The Topology of Magnetic Reconnection in Solar Flares

16motion, an explanation for the various types of movement is of great interest. For example,Fletcher and Hudson (2002) compare observed footpoint motions to those predicted byflare models. They conclude that footpoint motions do not resemble the simple increasein separation expected in 2D reconnection models. For the 29 October 2003 X10 flare,Krucker et al. (2005) analyze the HXR footpoint velocity variations and the underlyingphotospheric magnetic field strength. They observe that the footpoint velocity is generallyslower in the areas where magnetic field strength is higher. Bogachev et al. (2005)analyze the HXR footpoint motions of 31 flares observed by the Yohkoh Hard X-ray Telescope(HXT; Kosugi et al., 1991) with respect to neutral lines calculated from photosphericmagnetograms. They find that only 13% of footpoints move away from the neutral line.Several groups have sought to explain flare features via topological models. Gorbachevand Somov (1988) describe a topological model which satisfies the observational requirementsof two-ribbon flares, such as HXR ‘knots’ in the ribbons. In their model, the activeregion separator, the special field line on which reconnection occurs, directs the releasedenergy flux to the flare ribbons. Somov et al. (1998) present a reconnection model whichexplains the observation that the separation of HXR footpoints in ’less impulsive’ flares(impulsive phase t > 30-40 s) tends to increase while in ’more impulsive’ flares (t < 30-40 s), it decreases. They attribute the increase/decrease in footpoint separation to an increase/decreasein the longitudinal field at the flaring separator, increasing/decreasing thelength of the reconnected field lines.While substantial work has been done in the areas of multi-wavelength analysis of solarflares and coronal magnetic field modeling, little attention has been given to the combinationof these two fields. Metcalf et al. (2003) describe a coincidence between magneticseparatricies and features of the 25 August 2001 white-light flare. They conclude that theHXR footpoint motions present in this flare are consistent with reconnection at a separator.Here, we explore three flares by examining the relationship between HXR footpoints and