Abstract

We estimated the released magnetic energy via magnetic reconnection in the corona by using photospheric and chromospheric features. We observed an X2.3 flare, which occurred in active region NOAA9415 on 2001 April 10, in Hα with the Sartorius Telescope at Kwasan Observatory, Kyoto University. Comparing the Hα images with the hard X-ray (HXR) images obtained with Yohkoh/HXT, we see only two HXR sources which are accompanied by Hα kernels. At these Hα kernels the large energy release is thought to be larger than at other Hα kernels. We estimated the energy release rates at each Hα kernel by using the photospheric magnetic field strength and the separation speed of the Hα flare ribbons at the same location. The estimated energy release rates at the Hα kernels associated with the HXR sources are locally large enough to explain the different appearance. Their temporal evolution also shows peaks corresponding to HXR bursts.