Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Chemical Abundance Study of three RHB and two RGB stars in NGC6637
  (M69)   We present a detailed chemical abundance study of three red horizontal branch
and two red giant branch stars in the metal-rich globular cluster NGC 6637
(M69). The value of [Fe/H] derived from LTE calculations is $-$0.77 $\pm$ 0.02
dex. We also discuss the anticorrelation between oxygen and sodium abundances
in the program stars and compare the [Si/Ti] ratio of NGC 6637 with those of
other globular clusters.

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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio