Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Irregular changes in H{\alpha} emission line of V423 Aur observed by
  LAMOST Medium-Resolution Spectrographs   We obtained 7 spectra of the Be star V423 Aur on Dec. 5th, 2017 using the
LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds.
These spectra show the irregular H{\alpha} emission line profile variations
(LPVs). In the seven spectra, from the 4th to 7th, the left part of H{\alpha}
profile even show excess. However, no variation can be seen from the follow-up
observation of photometry by 1.26-m telescope and High-Resolution spectra by
2.16-m telescope. According to the High-Resolution spectra, we conclude that it
is a B7V type star with E(B-V)= 0.709{\pm}0.036 and its vsini is {\sim}
221.8km/s. The short-term H{\alpha} LPVs could be explained as a result of the
transient ejection of matter from rotating disk or shell around V423 Aur.

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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
1
The categories of this paper are: cs
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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: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: physics