Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: V5852 Sgr: An Unusual Nova Possibly Associated with the Sagittarius
  Stream   We report spectroscopic and photometric follow-up of the peculiar nova
V5852~Sgr (discovered as OGLE-2015-NOVA-01), which exhibits a combination of
features from different nova classes. The photometry shows a flat-topped light
curve with quasi-periodic oscillations, then a smooth decline followed by two
fainter recoveries in brightness. Spectroscopy with the Southern African Large
Telescope shows first a classical nova with an Fe II or Fe IIb spectral type.
In the later spectrum, broad emissions from helium, nitrogen and oxygen are
prominent and the iron has faded which could be an indication to the start of
the nebular phase. The line widths suggest ejection velocities around
$1000\,{\rm km\,s^{-1}}$. The nova is in the direction of the Galactic bulge
and is heavily reddened by an uncertain amount. The $V$ magnitude 16 days after
maximum enables a distance to be estimated and this suggests that the nova may
be in the extreme trailing stream of the Sagittarius dwarf spheroidal galaxy.
If so it is the first nova to be detected from that, or from any dwarf
spheroidal galaxy. Given the uncertainty of the method and the unusual light
curve we cannot rule out the possibility that it is in the bulge or even the
Galactic disk behind the bulge.

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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: hep-lat