The rotation-lithium depletion correlation in the beta Pictoris association and the LDB age determination

Context. Evidence exists in the 125-Myr Pleiades cluster, and morerecently in the 5-Myr NGC2264 cluster, to show that rotation plays a keyrole in lithium (Li) depletion processes among low-mass stars. Fastrotators appear to be less Li-depleted than equal-mass slow rotators.Aims. We intend to explore the existence of a Li depletion-rotationconnection among the beta Pictoris members at an age of about 24 Myr,and to use this correlation either to confirm or to improve ageestimates based on the lithium depletion boundary (LDB) modeling.Methods. We photometrically monitored all the known members of the betaPictoris association with at least one lithium equivalent width (Li EW)measurement from the literature.Results. We measured the rotation periods of 30 members for the firsttime and retrieved the rotation periods for another 36 members from theliterature, building a catalogue of 66 members with a measured rotationperiod and Li EW.Conclusions. We find that in the 0.3 < M < 0.8 M circle plus range,there is a strong correlation between rotation and Li EW. For highermass stars, no significant correlation is found. For very low-mass starsin the Li depletion onset, at about 0.1 M circle plus, there are too fewdata to infer a significant correlation. The observed Li EWs arecompared with those predicted by the Dartmouth stellar evolutionarymodels that incorporate the effects of magnetic fields. Afterdecorrelating the Li EW from the rotation period, we find that the hotside of the LDB is well fitted by Li EW values that correspond to an ageof 25 +/- 3 Myr, which is in good agreement with independent estimatesfrom the literature.