Stellar models with microscopic diffusion and rotational mixing. 2: Application to open clusters

Stellar models with masses ranging from 0.5 to $1.3~M_\odot$ were constructed in order to compare to young cluster observations of Li and of rotation velocities. The amount of Li depletion in cool stars is sensitive to the amount of overshoot at the base of the surface convection zone, and the exact metallicity of the models. Even when this uncertainty is taken into account, the Li observations are a severe constraint for the models and rule out standard models, and pure diffusion models. Stellar models which include diffusion and rotational mixing in the radiative regions of stars are able to simultaneously match the Li abundances observed in the Pleiades, UMaG, Hyades, Praesepe, NGC 752 and M67. They also match the observed rotation periods in the Hyades. However, these models are unable to simultaneously explain the presence of the rapidly rotating late G and K stars in the Pleiades and the absence of rapidly rotating late F and early G stars.Comment: 15 pages, uuencoded postscript, also available by anonymous ftp to ftp.cita.utoronto.ca in: /cita/brian/papers/cluster.ps submitted to ApJ, CITA-94-3