HUNDRED THOUSAND DEGREE GAS IN THE VIRGO CLUSTER OF GALAXIES

The physical relationship between low-excitation gas filaments at similar to 10(4) K, seen in optical line emission, and diffuse X-ray emitting coronal gas at similar to 10(7) K in the centers of many galaxy clusters is not understood. It is unclear whether the similar to 10(4) K filaments have cooled and condensed from the ambient hot (similar to 10(7) K) medium or have some other origin such as the infall of cold gas in a merger, or the disturbance of an internal cool reservoir of gas by nuclear activity. Observations of gas at intermediate temperatures (similar to 10(5)-10(6) K) can potentially reveal whether the central massive galaxies are gaining cool gas through condensation or losing it through conductive evaporation and hence identify plausible scenarios for transport processes in galaxy cluster gas. Here we present spectroscopic detection of similar to 10(5) K gas spatially associated with the II alpha filaments in a central cluster galaxy, M87, in the Virgo Cluster. The measured emission-line fluxes from triply ionized carbon (C IV 1549 angstrom) and singly ionized helium (He II 1640 angstrom) are consistent with a model in which thermal conduction determines the interaction between hot and cold phases.