Fig. 8. Present day abundance gradients in the Milky Way disk: summary of models vs. observations. Model results are shown by open symbols (asterisks , for the WW95 yields, connected by a solid curve , and pentagons for the M92 yields, only for C, N and O). Observations (Table 1 for references) are shown by filled symbols . Notice the large discrepancy between the carbon gradients observed in B-stars and HII regions, respectively. An average gradient of -0.070.02 dex kpc^-1 is compatible with most of the data and the model results. Most of the observed abundance gradients are rather well reproduced by the model, but the case of Al is problematic (see text).