|Annu. Rev. Astron. Astrophys. 1997. 35:
Copyright © 1997 by . All rights reserved
Reprinted with kind permission from , 4139 El Camino Way, Palo Alto, California, USA
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Abstract. The metallicity of stars in the Galaxy ranges from [Fe/H] = -4 to +0.5 dex, and the solar iron abundance is (Fe) = 7.51 ± 0.01 dex. The average values of [Fe/H] in the solar neighborhood, the halo, and Galactic bulge are -0.2, -1.6, and -0.2 dex respectively.
Detailed abundance analysis reveals that the Galactic disk, halo, and bulge exhibit unique abundance patterns of O, Mg, Si, Ca, and Ti and neutron-capture elements. These signatures show that environment plays an important role in chemical evolution and that supernovae come in many flavors with a range of element yields.
The 300-fold dispersion in heavy element abundances of the most metal-poor stars suggests incomplete mixing of ejecta from individual supernova, with vastly different yields, in clouds of ~ 106 M.
The composition of Orion association stars indicates that star-forming regions are significantly self-enriched on time scales of 80 million years. The rapid self-enrichment and inhomogeneous chemical evolution models are required to match observed abundance trends and the dispersion in the age-metallicity relation.
Key words: abundances, chemical composition, the Galaxy, nucleosynthesis, stars
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