Difference between Spatial Distributions of the Hα Kernels and Hard X-ray Sources in a Solar Flare

We present the relation of the spatial distribution of Hα kernels with the distribution of hard X-ray (HXR) sources seen during the 2001 April 10 solar flare. This flare was observed in Hα with the Sartorius telescope at Kwasan Observatory, Kyoto University, and in hard X-rays (HXRs) with the Hard X-ray Telescope (HXT) onboard Yohkoh. We compared the spatial distribution of the HXR sources with that of the Hα kernels. While many Hα kernels are found to brighten successively during the evolution of the flare ribbons, only a few radiation sources are seen in the HXR images. We measured the photospheric magnetic field strengths at each radiation source in the Hα images, and found that the Hα kernels accompanied by HXR radiation have magnetic strengths about 3 times larger than those without HXR radiation. We also estimated the energy release rates based on the magnetic reconnection model. The release rates at the Hα kernels with accompanying HXR sources are 16-27 times larger than those without HXR sources. These values are sufficiently larger than the dynamic range of HXT, which is about 10, so that the difference between the spatial distributions of the Hα kernels and the HXR sources can be explained. Subject headings: Sun: activity — Sun: flares — Sun: chromosphere — Sun: X-rays, gamma rays Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8471, JAPAN Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Aichi 442-8507, JAPAN Nobeyama Radio Observatory, Minamisaku, Nagano, 384-1305, JAPAN