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Title: Chemical cartography with apogee: Large-scale mean metallicity maps of the Milky Way disk

We present Galactic mean metallicity maps derived from the first year of the SDSS-III APOGEE experiment. Mean abundances in different zones of projected Galactocentric radius (0 < R < 15 kpc) at a range of heights above the plane (0 < |z| < 3 kpc), are derived from a sample of nearly 20,000 giant stars with unprecedented coverage, including stars in the Galactic mid-plane at large distances. We also split the sample into subsamples of stars with low- and high-[α/M] abundance ratios. We assess possible biases in deriving the mean abundances, and find that they are likely to be small except in the inner regions of the Galaxy. A negative radial metallicity gradient exists over much of the Galaxy; however, the gradient appears to flatten for R < 6 kpc, in particular near the Galactic mid-plane and for low-[α/M] stars. At R > 6 kpc, the gradient flattens as one moves off the plane, and is flatter at all heights for high-[α/M] stars than for low-[α/M] stars. Alternatively, these gradients can be described as vertical gradients that flatten at larger Galactocentric radius; these vertical gradients are similar for both low- and high-[α/M] populations. Stars with higher [α/M] appear to havemore » a flatter radial gradient than stars with lower [α/M]. This could suggest that the metallicity gradient has grown steeper with time or, alternatively, that gradients are washed out over time by migration of stars.« less
; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;  [15] ;
  1. New Mexico State University, Las Cruces, NM 88003 (United States)
  2. Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
  3. Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
  4. Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)
  5. Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)
  6. Department of Physics and Astronomy and JINA, Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI 48824 (United States)
  7. Observatório Nacional, São Cristóvão, Rio de Janeiro (Brazil)
  8. Texas Christian University, Fort Worth, TX 76129 (United States)
  9. Osservatorio Astronomico di Padova-INAF, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy)
  10. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
  11. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
  12. Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 ILD (United Kingdom)
  13. Research School of Astronomy and Astrophysics, Australian National University, Mt. Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia)
  14. Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400 (Brazil)
  15. Observatoire de la Cote d'Azur, Boulevard de l'Observatoire, B.P. 4229, F-06304 NICE Cedex 4 (France)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 147; Journal Issue: 5; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States