RADIO AND EXTREME-ULTRAVIOLET OBSERVATIONS OF CF TUCANAE

We present contemporaneous EUV and radio observations obtained for the totally eclipsing chromospherically active RS CVn-type binary CF Tuca nae, Observations were made with the ATNF Compact Array at 6 and 3.6 c m over one complete orbital cycle of the system, and with the EUVE Dee p Survey/Spectrometer telescope over five orbital cycles, We obtained a strong detection of the source (1.9 mJy at 6 cm and 1.1 mJy at 3.6 c m) in the radio. Both EUV and radio flux levels appear to show a clear modulation at the orbital period with a maximum at phase 0.5 which in dicates the existence of an intra-binary region of activity. This has important consequences for the details of coronal formation and field interaction in active close binary stars, We interpret the EUV emissio n as an isotropically radiating thermal source; on the other hand, the radio emission shows evidence of intrinsic gyromagnetic directivity. We also demonstrate that contemporaneous EUV and radio observations ar e not sufficient to determine the characteristics of the gyro-emission electron population.