RADIAL VELOCITIES OF STARS IN M 12 (NGC 6218) AND M 56 (NGC 6779) ANDUV-BRIGHT STARS IN GLOBULAR CLUSTERS.

Radial velocities of 46 stars in the fields of the globular clusters M 12 (C 1644-018) and M56 (C 1914+300) show that 23 of the stars are cluster members. When these new measurements are combined with all previous ones, the improved cluster velocities are -41.3 ± 1.5 and -134.0 ± 2.7 km s-1, respectively. Six of the observed stars are cluster UV-bright stars. A color-magnitude diagram is constructed for all known UV-bright stars in 29 globular clusters. This composite diagram suggests that UV-bright stars are present in sufficient numbers that they will contribute appreciably to the integrated ultraviolet light of old, metal-poor stellar populations. Although our figure is an improvement over earlier diagrams, it is still seriously incomplete due to selection effects.