Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determination of the physical characteristics of the variable stars in
  the direction of the open cluster NGC 6811 through $uvby\beta$ photoelectric
  photometry   The study of open clusters and their short period variable stars is
fundamental in stellar evolution. Because the cluster members are formed in
almost the same physical conditions, they share similar stellar properties such
age and chemical composition. The assumption of common age, metallicity and
distance impose strong constraints when modeling an ensemble of short period
pulsators belonging to open clusters (e.g. Fox Machado et al., 2006). Very
recently, Luo et al. (2009) carried out a search for variable stars in the
direction of NGC 6811 with CCD photometry in B and V bands. They detected a
total of sixteen variable stars. Among these variables, twelve were catalogued
as $\delta$ {\it Scuti} stars, while no variability type was assigned to the
remaining stars. In this paper we present $uvby\beta$ photoelectric photometry
for the variable stars in the direction of NGC 6811.

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The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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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: comp-gas
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The categories of this paper are: cond-mat
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph