EUV EMISSION FROM RS CANUM-VENATICORUM BINARIES

We performed a study of 104 RS CVn systems in the extreme ultraviolet (EUV) using the all-sky survey data obtained by the Extreme Ultraviole t Explorer (EWE). The present sample includes several new RS CVn detec tions; 11 more than in the published EWE catalogs, and 8 more than in the ROSAT Wide Field Camera catalog. The ratio of detections to non-de tections remained constant throughout the sky, implying that our detec tions are not limited by the exposure time but are most likely limited by absorption from the interstellar medium. A general trend of increa sing Lex/B (50-180 Angstrom) flux with decreasing rotational period is clear. The dwarf systems exhibit a leveling-off for the faster rotato rs. In contrast, the evolved systems exhibit no such effect. For the R S CVn systems the losses in the EUV represent a smaller fraction of th e coronal radiative losses, as compared to active late-type dwarfs.