Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Europium s-process signature at close-to-solar metallicity in stardust
  SiC grains from AGB stars   Individual mainstream stardust silicon carbide (SiC) grains and a
SiC-enriched bulk sample from the Murchison carbonaceous meteorite have been
analyzed by the Sensitive High Resolution Ion Microprobe - Reverse Geometry
(SHRIMP-RG) for Eu isotopes. The mainstream grains are believed to have
condensed in the outflows of 1.5 to 3 Msun carbon-rich asymptotic giant branch
(AGB) stars with close-to-solar metallicity. The 151Eu fractions [fr(151Eu) =
151Eu/(151Eu+153Eu)] derived from our measurements are compared with previous
astronomical observations of carbon-enhanced metal-poor (CEMP) stars enriched
in elements made by slow neutron captures (the s-process). Despite the
difference in metallicity between the parent stars of the grains and the
metal-poor stars, the fr(151Eu) values derived from our measurements agree well
with fr(151Eu) values derived from astronomical observations. We have also
compared the SiC data with theoretical predictions of the evolution of Eu
isotopic ratios in the envelope of AGB stars. Because of the low Eu abundances
in the SiC grains, the fr(151Eu) values derived from our measurements show
large uncertainties, being in most cases larger than the difference between
solar and predicted fr(151Eu) values. The SiC aggregate yields a fr(151Eu)
value within the range observed in the single grains and provides a more
precise result (fr(151Eu) = 0.54 +/- 0.03, 95 percent conf.), but is
approximately 12 percent higher than current s-process predictions. The AGB
models can match the SiC data if we use an improved formalism to evaluate the
contribution of excited nuclear states in the calculation of the 151Sm(n,g)
stellar reaction rate.

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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat