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Dear colleagues<br>
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:<br>
<br>
<a class="moz-txt-link-freetext" href="http://arxiv.org/abs/1106.1591">http://arxiv.org/abs/1106.1591</a><br>
<br>
The abstract is below.<br>
<br>
Best regards<br>
Fabio Reale<br>
<br>
<h1 class="title"><small><small><small>Solar Dynamics Observatory
discovers thin high temperature strands in coronal active regions</small></small></small></h1>
<div class="authors"><span class="descriptor">Authors:</span> Fabio
Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni<br>
Peres, Leon Golub<br>
<br>
<a href="http://arxiv.org/find/astro-ph/1/au:+Golub_L/0/1/0/all/0/1"></a></div>
<blockquote class="abstract">
<span class="descriptor">Abstract:</span> 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.
</blockquote>
<br>
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