Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SDSSJ212531.92-010745.9 - the first definite PG1159 close binary system   The archival spectrum of SDSSJ212531.92-010745.9 shows not only the typical
signature of a PG1159 star, but also indicates the presence of a companion. Our
aim was the proof of the binary nature ofthis object and the determination of
its orbital period.We performed time-series photometry of
SDSSJ212531.92-010745.9. We observed the object during 10 nights, spread over
one month, with the Tuebingen 80cm and the Goettingen 50cm telescopes. We
fitted the observed light curve with a sine and simulated the light curve of
this system with the nightfall program. Furthermore, we compared the spectrum
of SDSSJ212531.92-010745.9 with NLTE models, the results of which also
constrain the light curve solution. An orbital period of 6.95616(33)h with an
amplitude of 0.354(3)mag is derived from our observations. A pulsation period
could not be detected. For the PG1159 star we found, as preliminary results
from comparison with our NLTE models, Teff about 90000K, log g about 7.60, and
the abundance ratio C/He = 0.05 by number fraction. For the companion we
obtained with a mean radius of 0.4 +/- 0.1 Rsol, a mass of 0.4 +/- 0.1 Msol,
and a temperature of 8200K on the irradiated side, good agreement between the
observed light curve and the nightfall simulation, but we do not regard those
values as final.

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The categories of this paper are: bayes-an
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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: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th