[ITAL]Hubble Space Telescope[/ITAL] Detection of a Quiescent Low-Mass X-Ray Binary Companion in 47 Tucanae

We present the results of a search for optical counterparts to the twoquiescent low mass X-ray binaries (X5 and X7) in the globular cluster 47Tucanae, using high quality Chandra and HST images. A faint blue (V=21.7;U-V=0.9) star within 0.03" of the eclipsing system X5 shows variability on bothshort and long timescales, and is the counterpart of the X-ray source. Thecolors and variability of this object are consistent with the combination oflight from an accretion disk and a red main sequence star (possibly somewhatlarger than a normal MS star with similar luminosity). No evidence is found fora star showing either variability or unusual colors near the position of X7,but a probable chance superposition of a star with V=20.25 limits the depth ofour search.Comment: 4 pages, 3 figures, accepted for ApJ Letter