Empirical oxygen abundances and physical conditions for relatively low abundance H II regions

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168179· OSTI ID:6966719

Skillman, E D ^[1]

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1. Texas Univ., Austin (USA)

The utility of the emission-line ratio (3727 + 4959 + 5007 A)/H-beta as an estimate of the total oxygen abundance in H II regions of low abundance (less than 10 percent of the solar value) is discussed. Using both observational data where the 4363A line is measured and model H II regions it is concluded that, for low abundance systems, total oxygen abundances can be determined with an accuracy of + or - 0.2 dex in the absence of a 4363A measurement. An attempt is made to study the average behavior of the stellar effective temperature (Teff) and ionization parameter (U) with changing abundance in low abundance systems. It is shown that some diagnostic methods which are viable for high abundance systems are not capable of uniquely determining Teff and U in low abundance systems. The most promising method of determining Teff and U requires measuring emission lines of forbidden O II, O III, S II, and S III. 53 refs.

• OSTI ID: 6966719
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 347; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CHEMICAL COMPOSITION
CHEMISTRY
COSMIC GASES
COSMIC RADIO SOURCES
COSMOCHEMISTRY
ELEMENT ABUNDANCE
ELEMENTS
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
FLUIDS
FORBIDDEN TRANSITIONS
GASES
H2 REGIONS
INTERSTELLAR SPACE
IONIZATION
NONMETALS
OXYGEN
SPACE
SPECTRA
SULFUR