CF Tucanae: Another Case of Coronal MAD Syndrome?

We present and discuss an extreme-ultraviolet spectrum of the RS CVn binary CF Tuc obtained with the short-wavelength (5W) spectrometer on board the Extreme-Ultraviolet Explorer (EUVE) satellite. In addition to a continuum, only two spectral lines attributed to Fe XXII and Fe XXIII are detected. We show that the EUVE data can be reconciled with a solar abundance plasma only if most of CF Tuc's emission measure is located at temperatures of ≍108 K; alternatively, the plasma must be iron depleted with most of the emission measure located at the peak temperature of the observed line contribution functions. A comparison with previously obtained ROSAT PSPC spectra argues strongly in favor of the latter situation. As a consequence, we are forced to the conclusion that the iron abundance in the corona of CF Tuc is reduced with respect to solar values by factors between 5 and 10. The reasons for the occurrence of this metal abundance deficiency syndrome (MADS) are unclear at present; however, for the specific case of CF Tuc, the extremely low coronal iron abundance might possibly result from an anomalously low photo spheric iron abundance.