[Loops] EM loci

[Scott W. McIntosh]

Can I point out a paper to the list: 

http://adsabs.harvard.edu/abs/2010ApJ...708.1238J

This paper encapsulates the problem in a concise form. I could point out a couple more, but those are nearly 10 years old now, wow how time flies. I have drawn my line in the sand with emission measures as a practical diagnostic - once we have a DEM/EM, etc what can we do with it? As far as I can tell there are only a few papers in the literature that deal with that particular issue in a real sense and those are from further back in the 80s [look for papers by Carole Jordan].

I am all for learning something about the solar plasma from a zeroth order approach. However, no EM/DEM/Line Ratio estimation deals with the real time-varying corona (or outer solar atmosphere as we need to deal with a intrinsically coupled system). By definition, these diagnostic deal with equilibrium processes and thermal populations - I am not entirely sure that we have that in place and if we do is, is that the process doing the "heavy lifting" or just the after effect procing the apparent stationary state.....there is strong evidence of non-thermal processes affecting the chromospheric, TR and coronal plasmas in the very same spectra from which such diagnostics are derived [probably even worse for broadband EUV imagers].

Sorry, to be a bummer!

-S. 

**---------------------------------------------------------------------------------------------**
                          		Dr. Scott W. McIntosh

National Center for Atmospheric Research        Phone:  303 497 1544  
 (Room 3624)  High Altitude Observatory           Fax:    303 497 1589
     3080 Center Green Drive - CG1             	    email: mscott at ucar.edu
         	Boulder, CO 80301             
         
         			http://people.hao.ucar.edu/mscott/







On Sep 23, 2010, at 7:25 AM, Klimchuk, James A. (GSFC-6710) wrote:

> Friends,
>  
>      The EM loci technique is frequently used to access whether a plasma is isothermal.  The attached paper addresses the uncertainty in this technique and proposes a way to determine the range of thermal distribution widths that are consistent with a set of emission line data.
>  
> Cheers,
> 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://science.gsfc.nasa.gov/671/staff/bios/cs/James_Klimchuk_ssi.html
>  
> No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, American Astronomical Society, International Astronomical Union).
>  
> ********************************************************************************
>  
>  
> <em_loci.pdf>_______________________________________________
> Loops mailing list
> Loops at solar.physics.montana.edu
> https://mithra.physics.montana.edu/mailman/listinfo/loops

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mithra.physics.montana.edu/pipermail/loops/attachments/20100923/0e23c218/attachment.html>