Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The 155-day X-ray cycle of the very massive Wolf-Rayet star Melnick 34
  in the Large Magellanic Cloud   The Wolf-Rayet star Mk 34 was observed more than 50 times as part of the deep
T-ReX Chandra ACIS-I X-ray imaging survey of the Tarantula Nebula in the Large
Magellanic Cloud conducted between 2014 May and 2016 January. Its brightness
showed one bright maximum and repeated faint minima which help define an X-ray
recurrence time of $155.1\pm0.1$ days that is probably the orbital period of an
eccentric binary system. The maximum immediately precedes the minimum in the
folded X-ray light curve as confirmed by new Swift XRT observations.
Notwithstanding its extreme median luminosity of
$1.2\times10^{35}\mathrm{erg}~\mathrm{s}^{-1}$, which makes it over an order of
magnitude brighter than comparable stars in the Milky Way, Mk 34 is almost
certainly a colliding-wind binary system. Its spectrum shows phase-related
changes of luminosity and absorption that are probably related to the orbital
dynamics of two of the most massive stars known.

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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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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: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: acc-phys