Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectrophotometry and period analysis of the sdB eclipsing binary HW
  Virginis   New CCD observations of the pre-cataclysmic binary HW Virginis are presented
and discussed. The R-filtered CCD photometry was supplemented with medium-band
(Cousins VRI) spectrophotometry based on low-resolution objective-prism
spectra. The period variation is reanalysed by means of the standard O-C
technique. The new data support the conclusions of Kilkenny et al. (2000) on
the strong and continuous period change. The long-term period variation can be
described approximately with two linear branches in the O-C diagram
corresponding to a sudden period jump between two constant periods around JD
2448500 (1991). Additional smooth small-scale changes in the period distort the
linearity. The present data do not support the hypothetical light-time effect
of Cakirli & Devlen (1999). The eclipse depths in V, R, and I do not show
colour dependence, which suggests negligible continuum variations due to the
cool secondary component in the far-red region (up to 8800 AA). The magnitude
of the reflection effect was used to estimate the mean effective temperature of
the illuminated hemisphere of the secondary. The result is 13300\pm200 K or
11000\pm200 K, depending on the primary temperature (35000 K or 26000 K). An
albedo near unity is implied for the cool component.

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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: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci