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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