Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Is KR Cygni a Triple Star System?   New multi-color UBVR light curves of the eclipsing binary KR Cyg were
obtained in 2005. Photometric solutions were derived using the Wilson- Devinney
method. The result shows that KR Cyg is a near-contact binary system with a
large effective temperature difference between the components, approximately
5230 K. All the times of minimum light were collected and combined with our
observations obtained in 2010 and 2011. Analysing all the times of mid-eclipse,
we found for the first time a possible periodic oscillation with an amplitude
of 0.001 days and a period of ~76 years. The periodic oscillation could be
explained by the light-time effect due to a presumed third component.

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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
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The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
3
The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg