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Article Contents
- ABSTRACT
- 1.INTRODUCTION
- 1.1.H II Regions in the Context of the ISM
- 1.2.Environments and Systematics
- 1.3.Internal Structure
- 1.4.Ionizing Clusters
- 2.METHODS OF ABUNDANCE DETERMINATION
- 2.1.The "Conventional" (Direct)
Method
- 2.2.Nebular Models
- 2.3."Bright-Line" Methods
- 3.ABUNDANCE GRADIENTS IN GALACTIC DISKS
- 3.1.The Phenomenon
- 3.2. Trends with Galaxy Type
- 3.3.Elements other than Oxygen
- 3.4.Comparison with the Galactic Abundance Gradient
- 3.5.Comparison with Chemical Evolution Models
- 4.ABUNDANCES IN METAL-POOR DWARF
GALAXIES
- 4.1.Nomenclature
- 4.2.The "I Zw 18 Problem" and the Mass-Metallicity
Relation
- 4.3.Dwarf Galaxies as Tests of the Simple Model
- 4.4.Dwarf Galaxies and the Extragalactic H II Region
Sequence
- 4.5.Elements other than Oxygen
- 5.HELIUM ABUNDANCES AND THE PRIMORDIAL COMPONENT
- 5.1.Cosmological Motivation
- 5.2.Demands on the Observations
- 5.3.Current Status and Future Prospects
- 6.SOME OUTSTANDING ISSUES
- 7.FUTURE PROSPECTS
- REFERENCES