Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Short Period End of the Distribution of Contact Binary Stars   Contact binary systems (also known as W UMa systems) consist of a pair of
hydrogen-burning dwarf stars orbiting each other so closely that they share a
common envelope. Although they are relatively common, there is as yet no
established consensus on the principle evolutionary questions surrounding them:
how do they form, how do they evolve over time, what do they become?
  One observational clue to their evolutionary history has been the abrupt
termination of the orbital period distribution around 5.2 hours. We have
undertaken an observational study of this by 1) discovery of fast W UMa systems
in our Calvin-Rehoboth Observatory data archive, 2) follow-up with the
Calvin-Rehoboth Observatory of candidate fast systems from the Catalina Sky
Survey, and 3) follow-up of other reports of potentially fast systems in other
recently published surveys. We find the follow-up to have been particularly
important as many surveys taken for other purposes lead to ambiguous or
incorrect claims for periods less than five hours.
  Our results to date may be characterized as showing two distinct components:
the steeply decaying tail associated with the previously known cutoff along
with a low-amplitude, but apparently uniform distribution that extends down to
3.6 hours. The confirmation at greater sensitivity of the abruptness of the
cutoff seems to imply that the dominant mechanism for system formation (or the
mechanism that determines system lifetime) does have a strong period
dependence. At the same time, there appears to be a second mechanism at work as
well which leads to the formation of the ultrafast component of the histogram.

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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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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: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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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: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg