Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic field and prominences of the young, solar-like, ultra-rapid
  rotator V530 Per   We investigate signatures of magnetic fields and activity at the surface and
in the prominence system of the ultra-rapid rotator V530 Per, a G-type
solar-like member of the young open cluster $\alpha$~Persei. This object has a
rotation period shorter than all stars with available magnetic maps. With a
time-series of spectropolarimetric observations gathered with ESPaDOnS over 2
nights on the CFHT, we reconstruct the surface brightness and large-scale
magnetic field of V530 Per using the Zeeman-Doppler imaging method, assuming an
oblate stellar surface. We also estimate the short term evolution of the
brightness distribution through latitudinal differential rotation. Using the
same data set, we finally map the spatial distribution of prominences through
tomography of the H\alpha emission. The brightness map is dominated by a large,
dark spot near the pole, accompanied by a complex distribution of bright and
dark features at lower latitudes. The magnetic field map is reconstructed as
well, most of the large-scale magnetic field energy is stored in the toroidal
field component. The main radial field structure is a positive region of about
500 G, at the location of the dark polar spot. The brightness map of V530 Per
is sheared by solar-like differential rotation, with a roughly solar value for
the difference in rotation rate between the pole and equator. \halpha~is
observed in emission, and is mostly modulated by the stellar rotation period.
The prominence system is organized in a ring at the approximate location of the
co-rotation radius, with significant evolution between the two observing
nights. V530 Per is the first example of a solar-type star to have its surface
magnetic field and prominences mapped together, which will bring important
observational constraints to better understand the role of slingshot
prominences in the angular momentum evolution of the most active stars.

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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg