Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetism, rotation, and nonthermal emission in cool stars -- Average
  magnetic field measurements in 292 M dwarfs   Stellar dynamos generate magnetic fields that are of fundamental importance
to the variability and evolution of Sun-like and low-mass stars, and for the
development of their planetary systems. We report measurements of
surface-average magnetic fields in 292 M dwarfs from a comparison with
radiative transfer calculations; for 260 of them, this is the first measurement
of this kind. Our data were obtained from more than 15,000 high-resolution
spectra taken during the CARMENES project. They reveal a relation between
average field strength, <B>, and Rossby number, $Ro$, resembling the
well-studied rotation-activity relation. Among the slowly rotating stars, we
find that magnetic flux, $\Phi_\textrm{B}$, is proportional to rotation period,
$P$, and among the rapidly rotating stars that average surface fields do not
grow significantly beyond the level set by the available kinetic energy.
Furthermore, we find close relations between nonthermal coronal X-ray emission,
chromospheric H$\alpha$ and Ca H&K emission, and magnetic flux. Taken together,
these relations demonstrate empirically that the rotation-activity relation can
be traced back to a dependence of the magnetic dynamo on rotation. We advocate
the picture that the magnetic dynamo generates magnetic flux on the stellar
surface proportional to rotation rate with a saturation limit set by the
available kinetic energy, and we provide relations for average field strengths
and nonthermal emission that are independent of the choice of the convective
turnover time. We also find that Ca H&K emission saturates at average field
strengths of $\langle B \rangle \approx 800$ G while H$\alpha$ and X-ray
emission grow further with stronger fields in the more rapidly rotating stars.
This is in conflict with the coronal stripping scenario predicting that in the
most rapidly rotating stars coronal plasma would be cooled to chromospheric
temperatures.

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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th