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<TITLE>RE: [Loops] summaries on nanoflare debates in "coronalloopworkshops"</TITLE>
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<P><FONT SIZE=2>Hi Jim,<BR>
<BR>
I was talking about the waves with observed (relatively low, > 2 min) periods and low amplitudes, which are not likely to<BR>
energetically contribute to heating,<BR>
but are excellent diagnostics tools. They have already been used for this purpose and gave results which indicate the presence of fine (sub-resolution) structuring.<BR>
<BR>
Concerning triggering of reconnection events by waves: it can be achieved by waves of relatively low amplitude and this option, I think,<BR>
needs detailed attention.<BR>
<BR>
Cheers,<BR>
<BR>
Valery<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: loops-bounces@mithra.physics.montana.edu on behalf of Klimchuk, James A. (GSFC-6710)<BR>
Sent: Mon 09/03/2009 17:02<BR>
To: A mailing list for scientists involved in the observation andmodeling ofsolar loop structures; A mailing list for scientists involved in the observation and modelingofsolar loop structures<BR>
Subject: Re: [Loops] summaries on nanoflare debates in "coronalloopworkshops"<BR>
<BR>
Valery and Robert,<BR>
<BR>
<BR>
<BR>
Thanks for bringing up waves. I have two quick points.<BR>
<BR>
<BR>
<BR>
1. The internal plasma structure of a loop (multi-stranded or not) is<BR>
determined by the heating and cannot be decoupled from the wave<BR>
dissipation (unless the wave is energetically insignificant). See<BR>
Section 4.3 of the attached.<BR>
<BR>
<BR>
<BR>
2. There may be different opinions of what is meant by "nanoflare."<BR>
Some people define it to be an identifiable point-like brightening that<BR>
probably occurs in a tiny bipole. Most loops modelers define it to be<BR>
an impulsive energy release in a long and unresolved magnetic strand.<BR>
It cannot be directly observed. With this definition, even resonant<BR>
wave absorption produces nanoflare heating (also explained in Sections<BR>
4.3 and 4.2). I'm very curious about David Berghmans' talk and have my<BR>
doubts about the conclusions!<BR>
<BR>
<BR>
<BR>
Cheers,<BR>
<BR>
Jim<BR>
<BR>
<BR>
<BR>
________________________________<BR>
<BR>
From: loops-bounces@solar.physics.montana.edu<BR>
[<A HREF="mailto:loops-bounces@solar.physics.montana.edu">mailto:loops-bounces@solar.physics.montana.edu</A>] On Behalf Of<BR>
Nakariakov, Valery<BR>
Sent: Saturday, March 07, 2009 9:02 AM<BR>
To: A mailing list for scientists involved in the observation and<BR>
modeling ofsolar loop structures; A mailing list for scientists involved<BR>
in the observation and modelingofsolar loop structures<BR>
Subject: Re: [Loops] summaries on nanoflare debates in<BR>
"coronalloopworkshops"<BR>
<BR>
<BR>
<BR>
Hi Robertus, hi all,<BR>
<BR>
>however, both hinode and very recent rosa observations have shown the<BR>
omnipotent presence of mhd waves ... that have the necessary poyting<BR>
flux to heat the lower<BR>
atmosphere or corona. so, it is not just reconnection!<BR>
<BR>
There are two important aspects, in my opinion:<BR>
(a) even if the Poynting flux is sufficient, there also should be<BR>
sufficiently effective mechanisms for the wave energy dissipation at a<BR>
reasonable height. The efficiency of both phase mixing and RA is<BR>
determined by the steepness of the transverse structuring of the<BR>
waveguiding plasma structures.<BR>
<BR>
Structuring is definitely an unknown parameter, as you've pointed out:<BR>
>if (IF) we want to get closer to loop fine structure<BR>
(multi-thread vs whatever) or uncover the operating heating function, a<BR>
very promising and currently already available way is of the one by<BR>
magneto-seismology.<BR>
<BR>
I agree. As I have mentioned in this forum before, there are several<BR>
coronal seismological indications of the subresolution structuring of<BR>
the corona. But, what is important is not only the spatial scale of<BR>
structuring, but also the gradients of the plasma parameters.<BR>
<BR>
(b) The amplitudes of the observed transverse waves are sufficiently<BR>
high to produce a significant change of the magnetic field in the<BR>
vicinity of the potential reconnection<BR>
sites. Hence, the waves can effectively contribute to reconnection, and<BR>
then the separation of "wave-based" and "reconnection-based" mechanisms<BR>
for heating seems to be a bit too artificial.<BR>
<BR>
All the best,<BR>
<BR>
Valery<BR>
<BR>
<BR>
<BR>
<BR>
</FONT>
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