[Loops] More Hinode AR loops - Ugarte-Urra et al. 2009, ApJ

[Markus J. Aschwanden]

Dear Ignacio,

Thanks for the preprint. I guess this is the same work we had an  
interesting
discussion at the Napa meeting back in December. The results are  
intriguing,
especially the dependence of the loop lifetimes on the temperature.  
However,
you probably realize (better than we all) how many loops intersect in  
the
fore- and background of the line-of-sight where you choose a box and  
plot
a lightcurve to derive the lifetime. I have the impression that most  
lightcurves
contain emission from multiple loops, but I admit that it is very  
difficult to
disentangle them. It would be interesting if we could isolate  
individual loops
by proper geometric (cross-sectional+background) modeling in all  
filters to
see if your preliminary results hold up.
Keep us posted about further progress!

Cheers,
Markus



On Jan 9, 2009, at 5:54 AM, Ignacio Ugarte Urra wrote:

> Hi all,
>
> Just wanted to let you know about a paper on EIS/XRT observations of
> coronal loops just accepted by ApJ.
>
> http://arxiv.org/abs/0901.1075
>
> Title: "Active region transition region loop populations and their
> relationship to the corona"
> Authors: Ignacio Ugarte-Urra, Harry P. Warren and David H. Brooks
>
> Abstract:
> The relationships among coronal loop structures at different
> temperatures is not settled. Previous studies have suggested that
> coronal loops in the core of an active region are not seen cooling
> through lower temperatures and therefore are steadily heated. If loops
> were cooling, the transition region would be an ideal temperature  
> regime
> to look for a signature of their evolution. The Extreme-ultraviolet
> Imaging Spectrometer (EIS) on Hinode provides monochromatic images of
> the solar transition region and corona at an unprecedented cadence and
> spatial resolution, making it an ideal instrument to shed light on  
> this
> issue. Analysis of observations of active region 10978 taken in 2007
> December 8 -- 19 indicates that there are two dominant loop  
> populations
> in the active region: core multi-temperature loops that undergo a
> continuous process of heating and cooling in the full observed
> temperature range 0.4-2.5 MK and even higher as shown by the X-Ray
> Telescope (XRT); and peripheral loops which evolve mostly in the
> temperature range 0.4-1.3 MK. Loops at transition region temperatures
> can reach heights of 150 Mm in the corona above the limb and develop
> downflows with velocities in the range of 39-105 km/s.
>
> Best,
> Ignacio
> -- 
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> ~ Ignacio Ugarte-Urra ~
>   Naval Research Laboratory. Code 7673U.
>   4555 Overlook Ave SW. Washington, DC 20375
>   Contractor. Spain.
>   phone: (+1) 202 404 1779
>   email: iugarte at ssd5.nrl.navy.mil
>   http:  http://tcrb.nrl.navy.mil/~iuu
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
>
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____________________________________________
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 at lmsal.com
_______________________________________
____________________________________



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