AAS 200th meeting, Albuquerque, NM, June 2002
Session 2. Coronal Plasmas
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[2.08] Multi-Thermal Analysis of SOHO-CDS Coronal Loops

P.J. Hubbard, J.T. Schmelz (University of Memphis)

Our analysis of the 20 April 1998 SOHO-CDS spectral line data for a loop on the solar limb showed that the plasma was multi-thermal, both along the length of the loop as well as along the line of sight. We have now completed analysis for two additional loops and find similar results, which are in stark contrast to those obtained recently by several groups who used EIT and TRACE data. They used a standard narrowband filter ratio technique to obtain temperature maps that assumes, a priori, that the plasma observed along the line of sight is isothermal. Perhaps both types of loops exist in the corona; or perhaps the isothermal loops are an artifact of the somewhat simplistic filter ratio temperature analysis; or perhaps the multi-thermal loops are the result of contamination from background structures of different temperatures in the same field of view. We present here the first step in an attempt to reconcile these seemingly disparate results. We have taken the differential emission measure curves generated for the CDS 20 April 1998 loop, and folded these temperature distributions through the Al.1 and AlMg response functions of SXT. This produced predicted values (in DN/sec) for Al.1 and AlMg filters of SXT at each pixel. We then calculated the temperature from these predictions using the normal SXT filter ratio method, and compared these temperatures with those obtained from the SXT observations. We hope to expand this project in the future to include SOHO-EIT and TRACE observations. 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.