Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Luminous Starburst Ring in NGC 7771: Sequential Star Formation?   Only two of the twenty highly luminous starburst galaxies analyzed by Smith
et al. exhibit circumnuclear rings of star formation. These galaxies provide a
link between 10^11 L_sun systems and classical, less-luminous ringed systems.
We report the discovery of a near-infrared counterpart to the nuclear ring of
radio emission in NGC 7771. A displacement between the ~10 radio bright clumps
and the ~10 near-infrared bright clumps indicates the presence of multiple
generations of star formation. The estimated thermal emission from each radio
source is equivalent to that of ~35000 O6 stars. Each near-infrared bright knot
contains ~5000 red supergiants, on average. The stellar mass of each knot is
estimated to be ~10^7 M_sun. The implied time-averaged star formation rate is
\~40 M_sun per yr. Several similarities are found between the properties of
this system and other ringed and non-ringed starbursts. Morphological
differences between NGC 7771 and the starburst + Seyfert 1 galaxy NGC 7469
suggest that NGC 7771 may not be old enough to fuel an AGN, or may not be
capable of fueling an AGN. Alternatively, the differences may be unrelated to
the presence or absence of an AGN and may simply reflect the possibility that
star formation in rings is episodic.

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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th