Cool Stars 14 - Submitted Abstract # 76 This version created on 05 October 2006 Models of alpha Centauri A and B with and without seismic constraints: the time dependence of the mixing-length parameter Mutlu Yildiz, Ege University The alpha Cen binary system is one of the well known stellar systems with very accurate observational constraints to structure of its component stars. In addition to the classical non-seismic constraints, we have also seismic constraints for the interior models of alpha Cen A and B. While we obtain 8.9 Gyrs for the age of the system for non-seismic constraints, the seismic constraints imply that it is about 5.6-5.9 Gyrs. The alpha Cen binary system with its solar type components is also very suitable for testing the stellar mass dependence of the mixing-length parameter for convection derived from the binaries of Hyades. We can interpret this mass dependence as it is valid near the zero-age-main-sequence and we will be observing how it will be as stars evolve. The values of the mixing-length parameter for alpha Cen A and B are 2.10 and 1.90 for the non-seismic constraints. If we employ the seismic constraints together with the non-seismic constraints (except the luminosity of alpha Cen B), we obtain 1.64 and 1.91 for alpha Cen A and B, respectively. By taking care of these two different aspects for the mixing-length parameter, we derive two expressions for its time dependence which are also compatible with the mass dependence of the mixing-length parameter derived from the Hyades stars. ----------------------------------