The Early History of Our Galaxy: Chemical Evolution (invited Paper)
Abstract
A general review is given of chemical abundance determinations; particular emphasis is given to abundances of galactic and extragalactic metal-poor objects, since presumably they represent the abundances of the primeval material from which our Galaxy was formed. The following results are stressed: (1) most of the helium present in the galaxies of the local group as well as in other galaxies was produced before these objects were formed; (2) the heavy elements were produced mainly as the result of stellar evolution; (3) there is a chemical abundance gradient in our Galaxy and, by analogy with other galaxies, it is expected to be steeper near the nucleus; (4) the carbon and oxygen content of our Galaxy increased at a rate different from the metals, reaching their present abundance earlier than the other heavy elements; and (5) the increase of the iron abundance in the disk of our Galaxy with time has been small, while that of carbon is negligible; furthermore, as a group the super-metal-rich stars correspond to the old disk population. Several models of galactic chemical evolution are reviewed.
- Publication:
-
The Formation and Dynamics of Galaxies
- Pub Date:
- 1974
- Bibcode:
- 1974IAUS...58..141P
- Keywords:
-
- Abundance;
- Astronomical Models;
- Galactic Evolution;
- Interstellar Matter;
- Milky Way Galaxy;
- Chemical Composition;
- Galactic Structure;
- Heavy Elements;
- Helium;
- Intergalactic Media;
- Stellar Evolution;
- Astrophysics