Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NICMOS Observations of Interaction Triggered Star Formation in the
  Luminous Infrared Galaxy NGC 6090   High resolution, 1.1, 1.6, and 2.2 micron imaging of the luminous infrared
galaxy NGC 6090 obtained with NICMOS of the Hubble Space Telescope are
presented. These new observations are centered on the two nuclei of the merger,
and reveal the spiral structure of the eastern galaxy and the amorphous nature
of the western galaxy. The nuclear separation of 3.2 kpc (H_0 = 75 km/s/Mpc)
indicates that NGC 6090 is at an intermediate stage of merging. Bright
knots/clusters are also visible in the region overlapping the merging galaxies;
four of these knots appear bluer than the underlying galaxies and have colors
consistent with young (<~ 10^7 yr) star clusters. The spatial coincidence of
the knots with the molecular gas in NGC 6090 indicates that much of the present
star formation is occuring outside of the nuclear region of merging galaxies,
consistent with recent studies of other double nuclei luminous infrared
galaxies.

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The categories of this paper are: mtrl-th
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: cs
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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: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex