Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigating the origin and spectroscopic variability of the
  near-infrared HI lines in the Herbig star VV Ser   The origin of the near-infrared (NIR) HI emission lines in young stellar
objects are not yet understood. To probe it, we present multi-epoch LBT-LUCIFER
spectroscopic observations of the Pa{\delta}, Pa{\beta}, and Br{\gamma} lines
observed in the Herbig star VVSer, along with VLTI-AMBER Br{\gamma}
spectro-interferometric observations at medium resolution. Our spectroscopic
observations show line profile variability in all the HI lines. The strongest
variability is observed in the redshifted part of the line profiles. The
Br{\gamma} spectro-interferometric observations indicate that the Br{\gamma}
line emitting region is smaller than the continuum emitting region. To
interpret our results, we employed radiative transfer models with three
different flow configurations: magnetospheric accretion, a
magneto-centrifugally driven disc wind, and a schematic bipolar outflow. Our
models suggest that the HI line emission in VVSer is dominated by the
contribution of an extended wind, perhaps a bipolar outflow. Although the exact
physical process for producing such outflow is not known, this model is capable
of reproducing the averaged single-peaked line profiles of the HI lines.
Additionally, the observed visibilities, differential and closure phases are
best reproduced when a wind is considered. Nevertheless, the complex line
profiles and variability could be explained by changes in the relative
contribution of the magnetosphere and/or winds to the line emission. This might
indicate that the NIR HI lines are formed in a complex inner disc region where
inflow and outflow components might coexist. Furthermore, the contribution of
each of these mechanisms to the line appears time variable, suggesting a
non-steady accretion/ejection flow.

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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: supr-con
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The categories of this paper are: quant-ph