Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Evolution of the ISM in the Mildly Disturbed Spiral Galaxy NGC 4647   We present matched-resolution maps of HI and CO emission in the Virgo Cluster
spiral NGC 4647. The galaxy shows a mild kinematic disturbance in which one
side of the rotation curve flattens but the other side continues to rise. This
kinematic asymmetry is coupled with a dramatic asymmetry in the molecular gas
distribution but not in the atomic gas. An analysis of the gas column densities
and the interstellar pressure suggests that the H2/HI surface density ratio on
the east side of the galaxy is three times higher than expected from the
hydrostatic pressure contributed by the mass of the stellar disk. We discuss
the probable effects of ram pressure, gravitational interactions, and
asymmetric potentials on the interstellar medium and suggest it is likely that
a m=1 perturbation in the gravitational potential could be responsible for all
of the galaxy's features. Kinematic disturbances of the type seen here are
common, but the curious thing about NGC 4647 is that the molecular distribution
appears more disturbed than the HI distribution. Thus it is the combination of
the two gas phases that provides such interesting insight into the galaxy's
history and into models of the interstellar medium.

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The categories of this paper are: q-bio
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The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
1
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: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas