Convective core mixing: A metallicity dependence?

The main purpose of this paper is to investigate the possible existence of a metallicity dependence of the overshooting from main sequence star turbulent cores. We focus on objects with masses in the range similar to2.5 M-.- similar to25 M-.. Evolutionary time scale ratios are compared with star number ratios on the main sequence. Star populations are synthesized using grids of evolutionary tracks computed with various overshooting amounts. Observational material is provided by the large and homogeneous photometric database of the OGLE 2 project for the Magellanic clouds. Attention is paid to the study of uncertainties: distance modulus, intergalactic and interstellar reddening, IMF slope and average binarity rate. Rotation and the chemical composition gradient are also considered. The result for the overshooting distance is l(over)(SMC) = 0.40(+0.12)(-0.06) H-p (Z(0) = 0.004) and l(over)(LMC) = 0.10(-0.10)(+0.17) H-p (Z(0) = 0.008) suggesting a possible dependence of the extent of the mixed central regions with metallicity within the considered mass range. Unfortunately it is not yet possible to fully disentangle the effects of mass and chemical composition.