Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic fields and differential rotation on the pre-main sequence II:
  The early-G star HD 141943 - coronal magnetic field, H-alpha emission and
  differential rotation   Spectropolarimetric observations of the pre-main sequence early-G star HD
141943 were obtained at three observing epochs (2007, 2009 and 2010). The
observations were obtained using the 3.9-m Anglo-Australian telescope with the
UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor
instrument. The brightness and surface magnetic field topologies (given in
Paper I) were used to determine the star's surface differential rotation and
reconstruct the coronal magnetic field of the star.
  The coronal magnetic field at the 3 epochs shows on the largest scales that
the field structure is dominated by the dipole component with possible evidence
for the tilt of the dipole axis shifting between observations. We find very
high levels of differential rotation on HD 141943 (~8 times the solar value for
the magnetic features and ~5 times solar for the brightness features) similar
to that evidenced by another young early-G star, HD 171488. These results
indicate that a significant increase in the level of differential rotation
occurs for young stars around a spectral type of early-G. Also we find for the
2010 observations that there is a large difference in the differential rotation
measured from the brightness and magnetic features, similar to that seen on
early-K stars, but with the difference being much larger. We find only
tentative evidence for temporal evolution in the differential rotation of HD
141943.

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The categories of this paper are: comp-gas
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
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The categories of this paper are: q-bio
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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: chao-dyn