The evolution of the lithium abundances of solar-type stars .7. M34 (NGC 1039) and the role of rotation in lithium depletion

We have used the HiRes spectrograph on the Keek 10 m telescope, and the Hamilton spectrograph on the Shane 3 m telescope to obtain echelle spectra of F, G, and K dwarfs in the open cluster M34 (NGC 1039), which is 250 Myr old. We derive lithium abundances, rotational velocities, and indices of chromospheric emission for these stars. This cluster, intermediate in age between the Pleiades and Hyades, shows a pattern of rotation and Li depletion that is also intermediate between these two clusters. This suggests an evolutionary pattern in which angular momentum loss and Li depletion are tied to one another in solar-type stars. (C) 1997 American Astronomical Society.