Hi Markus,
Maybe the paper wasn’t clear, but all
the simulations we present have asymmetric heating. That’s what the
asymmetry factor in the third column of the table refers to. The condensations
are definitely not stationary, as we discuss in several places and can be
clearly seen in Figure 1, for example. All of the condensations are eventually
pushed to the chromosphere by a pressure imbalance. Also, there is
evaporation happening during most of the evolution, as discussed on page 10,
for instance.
Please let me know if you need more
details.
Thanks,
Jim
From:
loops-bounces@solar.physics.montana.edu
[mailto:loops-bounces@solar.physics.montana.edu] On Behalf Of Markus J.
Aschwanden
Sent: Monday, December 07, 2009 4:47 PM
To: A mailing list for scientists involved in the observation and
modeling of solar loop structures
Subject: Re: [Loops] loops and thermal nonequilibrium
Dear Jim,
I read your paper with interest. You made a faithful attempt
to explain five observed
loop properties, which I really appreciate. The
hydrodynamic simulations indeed show
some puzzling condensation blobs that remain at
stationary locations that seem not
to correspond to observations. However, I have the
impression that this puzzling
effect, which you use as main argument that cooling loops
are not consistent
with observations, is an artifact of the perfect pressure
balance in your model.
When you watch TRACE movies, you will see that real coronal
loops always evolve:
sway, expand, twist, or shrink on time scales of an hour,
which slowly changes the
pressure balance along the loop and would move
condensation blobs to one side.
Loops are also always asymmetric, have diverging and
converging cross-sections,
which causes siphon flows and drains condensation blobs to
one side. So, I think
that the simulations are too idealized to tell us the
long-term evolution.
It is like balancing a ball on the Eiffeltower - an
equilibrium solution is mathematically
possible - but is impossible in reality, there are always
vibrations or wind ...
Perhaps you can repeat a simulation by superimposing some
slowly-varying
pressure disturbances, use a varying cross-section, and fill
it by upflows from
gentle chromospheric evaporation (more like in flares).
Cheers,
Markus
On Dec 4, 2009, at 2:04 PM, Klimchuk, James A. (GSFC-6710)
wrote:
Dear
Loops Friends,
If you are interested, the attached paper shows that coronal loops cannot be
explained by thermal nonequilibrium. The results appear to rule out the
widespread existence of coronal heating that is both highly concentrated low in
the corona and steady or quasi-steady (slowly varying or impulsive with a rapid
cadence). Comments are welcomed.
Best
wishes,
Jim
********************************************************************************
James
A. Klimchuk
NASA
Goddard Space Flight Center
Solar
Physics Lab, Code 671
Bldg.
21, Rm. 158
Greenbelt,
MD 20771
USA
Phone:
1-301-286-9060
Fax:
1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov
********************************************************************************
<klimchuk_submitted.pdf>_______________________________________________
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____________________________________________
Dr. Markus J. Aschwanden
Solar & Astrophysics Laboratory
Lockheed Martin Advanced Techology Center
Org. ADBS, Bldg. 252
3251 Hanover St., Palo Alto, CA 94304, USA
Phone: 650-424-4001, FAX: 650-424-3994
e-mail: aschwanden@lmsal.com
_______________________________________
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