[Loops] EM loci

[Giulio Del Zanna]

A quick reply to Piet and Joan.


Piet: 
Within CHIANTI, we keep a few tabulated ion abundances, so if you plot the
I/G(T) for a few ions and different tables, you can see how ion abundances
have changed over the years. That does not mean it gives you an indication
of an uncertainty. The last ones should be accurate, however if you deal
with high-Ne (middle, low-TR) you also have other effects.

Joan:
I was careful in what I wrote. The EM Loci method has been used a lot,
but I had not seen a paper using it to look at the warm (about 1 MK) loops.
I might have missed it of course (see reply below).
I was aware of the  SMM FCS results but they concerned the hot core loops.
The spatial resolution was very limited and the core loops are so
'unresolved' that I do not think that anyone could actually resolve a loop.
With CDS and EIS at least some 'fat' warm loops are resolvable towards their
footpoints against the unresolved background/foreground emission.


Giulio

*************************************************************

On Tue, 28 Sep 2010, Joan T Schmelz (jschmelz) wrote:

> Giulio,
>
> Careful! Before you claim to have re-introduced the EM Loci method, here are just a couple counter-examples:
>
> http://adsabs.harvard.edu/abs/1994ApJ...429..909W

The above I think just shows what was known from e.g. Rosner et al. 1978, i.e. 
that the hot core loops are 'nearly isothermal' at 3-4 MK.


> http://adsabs.harvard.edu/abs/1996ApJ...473..519S

Had similar results in terms of temperature of the hot loops, again from the 
excellent SMM/FCS spectra of active regions.

> We've been using it for a long time. I think some good recent examples are
>
> http://adsabs.harvard.edu/abs/2008ApJ...686L.131W

When I wrote that my CDS results so far have been confirmed
by Hinode/EIS I had in mind this nice paper from Harry et al. 
and that one from  Tripathi et al.


> and
>
> http://adsabs.harvard.edu/abs/2009ApJ...704..863S

This again is on the hot loops.


> Regards,
> Joan
>