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D.A. Medlin, J.T. Schmelz, J.E. Beene (University of Memphis)
If one is to study solar active regions and the processes that drive them, one must accurately describe the temperature distributions and the elemental abundances of the emitting plasma. The best way to determine these vital parameters is with multi-thermal analysis techniques, which do not have as many initial assumptions as their isothermal counterparts. The accuracy of these emission measure distributions depends on spectroscopic observations of emitting ions that cover a broad temperature range.
The Solar EUV Rocket Telescope and Spectrograph (SERTS) is well suited for studying multi-thermal coronal structures. It provides observations of numerous emission lines with excellent spectral resolution. Observations taken with the Soft X-ray Telescope (SXT) were combined with data from SERTS in order to constrain the high-temperature end of the multi-thermal distribution. Three active regions (AR 7563, AR 7870, and AR 8108) were chosen for this investigation. All three regions were observed simultaneously with both instruments. We generated a differential emission measure (DEM) curve for each region using the SERTS iron lines and the SXT data. Therefore, we were interested to see the results for the other (non-iron) lines when the same DEM curve was used to model the plasma. Initially the hybrid abundance values were used for the elements in each separate SERTS data set. Then these abundances were adjusted so that the predicted intensities agreed with the observed as closely as possible. The results show how the elemental abundances vary from one region to the next. Solar physics research at the University of Memphis is supported by NASA grant NAG5-9783.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.