Luminosity vs. effective temperature of the stars. The solid line shows the evolutionary track for 1 M_⊙, the dash-dotted line for 0.99 M_⊙, and the dash-triple-dotted line for 0.98 M_⊙ with Z = 0.0185. The dashed line denotes the evolutionary track for 1.11 M_⊙ and Z = 0.0196. The asterisk at the evolutionary track marks a time step of 1 Gyr, and the first step is labelled with the age.