Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: WFPC2 Observations of NGC 454: an Interacting Pair of Galaxies   We present WFPC2 images in the F450W, F606W and F814W filters of the
interacting pair of galaxies NGC 454. Our data indicate that the system is in
the early stages of interaction. A population of young star-clusters has formed
around the late component, and substantial amounts of gas have sunk into the
center of the earlier component, where it has not yet produced significant
visible star formation or nuclear activity. We have photometric evidence that
the star-clusters have strong line emission, which indicate the presence of a
substantial component of hot, massive stars which formed less than 5-10 Myrs
ago.

32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph