Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: IFU spectroscopy of southern PN VI: The extraordinary chemo-dynamics of
  Hen 2-111   In this paper we present integral field spectroscopy of the extraordinary
Type I bipolar planetary nebula Hen 2-111. In the lobes we map fast moving
knots of material with [N II]$\lambda 6584$/H$\alpha$ ratios up to 12, and with
radial velocities relative to systemic from -340 km/s up to +390 km/s. We find
evidence of a bipolar ejection event at a velocity $\sim 600$ km/s from the
central star (assumed to be a binary), which occurred about 8000yr ago. The
fast moving material is chemically quite distinct from the lower velocity gas
in the bipolar lobes., and displays very high N abundances. We show that the
fast moving N-rich knots are not photoionised by the central star, and have
constructed detailed shock models for the brightest knot. We find a pre-shock
density $\sim 6$cm$^{-3}$, and a shock velocity $\sim150$ km/s. The shock is
not fully radiative, being only $\sim 600$yr old. This shocked gas is partially
H-burnt, with a helium abundance by mass exceeding that of hydrogen, and is
interacting with partially H-burnt material ejected in an earlier episode of
mass loss. We conclude that the high-velocity material and the bipolar shell
must have originated during the late stages of evolution of a common-envelope
phase in a close binary system.

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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex