A subject of central importance to astronomers is the chemical evolution of our and other galaxies. What were the elements, besides hydrogen and helium-4, out of which galaxies formed? How did the primordial abundances change during the intervening eons, due to stellar nucleosynthesis? Which types of stars contributed principally to this change? The Principal Investigator (PI) proposes to address these questions with regard to our Galaxy by continuing with his current NSF- supported research. He intends to use high-resolution stellar spectroscopy to obtain abundance data of carbon, oxygen, and nitrogen in young, metal-rich stars (i.e., non-variable supergiants, Cepheid stars, B-type stars on the main sequence, and red giants) and in metal-deficient stars. Metal-deficient stars specify the conditions at the time of the formation of the Galaxy, while the young stars specify current conditions. The observations for this project have been or are being carried out in collabo- ration with Lambert (Uni. of Texas), Bond (Space Telescope Science Inst.), and Rich (Columbia).
