Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Normal Branch Quasi-Periodic Oscillations in Sco X-1: Viscous
  Oscillations of a Spherical Shell Near the Neutron Star   We present a comprehensive classification of all observed QPOs within the
framework of the transition layer model using a large set of Rossi X-ray Timing
Explorer (RXTE) data for Sco X-1. The model assumes an optically thin material
along the observer's line of sight in the horizontal branch and an increasingly
optically thick material while in the other two branches that is consistent
with X-ray and radio observations and the disk transition layer model of QPOs.
We identify the ~ 6 Hz frequencies in the normal branch as acoustic
oscillations of a spherical shell around the neutron star (NS) that is formed
after radiation pressure near the Eddington accretion rate destroys the disk.
The size of the shell is on the order of one NS radii from the NS. We also
estimate the upper limit of Sco X-1's magnetic field to be 0.7 x 10^6 G at
about one NS radii above the NS surface while in the horizontal X-ray branch.

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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin