Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: M31 Globular Clusters: Colors and Metallicities   We present a new catalog of photometric and spectroscopic data on M31
globular clusters. The catalog includes new optical and near-infrared
photometry for a substantial fraction of the 435 clusters and cluster
candidates. We use these data to determine the reddening and intrinsic colors
of individual clusters, and find that the extinction laws in the Galaxy and M31
are not significantly different. There are significant (up to 0.2mag in V-K)
offsets between the clusters' intrinsic colors and simple stellar population
colors predicted by population synthesis models; we suggest that these are due
to systematic errors in the models. The distributions of M31 clusters'
metallicities and metallicity-sensitive colors are bimodal, with peaks at
[Fe/H] ~ -1.4 and -0.6. The distribution of V-I is often bimodal in elliptical
galaxies' globular cluster systems, but is not sensitive enough to metallicity
to show bimodality in M31 and Galactic cluster systems. The radial distribution
and kinematics of the two M31 metallicity groups imply that they are analogs of
the Galactic `halo' and `disk/bulge' cluster systems. The globular clusters in
M31 have a small radial metallicity gradient, suggesting that some dissipation
occurred during the GCS formation. The lack of correlation between cluster
luminosity and metallicity in M31 GCs shows that self-enrichment is not
important in GC formation.

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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio