Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hanle Effect as a Diagnostic of Magnetic Fields in Stellar
  Envelopes. V. Thin Lines from Keplerian Disks   This paper focuses on the polarized profiles of resonance scattering lines
that form in magnetized disks. Optically thin lines from Keplerian planar disks
are considered. Model line profiles are calculated for simple field topologies
of axial fields (i.e., vertical to the disk plane) and toroidal fields (i.e.,
purely azimuthal). A scheme for discerning field strengths and geometries in
disks is developed based on Stokes Q-U diagrams for the run of polarization
across line profiles that are Doppler broadened by the disk rotation. A
discussion of the Hanle effect for magnetized disks in which the
magnetorotational instability (MRI) is operating is also presented. Given that
the MRI has a tendency to mix the vector field orientation, it may be difficult
to detect the disk fields with the longitudinal Zeeman effect, since the
amplitude of the circularly polarized signal scales with the net magnetic flux
in the direction of the observer. The Hanle effect does not suffer from this
impediment, and so a multi-line analysis could be used to constrain field
strengths in disks dominated by the MRI.

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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc