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(circle dot) were constructed for comparison with young cluster observations of Li and o f rotation velocities. The amount of Li depletion in cool stars is sen sitive to the amount of overshoot at the base of the surface convectio n zone, and the exact metallicity of the models. Even when this uncert ainty is taken into account, the Li observations are a severe constrai nt for the models and rule out standard models and pure diffusion mode ls. Stellar models which include diffusion and rotational mixing in th e radiative regions of stars are able to simultaneously match the Li a bundances observed in the Pleiades, the UMa Group, the Hyades, Praesep e, 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 Pleiad es and the absence of rapidly rotating late F and early G stars.