Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The pecular magnetic field morphology of the white dwarf WD 1953-011:
  evidence for a large-scale magnetic flux tube?   We present and interpret new spectropolarimetric observations of the magnetic
white dwarf WD 1953-011. Circular polarization and intensity spectra of the
H$\alpha$ spectral line demonstrate the presence of two-component magnetic
field in the photosphere of this star. The geometry consists of a weak, large
scale component, and a strong, localized component. Analyzing the rotationally
modulated low-field component, we establish a rotation period $P_{rot} = 1.4480
\pm 0.0001$ days. Modeling the measured magnetic observables, we find that the
low-field component can be described by the superposition of a dipole and
quadrupole. According to the best-fit model, the inclination of the stellar
rotation axis with respect to the line of sight is $i \approx 20^\circ$, and
the angle between the rotation axis and the dipolar axis is $\beta \approx
10^\circ$. The dipole strength at the pole is about 180 kG, and the quadrupolar
strength is about 230 kG. These data suggest a fossil origin of the low-field
component. In contrast, the strong-field component exhibits a peculiar,
localized structure (``magnetic spot'') that confirms the conclusions of Maxted
and co-workers. The mean field modulus of the spot ($|B_{spot}| = 520 \pm 7$
kG) together with its variable longitudinal magnetic field having a maximum of
about +400 kG make it difficult to describe it naturally as a high-order
component of the star's global poloidal field. Instead, we suggest that the
observed strong-field region has a geometry similar to a magnetic flux tube.

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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
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The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
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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: gr-qc