Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Periodic Optical Outbursts from the Be/Neutron Star Binary AX
  J0049.4-7323   The optical light curve of the Be/neutron star binary AX J0049.4-7323 has
been investigated using data from the MACHO and OGLE-II projects. This X-ray
source, whose neutron star has a very slow rotation rate (P_pulse=755.5 sec),
shows optical outbursts every 394 days. The regularity of these outbursts
suggests that their recurrence time is the orbital period of the system. During
the outbursts the system brightens and becomes slightly redder. A possible
interpretation is that a portion of the equatorial disk is excited as the
neutron star passes through it during periastron passage. In the intervals
between outbursts the light curve shows 11-day quasi-periodic varability which
may be associated with the rotation of the Be star's extended disk.

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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn