Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The stellar populations of the Fornax dwarf spheroidal galaxy   (abridged) We present B,V,I CCD photometry of about 40000 stars in four
regions of the Fornax dSph. Using the resultant CMDs, many already known
age-tracers are investigated, and new CMD features are also detected: we show
that blue HB stars may be present in the outer regions, and measure the
luminosity of the AGB bump. We measure a corrected distance modulus (m-M)o =
20.70+/-0.12, based on the RGB tip luminosity, which is in good agreement with
that obtained from the mean magnitude of old HB stars [(m-M)o=20.76+/-0.04] and
with previous results. The (B-I) distribution of the RG stars can be
approximately described as the superposition of two populations. The dominant
component, comprising ~70% of the red giant stars, consists of relatively
metal-enriched intermediate-age stars, whose mean metallicity is
[Fe/H]=-1.39+/-0.15 (the age-corrected metallicity would be [Fe/H] ~
-1.0+/-0.15). The dominant intermediate-age component has an intrinsic color
dispersion \sigma(B-I)=0.06+/-0.01mag, corresponding to a relatively low
abundance dispersion, \sigma[Fe/H]=0.12+/-0.02dex. In addition, there is a
small population of giants on the blue side of the RGB, whose spatial
distribution is consistent with that of old horizontal branch stars, and
completely different from that of the younger population. This unambiguously
qualifies them as old and metal-poor. The exceptional color width of the Fornax
RGB is therefore due to the presence of two main populations, yielding a large
abundance range (-2.0<[Fe/H]<-0.7). This evidence suggests a scenario in which
this galaxy started forming a stellar halo and its surrounding clusters
together about 10-13 Gyr ago, then a major SF episode occurred after several
Gyr.

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The categories of this paper are: quant-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an