Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stable and Unstable Regimes of Mass Accretion onto RW Aur A   We present monitoring observations of the active T Tauri star RW Aur, from
2010 October to 2015 January, using optical high-resolution (R>10000)
spectroscopy with CFHT-ESPaDOnS. Optical photometry in the literature shows
bright, stable fluxes over most of this period, with lower fluxes (by 2-3 mag.)
in 2010 and 2014. In the bright period our spectra show clear photospheric
absorption, complicated variation in the Ca II 8542 A emission}profile shapes,
and a large variation in redshifted absorption in the O I 7772 and 8446 A and
He I 5876 A lines, suggesting unstable mass accretion during this period. In
contrast, these line profiles are relatively uniform during the faint periods,
suggesting stable mass accretion. During the faint periods the photospheric
absorption lines are absent or marginal, and the averaged Li I profile shows
redshifted absorption due to an inflow. We discuss (1) occultation by
circumstellar material or a companion and (2) changes in the activity of mass
accretion to explain the above results, together with near-infrared and X-ray
observations from 2011-2015. Neither scenario can simply explain all the
observed trends, and more theoretical work is needed to further investigate
their feasibilities.

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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph