Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New activity in the large circumstellar disk of the Be-shell star 48 Lib   Spectroscopic, polarimetric, and high spectral resolution interferometric
data covering the period 1995-2011 are analyzed to document the transition into
a new phase of circumstellar disk activity in the classical Be-shell star 48
Lib. The long-term disk evolution is described using the V/R ratio of the
violet and red emission components of H alpha and Br gamma, radial velocities
and profiles of He I and optical metal shell lines, multi-band BVRI
polarimetry, broad-band and high-resolution interferometric visibilities and
phases. Spectroscopic signatures of disk asymmetries in 48 Lib vanished in the
late nineties but recovered some time between 2004 and 2007. Variations in the
radial velocity and line profile of conventional shell lines correlate with the
V/R behavior. They are shared by narrow absorption cores superimposed on
otherwise seemingly photospheric He I lines, which may form in high-density gas
at the inner disk close to the photosphere. Large radial velocity variations
continued also during the V/R-quiet years. The broad H-band interferometry
gives a disk diameter of (1.72+-0.2) mas (equivalent to 15 stellar radii),
position angle of the disk (50+-9) deg and a relatively low disk flattening of
1.66+-0.3. Within the errors the same disk position angle is derived from
polarimetric observations and from photocenter shifts across Br gamma. The
high-resolution interferometric visibility and phase profiles show a double or
even multiple-component structure. A preliminary estimate based on the size of
the Br gamma emitting region indicates a large diameter for the disk (tens of
stellar radii).

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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: math
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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: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
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The categories of this paper are: stat