![]() | Annu. Rev. Astron. Astrophys. 1997. 35:
503-556 Copyright © 1997 by Annual Reviews. All rights reserved |
Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA
For a PDF version of the article, click here.
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
Table of Contents