Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Abell 30 -- A Binary Central Star Among the Born-Again Planetary Nebulae   Eight planetary nebulae have been identified as `born-again', a class of
object typified by knotty secondary ejecta having low masses ($\sim$$10^{-4}$
M$_{\odot}$) with nearly no hydrogen. Abell 30, the archetype of the class,
also belongs to a small subset of planetary nebulae that exhibit extreme
abundance discrepancy factors (where Abell 30 is the most extreme), a
phenomenon strongly linked to binary star interactions. We report the presence
of light curve brightness variations having a period of 1.060 days that are
highly suggestive of a binary central star in Abell 30. If confirmed, this
detection supports the proposed link between binary central stars and extreme
abundance discrepancies.

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The categories of this paper are: eess
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th