Observations of 1000 km s⁻¹ Doppler shifts in 10⁷ K solar flare supra-arcade

Abstract

An X1.5 flare on the west limb of the Sun on 21 April 2002 developed a large supra-arcade about 30 min after flare onset. The growth of the supra-arcade can be followed in both TRACE 195 Å images and SUMER spectra. Its growth seems to be associated with dark (in TRACE images), sunward moving channels that descend onto the arcade from above. SUMER recorded Doppler shifts of 800-1000 km s⁻¹ in Fe xxi 1354 Å from positions where this sunward flow interacts with the arcade tops. We describe the observations, focusing on the relationship of the high Fe xxi line shifts to the sunward moving dark flows.