Lithium abundances in open clusters provide an effective way of probing mixing processes in the interior of solar-type stars and convection is not the only mixing mechanism at work .
To understand which mixing mechanisms are occurring in low-mass stars , we test non-standard models , which were calibrated using the Sun , with observations of three open clusters of different ages , the Hyades , NGC 752 , and M67 .
We collected all available data , and for the open cluster NGC 752 , we redetermine the equivalent widths and the lithium abundances .
Two sets of evolutionary models were computed , one grid of only standard models with microscopic diffusion and one grid with rotation-induced mixing , at metallicity [ Fe/H ] = 0.13 , 0.0 , and 0.01 dex , respectively , using the Toulouse-Geneva evolution code .
We compare observations with models in a color-magnitude diagram for each cluster to infer a cluster age and a stellar mass for each cluster member .
Then , for each cluster we analyze the lithium abundance of each star as a function of mass .
The data for the open clusters Hyades , NGC 752 , and M67 , are compatible with lithium abundance being a function of both age and mass for stars in these clusters .
Our models with meridional circulation qualitatively reproduce the general trend of lithium abundance evolution as a function of stellar mass in all three clusters .
This study points out the importance of mass dependence in the evolution of lithium abundance as a function of age .
Comparison between models with and without rotation-induced mixing shows that the inclusion of meridional circulation is essential to account for lithium depletion in low-mass stars .
However , our results suggest that other mechanisms should be included to explain the Li-dip and the lithium dispersion in low-mass stars .