Dear colleagues
please find at the following link the preprint of a work
accepted
for publication on the ApJ Letters, showing new strong evidence of
finely-structured loops with impulsive nanoflare activity in
active
regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards
Fabio Reale
Solar Dynamics Observatory
discovers thin high temperature strands in coronal active
regions
Authors:
Fabio
Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca,
Giovanni
Peres, Leon Golub
Abstract:
One scenario proposed to
explain the million degrees solar corona is a
finely-stranded corona where each strand is heated by a rapid
pulse.
However,
such fine structure has neither been resolved through direct
imaging
observations nor conclusively shown through indirect
observations of
extended
superhot plasma. Recently it has been shown that the observed
difference in
appearance of cool and warm coronal loops (~1 MK, ~2-3 MK,
respectively) --
warm loops appearing "fuzzier" than cool loops -- can be
explained by
models of
loops composed of subarcsecond strands, which are impulsively
heated up
to ~10
MK. That work predicts that images of hot coronal loops (>~6
MK)
should again
show fine structure. Here we show that the predicted effect is
indeed
widely
observed in an active region with the Solar Dynamics
Observatory, thus
supporting a scenario where impulsive heating of fine loop
strands
plays an
important role in powering the active corona.
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