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[54.07] Above the Loop-top Non-thermal Hard X-ray Source in a Partially Occulted Flare

P. Balciunaite, S. Krucker (SSL, UCB), R. P. Lin (Department of Physics, UCB; SSL, UCB)

We present RHESSI hard X-ray imaging, spectroscopy, and source motion analysis of a long-duration GOES M 4.5 class flare (18 Nov 2003 0923-1101 UT), whose footpoints were occulted by the east limb of the Sun. During the rise phase of the flare a non-thermal hard X-ray source is seen above ~20 keV with a spectral power-law index around 6. The source is initially detected ~50 arcseconds above the limb and seen to rise with a velocity of ~12 km/s. Its time profile varies on a scale of tens of seconds. At lower energies, a thermal hard X-ray source with a temperature of up to 17 MK is detected ~10 arcseconds below the non-thermal source, and seen to be rising with a lower velocity of ~7 km/s. Its time variation is slow and gradual, similar to that of the GOES time profile. Both sources are seen above GOES SXI soft X-ray and SOHO EIT EUV loops. We also discuss the energetics of the non-thermal above-the-loop-top source.

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Bulletin of the American Astronomical Society, 36 #2
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