Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Horizontal-Branch Morphology and the Photometric Evolution of Old
  Stellar Populations   Theoretical integrated broad-band colors ranging from far-UV to near-IR have
been computed for old stellar systems from our evolutionary population
synthesis code. These models take into account, for the first time, the
detailed systematic variation of horizontal-branch (HB) morphology with age and
metallicity. Our models show that some temperature-sensitive color indices are
significantly affected by the presence of `blue HB stars'. Our models are
calibrated in the B-V, V-I, C-T1, and M-T1 vs. [Fe/H] planes, using
low-reddened Galactic globular clusters (GCs) [E(B-V) < 0.2] and the relative
age difference between the older inner halo Galactic GCs and younger outer halo
counterparts is well reproduced. Several empirical linear color-metallicity
transformation relations are assessed with our models and it is noted that they
may not be safely used to estimate metallicity if there are sizable age
differences amongst GCs within and between galaxies. It is anticipated that the
detailed population models presented here coupled with further precise
spectrophotometric observations of globular cluster systems in external
galaxies from the large ground-based telescopes and space UV facilities will
enable us to accurately estimate their ages and metallicities. (abridged)

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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
2
The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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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: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: physics
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The categories of this paper are: econ