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Ultraviolet to near-infrared spectral distributions of star-forming galaxies: Metallicity and age effectsSpectral distributions from the UV to the near-IR of a sample of 44 star-forming galaxies are used to calculate the metallicity (O/H), star-formation rate (SFR) and age of the starbursts. The oxygen abundance covers the range 8.3 less than O/H less than 9.4 and nitrogen (N) is found to be mostly a product of secondary nucleosynthesis for O/H greater than 8.4. Due to its secondary origin, N/O ratios up to approximately equals 4 times the solar value can be obtained for metal-rich starbursts. The SFR ranges 0.01 to 100 solar mass/year. The lower metallicity galaxies seem to be experiencing an instantaneous burst of star formation, with ages ranging from under 5 x 10(exp 6) to 10(exp 7) yr. The highest metallicity galaxies are most probably experiencing a continuous burst. Correlations between the calculated quantities and several spectral features are investigated. We found a highly significant correlation between the equivalent width W(C IV lambda 1550)-a stellar (absorption) feature- and the oxygen abundance of the emitting gas (O/H). Thus we show for the first time that the stellar metallicity is well correlated with the gas metallicity in star-bursting galaxies. The equivalent width W(Si IV lambda 1400) and the emission line ratio (N II) lambda lambda 6548.84/H(sub alpha) also correlate well with O/H, and all three features can be used as metallicity indicators for star-forming galaxies. The continuum color between lambda 1400 and lambda 3500 (C(14 - 35)) is shown to correlate with O/H, although it is better correlated with E(B - V). It was not possible to disentangle the metallicity from the reddening effect in C(14- 35). We estimate that the reddening affecting the UV continuum is about half the one derived from the Balmer decrement of the emitting gas. The SFR correlates well with the galaxy luminosity and there is no dependence of the continuum color on the SFR. The higher metallicities are only found in the more luminous galaxies, while low metallicities are found over the whole luminosity interval (-16 less than M(sub B) less than -23, H(sub 0) = 50 km/sec/Mpc) covered by the sample.
Document ID
19950030048
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Storchi-Bergmann, Thaisa
(IF-UFRGS Porto Alegre, Brazil)
Calzetti, Daniela
(Space Telescope Science Institute, Baltimore, MD United States)
Kinney, Anne L.
(Space Telescope Science Institute, Baltimore, MD United States)
Date Acquired
August 16, 2013
Publication Date
July 10, 1994
Publication Information
Publication: The Astrophysical Journal
Volume: 429
Issue: 2 pt
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A61647
Funding Number(s)
CONTRACT_GRANT: NAG5-1143
Distribution Limits
Public
Copyright
Other

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