A nice paper and an important contribution to the debate. But the jury
is still out. We may never resolve this without real spectroscopic
evidence of the very hot component. Where is our future spectroscopy
coming from??
Alan Gabriel
Le 09/06/2011 10:52, Fabio Reale a écrit :
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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Alan GABRIEL alan.gabriel@ias.u-psud.fr
Institut d'Astrophysique Spatiale tel : (33) 1 69 85 85 10
Batiment 121, Universite Paris XI fax : (33) 1 69 85 86 75
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