Abstract:
As one of the most spectacular energy release events in the solar
system, solar flares are generally powered by magnetic reconnection
in the solar corona. As a result of the re-arrangement of magnetic
field topology after the reconnection process, a series of new loop-
like magnetic structures are often formed and are known as flare
loops. A hot diffuse region, consisting of around 5–10 MK plasma,
is also observed above the loops and is called a supra-arcade fan.
Often, dark, tadpole-like structures are seen to descend through the
bright supra-arcade fans. It remains unclear what role these so-called
supra-arcade downflows (SADs) play in heating the flaring coronal
plasma. Here we show a unique flare observation, where many
SADs collide with the flare loops and strongly heat the loops to a tem-
perature of 10–20 MK. Several of these interactions generate clear
signatures of quasi-periodic enhancement in the full-Sun-integrated
soft X-ray emission, providing an alternative interpretation for
quasi-periodic pulsations that are commonly observed during solar
and stellar flares.
