Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Changing Face of $\alpha$ Centauri B: Probing plage and stellar
  activity in K-dwarfs   A detailed knowledge of stellar activity is crucial for understanding stellar
dynamos, as well as pushing exoplanet radial-velocity detection limits towards
Earth analogue confirmation. We directly compare archival HARPS spectra taken
at the minimum in $\alpha$ Cen B's activity cycle to a high-activity state when
clear rotational modulation of $\log{R'_{HK}}$ is visible. Relative to the
inactive spectra, we find a large number of narrow pseudo-emission features in
the active spectra with strengths that are rotationally modulated. These
features most likely originate from plage, spots, or a combination of both.
They also display radial velocity variations of $\sim$300 m s$^{-1}$ -
consistent with an active region rotating across the stellar surface.
Furthermore, we see evidence that some of the lines originating from the
`active immaculate' photosphere appear broader relative to the `inactive
immaculate' case. This may be due to enhanced contributions of e.g. magnetic
bright points to these lines, which then causes additional line broadening.
More detailed analysis may enable measurements of plage and spot coverage using
single spectra in the future.

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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat