Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: MHD Stellar and Disk Winds: Application to Planetary Nebulae   MHD winds can emanate from both stars and surrounding accretion disks. It is
of interest to know how much wind power is available and which (if either) of
the two rotators dominates that power. We investigate this in the context of
multi-polar planetary nebulae (PNe) and proto-planetary nebulae (PPNe), for
which recent observations have revealed the need for a wind power source in
excess of that available from radiation driving, and a possible need for
magnetic shaping. We calculate the MHD wind power from a coupled disk and star,
where the former results from binary disruption. The resulting wind powers
depend only on the accretion rate and stellar properties. We find that if the
stellar envelope were initially slowly rotating, the disk wind would dominate
throughout the evolution. If the envelope of the star were rapidly rotating,
the stellar wind could initially be of comparable power to the disk wind until
the stellar wind carries away the star's angular momentum. Since an initially
rapidly rotating star can have its spin and magnetic axes misaligned to the
disk, multi-polar outflows can result from this disk wind system. For times
greater than a spin-down time, the post-AGB stellar wind is slaved to the disk
for both slow and rapid initial spin cases and the disk wind luminosity
dominates. We find a reasonably large parameter space where a hybrid star+disk
MHD driven wind is plausible and where both or either can account for PPNe and
PNe powers. We also speculate on the morphologies which may emerge from the
coupled system. The coupled winds might help explain the shapes of a number of
remarkable multi-shell or multi-polar nebulae. Magnetic activity such as X-ray
flares may be associated with the both central star and the disk and would be a
valuable diagnostic for the dynamical role of MHD processes in PNe.

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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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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: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: physics
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The categories of this paper are: hep-lat