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Paper: Low Metallicity Galaxies at Low Redshifts
Volume: 353, Stellar Evolution at Low Metallicity: Mass Loss, Explosions, Cosmology
Page: 349
Authors: Izotov, Y.I.
Abstract: The first generations of zero-metallicity stars are expected to be massive and hot producing copious amounts of hard ionizing radiation. Such stars are likely not present in the local universe. However there is the possibility to study stellar populations with metallicities intermediate between that in our Galaxy and zero metallicity. The best place to study the properties of lowmetallicity massive stars in the local universe is in metal-deficient emission-line dwarf galaxies. These stars with the heavy element mass fractions 1/3 - 1/50 that of the Sun can be considered as an intermediate case between the present-day high-metallicity stars and zero-metallicity first generation stars. The following topics are outlined in this review: 1) general characteristics and evolutionary status of the dwarf emission-line galaxies; 2) the primordial helium abundance and initial chemical composition of zero-metallicity stars; 3) heavy-element abundances of the ionized and neutral gas in dwarf emission-line galaxies; 4) observational evidence for stellar winds and Wolf-Rayet stars at low metallicities; 5) high-ionization nebular emission lines and the hardness of the ionizing radiation in low-metallicity dwarf galaxies.
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