Bibcode
Tolstoy, Eline; Starkenburg, Else; Mendel, J. Trevor; McConnachie, Alan W.; Irwin, Mike J.; Ibata, Rodrigo A.; Cole, Andrew A.; Battaglia, Giuseppina; Brooks, Alyson M.; Venn, Kim A.; Leaman, R.
Bibliographical reference
The Astrophysical Journal, Volume 767, Issue 2, article id. 131, 16 id. (2013).
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4
2013
Journal
Citations
82
Refereed citations
73
Description
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 {r_{c}^{-1}}, 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.
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