Influence of the C-12(alpha,gamma)O-16 reaction rate on the evolution of a15 M-circle dot star

In this paper we present the evolution of various 15M(circle dot) stellar m odels of solar and subsolar chemical composition, calculated using differen t values for the C-12(alpha, gamma)O-16 reaction rate. This process influen ces the evolution of a star because it directly operates during the helium burning and it determines the final abundances of (12)G and O-16 left by th is burning. Since this reaction works in a convective environment an analys is of its influence on the evolution of a star cannot be disentangled by th e behavior of the convective core. Indeed the final C-12 and O-16 abundance s largely depend on a delicate balance between the efficiency of this rate and the treatment of the convective core. We will show some tests which ind icate quantitavely this interplay.