Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The quest for companions to post-common envelope binaries: I. Searching
  a sample of stars from the CSS and SDSS   As part of an ongoing collaboration between student groups at high schools
and professional astronomers, we have searched for the presence of
circum-binary planets in a bona-fide unbiased sample of twelve post-common
envelope binaries (PCEBs) from the Catalina Sky Survey (CSS) and the Sloan
Digital Sky Survey (SDSS). Although the present ephemerides are significantly
more accurate than previous ones, we find no clear evidence for orbital period
variations between 2005 and 2011 or during the 2011 observing season. The
sparse long-term coverage still permits O-C variations with a period of years
and an amplitude of tens of seconds, as found in other systems. Our
observations provide the basis for future inferences about the frequency with
which planet-sized or brown-dwarf companions have either formed in these
evolved systems or survived the common envelope (CE) phase.

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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
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The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
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The categories of this paper are: econ