THE LI DIP - A PROBE OF ANGULAR-MOMENTUM TRANSPORT IN LOW-MASS STARS

We use the measures of Li and rotational velocities in F Hyades stars to assess the role of the wind-driven meridian circulation and of shea r turbulence in the transport of angular momentum in stars of differen t masses. Our models include both element segregation and rotation-ind uced mixing, and we treat simultaneously the transport of matter and a ngular momentum as described by Zahn (1992) and Maeder (1995). We show that the hot side of the Li dip in the Hyades is well explained withi n this framework, which was also successfully used to reproduce the C and N anomalies in B type stars (Talon et al. 1997). On the cool side of the dip, another mechanism must participate in the transport of ang ular momentum; its efficiency is linked to the depth of the surface co nvection zone. That mechanism should also be responsible for the Sun's flat rotation profile.