Some quick comments….
1. I agree with Markus and Marco
that there is, in principle, no problem having impulsive heating (nanoflares) in
the low atmosphere (chromosphere and transition region) of unipolar regions, as
long as the field is “tangled.” The resolvable events that Harry
mentions are interesting and important, but different from ordinary coronal
heating.
2. However, the transition region is
an extremely thin layer that moves up and down flux tubes in response to
changes in the coronal pressure resulting from heating and cooling. It is
very difficult for me to see why the magnetic energy dissipation that gives
rise to heating should always follow this layer. Dissipation in the
thicker chromosphere is much easier to swallow.
3. The ten arguments that Markus
gives in his paper are consistent with heating in the transition region, but
they are also consistent with heating in the corona! Thus, they do not
disprove coronal nanoflares. Perhaps we can discuss this in
Cheers,
Jim
From:
loops-bounces@solar.physics.montana.edu
[mailto:loops-bounces@solar.physics.montana.edu] On Behalf Of Markus J. Aschwanden
Sent: Thursday, March 05, 2009
10:16 AM
To: Hugh Hudson; A mailing list
for scientists involved in the observation and modelingof solar loop structures
Subject: [Loops] summaries on
nanoflare debates in "coronal loop workshops"
Dear Hugh,
Jim Klimchuk sent a great summary of the current status of a nanoflare
model around,
so it deals with all the PROs. An outside reader who wants to hear both
sides might be
interested to hear also the CONs, which you could find in the ApJ
Letter entitled
"An observational test that disproves coronal nanoflare heating
models" (Aschwanden
2008, ApJ 672, L135). The arguments made therein do not dismiss
nanoflares
altogether, but come to the conclusion that they occur in the
transition region,
rather than in the corona (as Parker originally suggested).
Cheers,
Markus
On Mar 3, 2009, at 7:32 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear loops friends,
Here is a paper
I wrote for the Hinode II conference proceedings. In it, I try to do
three things: (1) review the arguments leading to the conclusion that
warm EUV loops must by bundles of strands heated by storms of nanoflares (the
flow chart some of you have asked about); (2) reconcile the
isothermal/multi-thermal debate in terms of the duration of the nanoflare
storm; and (3) address the possibility that loops can be explained by thermal
nonequilibrium. Comments are welcomed.
Thanks,
James A. Klimchuk
____________________________________________
Dr. Markus J.
Aschwanden
Solar &
Astrophysics Laboratory
Lockheed Martin
Advanced
Org. ADBS, Bldg. 252
Phone: 650-424-4001,
FAX: 650-424-3994
e-mail: aschwanden@lmsal.com
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