H II Regions and Protosolar Abundances in Galactic Chemical Evolution

we present chemical evolution models of the galactic disk with different z dependent yields. we find that a moderate mass loss rate for massive stars of solar metallicity produces an excellent fit to the observed c/h and c/o gradients of the galactic disk. the best model also fits: the h, he, c, and o abundances derived from recombination lines of m17, the protosolar abundances, and the c/o-o/h, c/fe-fe/h, and o/fe-fe/h relations derived from solar vicinity stars. the agreement of the model with the protosolar abundances implies that the sun originated at a galactocentric distance similar to the one it has now. our model for r = 3 kpc implies that a fraction of the stars in the direction of the bulge formed in the inner disc. we obtain a good agreement between our model and the c/o versus o/h relationship derived from extragalactic h ii regions in spiral galaxies.