CANADA-FRANCE-HAWAII-TELESCOPE OBSERVATIONS OF GLOBULAR-CLUSTER CORES - BLUE STRAGGLER STARS IN M3 (NGC-5272, GC-1339+286)

We have obtained a complete inventory of stars brighter than the main-sequence turnoff inside 5 core radii (r(c)) in M3, which reveals a blue straggler star (BSS) population in the central regions of this intermediate-density cluster. The data are derived from CCD frames with FWHM < 0.6'' obtained with HRCam at the Canada-France-Hawaii Telescope. In the 2' x 2' region surveyed, the BSSs are marginally more centrally concentrated than giants in the same V-magnitude range. The specific frequency of BSSs inside 5 r(c) is approximately 2.8 and approximately 3.9 times lower than that measured in the outskirts of M3 and in the low-density cluster NGC 5053, respectively. This result suggests that the production of BSSs through direct stellar collisions or the formation of hard binaries is not significant for central stellar densities up to that of the core of M3. Rather, we may be seeing the effects of a higher destruction rate for primordial binaries in the core of M3 compared with its outer regions, or compared with the lower density cluster NGC 5053.