Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ISO observations of Hickson Compact Group 31 with the central Wolf-Rayet
  galaxy NGC 1741   Hickson Compact Group (HCG) 31, consisting of the Wolf-Rayet galaxy NGC 1741
and its irregular dwarf companions, was observed using the Infrared Space
Observatory. The deconvolved ISOCAM maps of the galaxies using the 7.7 micron
and 14.3 micron (LW6 and LW3) filters are presented, along with ISOPHOT
spectrometry of the central starburst region of NGC 1741 and the nucleus of
galaxy HCG 31A. Strong mid-IR emission was detected from the central burst in
NGC 1741, along with strong PAH features and a blend of features including [S
IV] at 10.5 micron. The 14.3/6.75 micron flux ratio, where the 6.75 micron flux
was synthesized from the PHT-S spectrum, and 14.3/7.7 micron flux ratios
suggest that the central burst within NGC 1741 may be moving towards the
post-starburst phase. Diagnostic tools including the ratio of the integrated
PAH luminosity to the 40 to 120 micron infrared luminosity and the far-infrared
colours reveal that despite the high surface brightness of the nucleus, the
properties of NGC 1741 can be explained in terms of a starburst and do not
require the presence of an AGN. The Tycho catalogue star TYC 04758-466-1, with
m$_{V}$ = 11.3 and spectral type F6, was detected at 7.7 and 14.3 microns.

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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: patt-sol