Abstract
We have computed the AY/AZ ratio, the oxygen yield, y(O), and the oxygen to other heavy elements yields ratio, y(O)/y(Z - 0), expected for the solar neighborhood based on recent stellar evolution computations by Maeder and several initial mass flinctions IMFs. We find that the computed values are in good agreement with recent observations only when the IMF derived by Kroupa, Tout, & is used. This agreement is obtained without invoking black hole production by massive stars. The implied mass density in substellar objects for the solar neighborhood, derived from evolution considerations, is smaller than 0.02 M⊙. This result imposes a strong restriction on dynamical models of the solar neighborhood.
