Evolutionary tracks of massive star in the Hertzsprung-Russell diagram. Effects of rotation are included in the thick-lined tracks, using an initial equatorial rotation velocity of 200 km/s. Different colors correspond to different initial masses, as indicated by the labels (initial mass in solar masses). The tracks end on the Zero Age Main Sequence (hydrogen ignition) and are computed until the cental iron core starts to colapse. Find more details in our paper in Astrophysical Journal Vol. 544, pp. 1016-1035 (Dec.1, 2000), or in Alexander Heger's PhD Thesis here .