in a time series of MDI magnetograms. This suggests that these dipole areas are currently emerging flux regions. (2) The photospheric magnetic neutral line (``main neutral line'') between both expanding eastern and western dipoles is rotating but stable. This line is the contact line between both expanding dipoles, thus magnetic intensities on the photosphere in this active region were strongest on both sides of the ``main neutral line'', and the line was stable throughout this period. (3) At least 26 events occurred along the ``main neutral line''. Another 11 events also showed correspondence to this ``main neutral line''. (4) We see structures resembling dual separatrix surfaces on both sides of the flaring structures in EIT images before March~17. (5) In TRACE images, we frequently see a lot of tiny brightenings and mass motions near the photosphere in the area outside of the flaring region. This area corresponds to the eastern dipole area in item (1). Based on these observations, we present a possible model of an energy build-up process in flares. We also find similar properties in other flares, which occurred on another growing active region. Acknowledgment: This research is supported by the National Research Council.
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7509 Corona
DE: 7519 Flares
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting