LIMITS ON FAR-ULTRAVIOLET EMISSION FROM WARM GAS IN CLUSTERS OF GALAXIES WITH THE HOPKINS ULTRAVIOLET TELESCOPE

We have searched the far-UV spectra of five clusters of galaxies obser ved with the Hopkins Ultraviolet Telescope (HUT) for emission in the r esonance lines of O vr lambda lambda 1032, 1038 and C N lambda lambda 1548, 1551. We do not detect significant emission from either species in any of the spectra. Lieu et al. have recently proposed a warm [(5-1 0) x 10(5) K] component to the intracluster medium (ICM) to explain ex cess 0.065-0.245 keV flux present in EUVE and ROSAT observations of th e Virgo cluster. If the surface brightness of this warm component foll ows that of the hot, X-ray-emitting gas (i.e., is centrally condensed) , then our upper limit to the O VI surface brightness in M87 is incons istent with the presence of substantial 5 x 10(5) K gas in the center of the Virgo cluster. This inconsistency may be alleviated if the cent ral gas temperature is greater than or similar to 7.5 x 10(5) K. HUT l imits on the 0 VI surface brightness of the four other clusters can pr ovide important constraints on models of their ICM.