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H.D. Winter, P.C.H. Martens (Physics Dept., Montana State University)
While line ratio techniques are still the dominant method for making measurements of solar coronal plasma parameters, such as mean electron density and electron temperature, the isothermal approximation on which these methods rely is a poor assumption for many solar features. Differential emission measure (DEM) analysis eliminates the isothermal assumption. The inverse problem that one must solve to generate DEM curves is ill-posed, yielding multiple solutions that fit the observed data. Forward modeling improves the situation but still does not allow one to derive a unique solution that properly models the observed plasma. For DEM curves to have scientific meaning an estimate of the error must be included. We generated DEM curves for several observed solar coronal features and determined the error in each solution from photon statistics. This allows us to use statistical methods to derive the best DEM fit to the data with the smallest number of free parameters. The possible implications for the physics derived from DEM analysis are significant. This work was supported by the MSU NASA/TRACE MO&DA contract.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.