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R. Mewe (1), C.J. Schrijver (1), J.S. Kaastra (2), F.J.M. Alkemade (1), and B.M. Haisch (3)
1) Laboratory for Space Research (SRON), Utrecht, the
Netherlands
2) Laboratory for Space Research (SRON),
Leiden, the Netherlands
3) Lockheed Palo Alto Research
Laboratory, Palo Alto, California, U.S.A.
The analysis of the EXOSAT Transmission Grating Spectrometer (TGS) (10-200 Å) spectra of two RS-CVn systems, Capella andSigma^2 CrB, as presented by Lemen et al. (1989), showed the coronae of these stars to be dominated by emission from two temperature intervals, one around solar coronal temperatures, the other in excess of 10 MK. The lack of strong emission from plasma at < MK was shown to be consistent with models of quasi-static loops that were narrower at the footpoints than at the tops (Schrijver et al. 1989). Recent high-resolution observations by YOHKOH suggest, however, that the solar coronal loops do not have such a strongly changing cross section with height, at least for plasma above 1 MK. We observed other cool stars (the RS CVn's Xi UMa, Sigma Gem, and the single MS star Chi-1 Ori) with the EUVE spectrometers to study the temperature structure of stellar coronae and the geometry of coronal loops. Here we report preliminary results of a differential emission measure analysis.
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