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.govmailto:James.A.Klimchuk@nasa.gov Home page: http://hsd.gsfc.nasa.gov/staff/bios/cs/James_Klimchuk.html
********************************************************************************
<klimchuk_submitted.pdf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edumailto:Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
____________________________________________ 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 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.commailto:aschwanden@lmsal.com _______________________________________ ____________________________________