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@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@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).
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