Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Physical Characteristics of Binary Central Stars of Planetary
  Nebulae   A number of efforts are underway to detect close binary stars in planetary
nebulae. The primary goal of these studies is to determine the binary fraction
of central stars. The next stage is a detailed analysis of the binaries to
determine physical parameters for the systems. These analyses can be combined
with population synthesis models, common envelope evolution models, and
observed properties of nebulae to further understand the impact of binarity on
PN formation. I discuss the sample of known close binary central stars in
relation to other close binaries with a white dwarf, cataclysmic variables,
supernova Ia progenitors, and double degenerate systems.

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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
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The categories of this paper are: cs