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<title>RE: [Loops] summaries on nanoflare debates in
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Valery and Robert,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> Thanks for bringing up
waves. I have two quick points.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>1. The internal plasma structure of
a loop (multi-stranded or not) is determined by the heating and cannot be
decoupled from the wave dissipation (unless the wave is energetically insignificant).
See Section 4.3 of the attached.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>2. There may be different opinions
of what is meant by “nanoflare.” Some people define it to be
an identifiable point-like brightening that probably occurs in a tiny bipole. Most
loops modelers define it to be an impulsive energy release in a long and
unresolved magnetic strand. It cannot be directly observed. With
this definition, even resonant wave absorption produces nanoflare heating (also
explained in Sections 4.3 and 4.2). I’m very curious about David
Berghmans’ talk and have my doubts about the conclusions!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Cheers,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Jim<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
loops-bounces@solar.physics.montana.edu [mailto:loops-bounces@solar.physics.montana.edu]
<b><span style='font-weight:bold'>On Behalf Of </span></b>Nakariakov, Valery<br>
<b><span style='font-weight:bold'>Sent:</span></b> Saturday, March 07, 2009
9:02 AM<br>
<b><span style='font-weight:bold'>To:</span></b> A mailing list for scientists
involved in the observation and modeling ofsolar loop structures; A mailing
list for scientists involved in the observation and modelingofsolar loop
structures<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Loops] summaries on
nanoflare debates in "coronalloopworkshops"</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p><font size=2 face="Times New Roman"><span style='font-size:10.0pt'>Hi
Robertus, hi all,<br>
<br>
>however, both hinode and very recent <st1:place w:st="on">rosa</st1:place>
observations have shown the<br>
omnipotent presence of mhd waves ... that have the necessary poyting 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 sufficiently
effective mechanisms for the wave energy dissipation at a reasonable height.
The efficiency of both phase mixing and RA is determined by the steepness of
the transverse structuring of the 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 coronal
seismological indications of the subresolution structuring of the corona. But,
what is important is not only the spatial scale of structuring, but also the
gradients of the plasma parameters.<br>
<br>
(b) The amplitudes of the observed transverse waves are sufficiently high to
produce a significant change of the magnetic field in the vicinity of the
potential reconnection<br>
sites. Hence, the waves can effectively contribute to reconnection, and then
the separation of "wave-based" and "reconnection-based"
mechanisms for heating seems to be a bit too artificial.<br>
<br>
All the best,<br>
<br>
Valery<br>
<br>
</span></font> <o:p></o:p></p>
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