Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Alpha Enhancement and the Metallicity Distribution Function of Plaut's
  Window   We present Fe, Si, and Ca abundances for 61 giants in Plaut's Window
(l=-1,b=-8.5) and Fe abundances for an additional 31 giants in a second, nearby
field (l=0,b=-8) derived from high resolution (R~25,000) spectra obtained with
the Blanco 4m telescope and Hydra multifiber spectrograph. The median
metallicity of red giant branch (RGB) stars in the Plaut field is ~0.4 dex
lower than those in Baade's Window, and confirms the presence of an iron
abundance gradient along the bulge minor axis. The full metallicity range of
our (biased) RGB sample spans -1.5<[Fe/H]<+0.3, which is similar to that found
in other bulge fields. We also derive a photometric metallicity distribution
function for RGB stars in the (l=-1,b=-8.5) field and find very good agreement
with the spectroscopic metallicity distribution. The radial velocity and
dispersion data for the bulge RGB stars are in agreement with previous results
of the BRAVA survey, and we find evidence for a decreasing velocity dispersion
with increasing [Fe/H]. The [alpha/Fe] enhancement in Plaut field stars is
nearly identical to that observed in Baade's window, and suggests that an
[alpha/Fe] gradient does not exist between b=-4 and -8. Additionally, a subset
of our sample (23 stars) appear to be foreground red clump stars that are very
metal--rich, exhibit small metallicity and radial velocity dispersions, and are
enhanced in alpha elements. While these stars likely belong to the Galactic
inner disk population, they exhibit [alpha/Fe] ratios that are enhanced above
the thin and thick disk.

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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph