The optical gravitational lensing experiment. Variable stars in globular clusters - II. Fields 5139D-F in ω Centauri

Three elds covering the central part of the globular cluster! Cen were surveyed in a search for variable stars. We present V -band light curves for 39 periodic variables: 24 SX Phe stars, 7 contact binaries, 5 detached or semi-detached binaries, and 3 likely spotted variables (FK Com or RS CVn type stars). Only 2 of these variables were previously known. All SX Phe stars and all contact binaries from our sample belong to blue stragglers. Observed properties of these stars are consistent with their cluster membership. Of particular interest is detection of two well detached binaries with periods P =1.50 day and P =2.47 day. Further study of these two binaries can provide direct information about properties of turno stars in ! Cen. An incomplete light curve of a Mira variable known as V 2w as obtained. We present V vs. V I color-magnitude diagrams for the monitored part of the cluster.