Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Physical Properties of the Red Supergiant WOH G64: The Largest Star
  Known?   WOH G64 is an unusual red supergiant (RSG) in the Large Magellanic Cloud
(LMC), with a number of properties that set it apart from the rest of the LMC
RSG population, including a thick circumstellar dust torus, an unusually late
spectral type, maser activity, and nebular emission lines. Its reported
physical properties are also extreme, including the largest radius for any star
known and an effective temperature that is much cooler than other RSGs in the
LMC, both of which are at variance with stellar evolutionary theory. We fit
moderate-resolution optical spectrophotometry of WOH G64 with the MARCS stellar
atmosphere models, determining an effective temperature of 3400 +/- 25 K. We
obtain a similar result from the star's broadband V - K colors. With this
effective temperature, and taking into account the flux contribution from the
aysmmetric circumstellar dust envelope, we calculate log(L/L_sun) = 5.45 +/-
0.05 for WOH G64, quite similar to the luminosity reported by Ohnaka and
collaborators based on their radiative transfer modeling of the star's dust
torus. We determine a radius of R/R_sun = 1540, bringing the size of WOH G64
and its position on the H-R diagram into agreement with the largest known
Galactic RSGs, although it is still extreme for the LMC. In addition, we use
the Ca II triplet absorption feature to determine a radial velocity of 294 +/-
2 km/s for the star; this is the same radial velocity as the rotating gas in
the LMC's disk, which confirms its membership in the LMC and precludes it from
being an unusual Galactic halo giant. Finally, we describe the star's unusual
nebula emission spectrum; the gas is nitrogen-rich and shock-heated, and
displays a radial velocity that is significantly more positive than the star
itself by 50 km/s.

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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: physics
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ph