The evolution of a 25 M-circle dot star from the main sequence up to the onset of the iron core collapse

We present the evolution of a 25 M. star model having solar chemical compos ition from the premain-sequence phase up to the onset of the iron core coll apse. This evolution has been obtained with the latest version (release 4.0 ) of our hydrostatic evolutionary code FRANEC, and hence it is totally homo geneous with all of our stellar evolutions concerning low and intermediate- mass stars. A network including 149 nuclear species has been fully coupled to the equations describing the temporal variations of the physical quantit ies. No quasi-nuclear statistical equilibrium approximation has been adopte d up to 4 x 10(9) K. All of the evolutionary properties of the stellar mode l are discussed in detail. Whenever possible, comparisons with similar evol utions available in the literature have been performed. An iron core mass s maller than the values recently quoted in the literature for the same mass and solar chemical composition has been obtained (M-Fe = 1.513 M.).