@article{4e8bfda1b3a144b985faf9b5f23432e8,
title = "Discovery of eight new extremely metal-poor galaxies in the sloan digital sky survey",
abstract = "We report the discovery of eight new extremely metal-poor galaxies [XMPGs; 12 + log (O/H) < 7.65] and the recovery of four previously known or suspected XMPGs (I Zw 18, HS 0822+3542, HS 0837+4717, and All 16+517) using Sloan Digital Sky Survey (SDSS) spectroscopy. These new objects were identified after an analysis of 250,000 galaxy spectra within an area of ∼3000 deg 2 on the sky. Our oxygen abundance determinations have an accuracy of ≤0.1 dex and are based on the temperature-sensitive [O III] λ4363 line and on the direct calculation of the electron temperature. We briefly discuss a new method of oxygen abundance determinations using the [O II] λλ 7319, 7330 lines that is particularly useful for SDSS emission-line spectra with redshifts ≤0.024 since the [O II ] λ 3727 emission line falls outside of the SDSS wavelength range. We detect XMPGs with redshifts ranging from 0.0005 to 0.0443 and Mg luminosities from -12.4 to -18.6 mag. Our eight new XMPGs increase the number of known metal-deficient galaxies by approximately one-quarter. The estimated surface density of XMPGs is 0.004 deg-2 for r ≤ 17.77 mag.",
keywords = "Galaxies: abundances, Galaxies: dwarf, Galaxies: evolution",
author = "Kniazev, {Alexei Y.} and Grebel, {Eva K.} and Lei Hao and Strauss, {Michael A.} and Jonathan Brinkmann and Masataka Fukugita",
note = "Funding Information: L. H. and M. A. S. acknowledge the support of NSF grant AST 00-71079. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the US Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS7 is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are the University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, the University of Pittsburgh, Princeton University, the US Naval Observatory, and the University of Washington. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.",
year = "2003",
month = aug,
day = "20",
doi = "10.1086/378259",
language = "English (US)",
volume = "593",
pages = "L73--L76",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 II",
}