THE HELIUM-TO-HYDROGEN RATIO OF THE UV-BRIGHT STAR BARNARD-29 OF MESSIER-13

Barnard 29 is the most luminous W-bright star of the globular cluster Messier 13. Comparison of its reddening corrected optical region spect rophotometry and IUE low dispersion fluxes and its H gamma profile wit h the predictions of metal-poor model atmospheres having the metallici ty of M 13 indicated T-eff = 20 250 K, log g = 3.15. Observations of H e I lambda 4026 taken with echelle spectrograph of the Multi-Mirror te lescope using a Reticon detector show that He/H = 0.055 +/- 0.020. Som e astrophysical implications of this result are discussed.