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M.J. Aschwanden (LMSAL)
We focus on the question of elementary plasma structures in the solar corona. The crucial issue under investigation is whether we observe with current high-resolution instrumentation (<1", such as with TRACE) monolithic structures in the corona, i.e., elementary loops or loop threads that are homogeneous in temperature and density in any given cross-section. The search and identification of monolithic structures has fundamental consequences in theory (hydrodynamic modeling, coronal heating function, cross-field diffusion processes) and for the planning and design of future high-resolution EUV and soft X-ray telescopes. The identification of monolithic structures is a necessary prerequisite to apply hydrodynamic models, to determine the time-dependent heating function and cooling processes, and to measure the iron abundance and first-ionization potential (FIP) effect. We analyze a number of loop structures from TRACE triple-filter data (171, 195, 284 A) and present quantitative results about the temperature width of the differential emission measure distribution of the finest resolved coronal loops in the temperature range of T=0.7-2.5 MK. We measure the width range of monolithic loop structures, for which we find upper limits in the range of ~1"-2". A consequence is that loop structures observed with instruments of lower resolution (e.g., with Yohkoh, EIT, CDS) represent composite temperature structures and have to be modeled as such. -We acknowledge support from NASA for TRACE, LWS, and SEC projects.
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.