The comparative chemical evolution of an isolated dwarf galaxy: A vlt and keck spectroscopic survey of wlm

Ryan Leaman, Kim A. Venn, Alyson M. Brooks, Giuseppina Battaglia, Andrew A. Cole, Rodrigo A. Ibata, Mike J. Irwin, Alan W. McConnachie, J. Trevor Mendel, Else Starkenburg, Eline Tolstoy

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Building on our previous spectroscopic and photometric analysis of the isolated Local Group dwarf irregular (dIrr) galaxy WLM, we present a comparison of the metallicities of its red giant branch stars with respect to the well-studied Local Group dwarf spheroidal galaxies (dSphs) and Magellanic Clouds. We calculate a mean metallicity of [Fe/H] =-1.28 ± 0.02 and an intrinsic spread in metallicity of σ = 0.38 ± 0.04 dex, similar to the mean and spread observed in the massive dSph Fornax and the Small Magellanic Cloud. Thus, despite WLM's isolated environment, its global metallicity still follows expectations for mass and its global chemical evolution is similar to other nearby luminous dwarf galaxies (gas-rich or gas-poor). The data also show a radial gradient in [Fe/H] of d[Fe/H]/drc = -0.04 ± 0.04 dex , which is flatter than that seen in the unbiased and spatially extended surveys of dSphs. Comparison of the spatial distribution of [Fe/H] in WLM, the Magellanic Clouds, and a sample of Local Group dSphs shows an apparent dichotomy in the sense that the dIrrs have statistically flatter radial [Fe/H] gradients than the low angular momentum dSphs. The correlation between angular momentum and radial metallicity gradient is further supported when considering the Local Group dEs. This chemodynamic relationship offers a new and useful constraint for environment-driven dwarf galaxy evolution models in the Local Group.

Original languageEnglish (US)
Article number131
JournalAstrophysical Journal
Volume767
Issue number2
DOIs
StatePublished - Apr 20 2013

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • galaxies: abundances
  • galaxies: dwarf
  • galaxies: evolution
  • galaxies: individual (WLM) Local Group

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