Résumé
Stellar evolutionary tracks have been computed for masses from 0.5 to 1.0 M., Y = 0.2352, and Z = 1.69 X 10(-4) ([Fe/H] = -2.31, [alpha/Fe] = 0.3) in which, for the first time for Population 11 stars, both gravitational settling and radiative accelerations have been taken into account. These calculations, which imply a 10-12% reduction in age at a given turnoff luminosity compared with the predictions of non-diffusive models, are able to satisfy Fe and Li.abundance constraints rather well (if turbulent mixing is invoked below the boundary of the convective envelope). Moreover, a 13.5 Gyr isochrone provides a good match to the color-magnitude diagram (CMD) of M92 when the cluster distance is set by the local field subgiant HD 140283 (sigma(pi)/pi = 0.06 from Hipparcos), which has a similar metallicity and reddening.