Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Seismic evidence for near solid-body rotation in two Kepler subgiants
  and implications for angular momentum transport   Asteroseismic measurements of the internal rotation of subgiants and red
giants all show the need for invoking a more efficient transport of angular
momentum than theoretically predicted. Constraints on the core rotation rate
are available starting from the base of the red giant branch (RGB) and we are
still lacking information on the internal rotation of less evolved subgiants.
We identified two young Kepler subgiants, KIC8524425 and KIC5955122, whose
mixed modes are clearly split by rotation. Using the full Kepler data set, we
extracted the mode frequencies and rotational splittings for the two stars
using a Bayesian approach. We then performed a detailed seismic modeling of
both targets and used the rotational kernels to invert their internal rotation
profiles. We found that both stars are rotating nearly as solid bodies, with
core-envelope contrasts of $\Omega_{\rm g}/\Omega_{\rm p}=0.68\pm0.47$ for
KIC8524425 and $0.72\pm0.37$ for KIC5955122. This result shows that the
internal transport of angular momentum has to occur faster than the timescale
at which differential rotation is forced in these stars (between 300 Myr and
600 Myr). By modeling the additional transport of angular momentum as a
diffusive process with a constant viscosity $\nu_{\rm add}$, we found that
values of $\nu_{\rm add}>5\times10^4$~cm$^2$.s$^{-1}$ are required to account
for the internal rotation of KIC8524425, and $\nu_{\rm
add}>1.5\times10^5$~cm$^2$.s$^{-1}$ for KIC5955122. These values are lower than
or comparable to the efficiency of the core-envelope coupling during the main
sequence, as given by the surface rotation of stars in open clusters. On the
other hand, they are higher than the viscosity needed to reproduce the rotation
of subgiants near the base of the RGB. Our results yield further evidence that
the efficiency of the internal redistribution of angular momentum decreases
during the subgiant phase.

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The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: stat
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg