Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Araucaria Project: The First-Overtone Classical Cepheid in the
  Eclipsing System OGLE-LMC-CEP-2532   We present here the first spectroscopic and photometric analysis of the
double-lined eclipsing binary containing the classical, first-overtone Cepheid
OGLE-LMC-CEP-2532 (MACHO 81.8997.87). The system has an orbital period of 800
days and the Cepheid is pulsating with a period of 2.035 days.
  Using spectroscopic data from three high-class telescopes and photometry from
three surveys spanning 7500 days we are able to derive the dynamical masses for
both stars with an accuracy better than 3%. This makes the Cepheid in this
system one of a few classical Cepheids with an accurate dynamical mass
determination (M_1=3.90 +/- 0.10 M_sun). The companion is probably slightly
less massive (3.82 +/- 0.10 M_sun), but may have the same mass within errors
(M_2/M_1= 0.981 +/- 0.015). The system has an age of about 185 million years
and the Cepheid is in a more advanced evolutionary stage.
  For the first time precise parameters are derived for both stars in this
system. Due to the lack of the secondary eclipse for many years not much was
known about the Cepheid's companion. In our analysis we used extra information
from the pulsations and the orbital solution from the radial velocity curve.
The best model predicts a grazing secondary eclipse shallower than 1 mmag,
hence undetectable in the data, about 370 days after the primary eclipse.
  The dynamical mass obtained here is the most accurate known for a
first-overtone Cepheid and will contribute to the solution of the Cepheid mass
discrepancy problem.

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The categories of this paper are: dg-ga
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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: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: funct-an