I ZW 18 and the existence of very metal poor blue compact dwarf galaxies

Abstract

view Abstract Citations (205) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS I ZW 18 and the Existence of Very Metal Poor Blue Compact Dwarf Galaxies Kunth, D. ; Sargent, W. L. W. Abstract Existing searches for metal-poor galaxies are reviewed, and it is argued that the failure to find galaxies more oxygen-poor than 1 Zw 18 is a result not of observational selection but rather of the fact that H II regions are used to derive the compositions of distant gas-rich systems. It is pointed out that, provided the bursts of star formation in the blue compact galaxies last much longer than the evolutionary time scale of a typical massive star, a minimum metal abundance close to that observed in I Zw 18 must be found in any H II region. This is due to the fact that the same massive stars produce both heavy elements and ionizing photons, while on short time scales mixing of newly formed heavy elements is confined to the H II region. Accordingly, emission line spectra cannot, in principle, give the true heavy element abundance in primordial systems. Publication: The Astrophysical Journal Pub Date: January 1986 DOI: 10.1086/163828 Bibcode: 1986ApJ...300..496K Keywords: Compact Galaxies; Cosmochemistry; Dwarf Galaxies; Galactic Evolution; Metallicity; Abundance; Blue Stars; H Ii Regions; Hydrogen; Oxygen; Quasars; Stellar Evolution; Astrophysics; GALAXIES: EVOLUTION; GALAXIES: INDIVIDUAL ALPHANUMERIC: I ZW 18; GALAXIES: STELLAR CONTENT; STARS: FORMATION full text sources ADS | data products SIMBAD (2) NED (2)