Plot of the 3.5 to 4.57 Gyr segments of the post-main-sequence tracks (dashed) that were computed for masses from 0.98 to 1.06 ℳ_⊙ (indicated below each track) and the indicated values of Y and [Fe/H]. Open circles represent the T_eff and log    g values at the ages noted just to the right of the y-axis; and hence the solid curves are isochrones for those ages. The filled circle and attached error bars indicate the location of the solar twin, M67-1194.