Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The 7.5 Magnitude Limit Sample of Bright Short-Period Binary Stars. I.
  How Many Contact Binaries Are There?   A sample of bright contact binary stars (W UMa-type or EW, and related: with
beta Lyr light curves, EB, and ellipsoidal, ELL - in effect, all but the
detached, EA), to the limit of Vmax = 7.5 magnitude is deemed to include all
discoverable short-period (P<1 days) binaries with photometric variation larger
than about 0.05 magnitude. Of the 32 systems in the final sample, 11 systems
have been discovered by the Hipparcos satellite. The combined spatial density
is evaluated at (1.02+/-0.24)x10^-5 pc^-3. The Relative Frequency of Occurrence
(RFO), defined in relation to the Main Sequence stars, depends on the
luminosity. An assumption of RFO~1/500 for MV>+1.5 is consistent with the data,
although the number statistics is poor with the resulting uncertainty in the
spatial density and the RFO by a factor of about two. The RFO rapidly decreases
for brighter binaries to a level of 1/5,000 for MV<+1.5 and to 1/30,000 for
MV<+0.5. The high RFO of 1/130, previously determined from the deep OGLE-I
sample of Disk Population W UMa-type systems towards Baade's Window, is
inconsistent with and unconfirmed by the new results. Possible reasons for the
large discrepancy are discussed. They include several observational effects,
but also a possibility of a genuine increase in the contact-binary density in
the central parts of the Galaxy.

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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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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: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th