Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic flux transport on active cool stars and starspot lifetimes   We carry out numerical simulations of the surface evolution of bipolar
magnetic regions (BMRs) and magnetic spots on stars, which have radii and
surface rotational shears of AB Doradus, the Sun, and the HR 1099 primary. The
surface flux transport model is based on the magnetic induction equation for
radial fields under the effects of surface differential rotation, meridional
flow, and turbulent diffusion due to convective flow patterns. We calculate the
flux evolution and the lifetimes of BMRs and unipolar starspots, varying the
emergence latitude, surface shear rate, and tilt angle. For BMRs comparable to
the largest observed on the Sun, we find that varying the surface flows and the
tilt angle modifies the lifetimes over a range of one month. For very large
BMRs (area ~10% of the stellar surface) the assumption of a tilt angle
increasing with latitude leads to a significant increase of lifetime, as
compared to the case without tilt. Such regions can evolve to polar spots that
live more than a year. Adopting the observed weak latitudinal shear and the
radius of the active subgiant component of HR 1099, we find longer BMR
lifetimes as compared to the more strongly sheared AB Dor case. Random
emergence of six additional tilted bipoles in an activity belt at 60 degrees
latitude enhanced the lifetimes of polar caps up to 7 years. We have also
compared the evolution and lifetime of monolithic starspots with those of
conglomerates of smaller spots of similar total area. We find similar decay
patterns and lifetimes for both configurations.

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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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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: hep-ex
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The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci