The birth of giant post-flare arches

Abstract

Using short accumulation times, we have succeeded in the detection in HXIS images of the initial growth of the giant post-flare arch of 6 November, 1980 at 14:44 UT and part of the initial growth of the giant arch of 7 November, 1980 at 04:30 UT. These observations are relevant to the problem of the origin of giant arches: the fact that the arch of 6 November was imaged more than half an hour before the first flare loops had been recorded in the associated flare, proves that giant arches cannot: be interpreted as upper products of the reconnection process that creates the growing systems of flare loops (as the original interpretation by Švestka et al. (1982a) suggested). However, also the alternative hypothesis by Poletto and Kopp (1988) that these structures originate through a reconnection process in a peripheral, large-scale configuration meets with difficulties: after the initial rise, the maximum brightness in both arches seems to descend, until a much slower rise was resumed about two hours later.