Thermal structure of solar coronal loops and implications for physical models of coronae
We analyze EUV spectra of three active region loops observed above the solar limb with the SO55 spectrometer on Skylab. The lengths, peak temperatures, and pressures of the loop are typical of the x-ray coronal loops to which static models have been applied. We find that the physical parameters of the coronal loop plasma derived from our EUV spectra and raster pictures are not well represented by the static models. Although the loops also contain a significant quantity of cool plasma, we find no physical reason to differentiate them from other active region loops of similar length, pressure, and temperature. Several line ratios in the loop spectrum indicate departures from ionization equilibrium caused by rapid cooling. We discuss the source of this cooling material with reference to several models of loop dynamics. These results suggest that analysis of UV and x-ray spectra of other stars in terms of the static loop models is questionable.
- Research Organization:
- Harvard-Smithsonian Center for Astrophysics
- OSTI ID:
- 5234653
- Journal Information:
- Astrophys. J.; (United States), Vol. 253:1
- Country of Publication:
- United States
- Language:
- English
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