Markus et al.,
It is unambiguous that there is a lot of dynamic activity going on in the transition region. However:
. . . a significant fraction of the Sun's magnetic flux closes at low heights (several Mm), so it is unclear how much of this activity is related to what we see in the corona.
. . . my impression of SOT magnetic field measurements is that active region plage (where many active region loops are rooted) is unipolar. It is hard to see how small-scale reconnection in the transition region could be important here. I could be wrong about this! I'm sure that an SOT person could provide a more definitive answer.
Best wishes,
Harry
// --------------------------------------------------------------------- // Harry P. Warren phone : 202-404-1453 // Naval Research Laboratory fax : 202-404-7997 // Code 7673HW email : hwarren@nrl.navy.mil // Washington, DC 20375 www : http://tcrb.nrl.navy.mil/~hwarren // ---------------------------------------------------------------------
From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.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 modeling of 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 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.com _______________________________________ ____________________________________