Imaging Spectroscopy of a Gradual Hardening Flare on 2000 November 25

Here we see an explanation of flare events that display gradual flattening of the hard X-ray spectrum, or "SHH" (soft-hard-harder) in X-ray flare jargon. This nice paper describes "dripping," which the Archivist thinks must be a synonym for slow precipitation, as part of the process that accompanies long-term trapping of electrons in flaring coronal magnetic loops. This is a reasonable idea - of limited newness - but there are few cartoons that show it. The cartoon shows injection in the typical reconnection scenario, implying that it somehow happens during time-series peaks but shuts off during time-series valleys, as the source pulsates. Here the magic wand of magnetic reconnection seems to be waving twice: first to accelerate particles, and second to allow them to populate flux tube. Mercifully the authors don't dwell on the details here - why should they, since a reconnection model (MHD) has no particles at all, and therefore no hard X-rays?

       This work is based on the single event SOL2000-11-25, as observed by Yohkoh - with this observatory one could make the first imaging observations of sucn an event, with clear evidence for trapping in large-scale coronal loops.