Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor
  stars   From high-resolution VLT/UVES spectra (R~43,000), we determine abundances or
upper limits for Li, C, N, O, and other important elements, as well as 12C/13C
isotopic ratio for three Carbon enhanced metal poor stars. All three stars have
-3.30 <= [Fe/H] <= -2.85 and moderate to high CNO abundances. CS 22958-042 is
one of the most carbon-rich CEMP stars known ([C/Fe] = +3.2), while CS
29528-041 (one of the few N-enhanced metal-poor stars known) is one of the most
nitrogen rich ([N/Fe] = +3.0). Oxygen is very high in CS 31080-095 ([O/Fe] =
+2.35) and in CS 22958-042 ([O/Fe] = +1.35). All three stars exhibit [Sr/Fe] <
0; Ba is not detected in CS 22958-042 ([Ba/Fe] < -0.53), but it is moderately
enhanced ([Ba/Fe] ~ 1) in the other two stars. CS 22958-042 displays one of the
largest sodium overabundances yet found in CEMP stars ([Na/Fe] = +2.8). CS
22958-042 has 12C/13C = 9, similar to most other CEMP stars without enhanced
neutron-capture elements, while 12C/13C <= 40 in CS 31080-095. CS 31080-095 and
CS 29528-041 have A(Li) ~ 1.7, below the Spite Plateau, while Li is not
detected in CS 22958-042. CS 22958-042 is a CEMP-no star, but the other two
stars are in no known class of CEMP star and thus either constitute a new class
or are a link between the CEMP-no and CEMP-s classes, adding complexity to the
abundance patterns for CEMP stars. We interpret the abundance patterns in our
stars to imply that current models for the presumed AGB binary progenitors lack
an extra-mixing process, similar to those apparently operating in RGB stars.

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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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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: chem-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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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: dg-ga
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The categories of this paper are: physics
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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: hep-th
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The categories of this paper are: nucl-ex