On the Evolution of Helium Nitrogen and Oxygen Abundances in Dwarf Irregular Gal ADS
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Within the framework of the closed box model of chemical evolution of galaxies the evolution
of nitrogen and oxygen abundances in dwarf irregular galaxies is considered. We show that …

Oxygen abundances are obtained by optical spectrophotometry of H II regions in seven
nearby dwarf irregular galaxies. All of these yield oxygen abundances of less than 1/10 of …

We present H α imaging and optical spectrophotometry of H II regions in the low surface
brightness dwarf irregular galaxy DDO 154. The galaxy possesses a very small population …

Deep groundbased spectra of Hubble V and Hubble X, the two largest and brightest H ii
regions in the Local Group dwarf galaxy, NGC 6822, are presented. The extinction …

We present optical spectrophotometry of an H II region in the Local Group dwarf irregular
galaxy GR 8. The derived oxygen abundance is 0.03 of solar, which is, within errors, equal …

Numerical models of chemical evolution have been computed for a sample of 40 dwarf
irregular galaxies by assuming bursts of star formation and taking galactic winds into …

The neutral atomic hydrogen (HI) in nine dwarf irregular galaxies, with absolute magnitude
fainter than M_B_=-14^ m^: LGS-3, UGC 4483, DDO 69 (Leo A), C Vn dwA, DDO 155 (GR …

We discuss the chemical evolution of dwarf irregular and blue compact galaxies in light of
recent data, new stellar yields, and chemical evolution models. We examine the abundance …

This paper is the first in a series presenting a sample of 30 late-type dwarf galaxies,
observed with the Westerbork Synthesis Radio Telescope (WSRT) in the 21-cm line of …