Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Abundances of carbon-enhanced metal-poor stars as constraints on their
  formation   An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as
their iron abundance, [Fe/H], decreases below [Fe/H] = -2.0. The CEMP-s stars
have the highest absolute carbon abundances, [C/H], and are thought to owe
their enrichment in carbon and the slow neutron-capture (s-process) elements to
mass transfer from a former asymptotic giant-branch (AGB) binary companion. The
most Fe-poor CEMP stars are normally single, exhibit somewhat lower [C/H] than
CEMP-s stars, but show no s-process element enhancement (CEMP-no stars). CNO
abundance determinations offer clues to their formation sites. C, N, Sr, and Ba
abundances (or limits) and 12C/13C ratios where possible are derived for a
sample of 27 faint metal-poor stars for which the X-shooter spectra have
sufficient S/N ratios. These moderate resolution, low S/N (~10-40) spectra
prove sufficient to perform limited chemical tagging and enable assignment of
these stars into the CEMP sub-classes (CEMP-s and CEMP-no). According to the
derived abundances, 17 of our sample stars are CEMP-s and three are CEMP-no,
while the remaining seven are carbon-normal. For four CEMP stars, the
sub-classification remains uncertain, and two of them may be pulsating AGB
stars. The derived stellar abundances trace the formation processes and sites
of our sample stars. The [C/N] abundance ratio is useful to identify stars with
chemical compositions unaffected by internal mixing, and the [Sr/Ba] abundance
ratio allows us to distinguish between CEMP-s stars with AGB progenitors and
the CEMP-no stars. Suggested formation sites for the latter include faint
supernovae with mixing and fallback and/or primordial, rapidly-rotating,
massive stars (spinstars). X-shooter spectra have thus proved to be valuable
tools in the continued search for their origin. Abridged.

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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin