Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: IC4663: the first unambiguous [WN] Wolf-Rayet central star of a
  planetary nebula   Several [WC]-type central stars of planetary nebulae (PNe) are known to mimic
the spectroscopic appearance of massive carbon-rich or WC-type Wolf-Rayet
stars. In stark contrast, no [WN]-type central stars have yet been identified
as clear-cut analogues of the common nitrogen-rich or WN-type Wolf-Rayet stars.
We have identified the [WN3] central star of IC4663 to be the first unambiguous
example in PNe. The low luminosity nucleus and an asymptotic giant branch (AGB)
halo surrounding the main nebula prove the bona-fide PN nature of IC4663. Model
atmosphere analysis reveals the [WN3] star to have an exotic chemical
composition of helium (95%), hydrogen (<2%), nitrogen (0.8%), neon (0.2%) and
oxygen (0.05%) by mass. Such an extreme helium-dominated composition cannot be
predicted by current evolutionary scenarios for hydrogen deficient [WC]-type
central stars. Only with the discovery of IC4663 and its unusual composition
can we now connect [WN] central stars to the O(He) central stars in a second
H-deficient and He-rich evolutionary sequence, [WN]->O(He), that exists in
parallel to the carbon-rich [WC]->PG1159 sequence. This suggests a simpler
mechanism, perhaps a binary merger, can better explain H-deficiency in PNe and
potentially other H-deficient/He-rich stars. In this respect IC4663 is the best
supported case for a possible merged binary central star of a PN.

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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
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The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph