[Loops] loops and thermal nonequilibrium

[Hugh Hudson]

Dear Jim

I have some comments. It looks like a nice piece of work, but as usual  
the conclusion that only nanoflares can help is hopelessly quixotic.  
You set up a strawman competing mechanism (why call it "thermal  
nonequilibrium" when the one-syllable alternative "flow" works as  
well?) and reject it on the basis of time scales. Who knows about the  
time scales of the driver of the flows?

The model itself seems highly questionable. I had cited its  
predecessor in trying to explain the "chewy nougat" observation of X- 
rays from prominences (http://adsabs.harvard.edu/abs/1999ApJ...513L.. 
83H) but realized later on that the model has a very artificial low- 
temperature boundary and is thus not compelling. It is surprising to  
me that a decade later this has not changed, especially since it is  
just this boundary region in which the heating may be taking place.

To be perfectly clear about nanoflares: I do not think that there is  
any convincing observational evidence that they exist. It is a purely  
theoretical construct.

Cheers

Hugh

p.s. at the Hinode meeting just concluded, a nice poster by Helen  
Mason made it very clear that EIS spectra emphatically do not agree  
with the various XRT suggestions of a high-temperature component in  
the loop DEM. The discrepancy is an order of magnitude.

On 4 Dec 2009, at 14:04, 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 at nasa.gov
> Home page:  http://hsd.gsfc.nasa.gov/staff/bios/cs/James_Klimchuk.html
>
> ********************************************************************************
>
> <klimchuk_submitted.pdf>
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