Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HI Spatial Distribution in the Galaxy NGC 3783   We have mapped the emission from atomic hydrogen at 21 cm from the galaxy NGC
3783 with the Australia Telescope Compact Array. Our main results are: a) the
HI morphology is irregular and perturbed, gathered in three blobs apparently
unrelated to the optical morphology; b) the observed HI velocity distribution
indicates a normal disk in differential rotation with a constant velocity out
to a radius of 160'' (30 kpc), c) the inclination of the disk is about 25 deg
with the kinematic major axis at a position angle slightly different from that
of the stellar bar, d) the HI mass inside a radius of 18'' is only 2.1 10^7
Msun, the total HI mass within 180'' is 1.1 10^9 Msun and the dynamical mass is
2 10^{11} Msun. The bulk of the gas in NGC 3783 is outside the diameter of the
stellar bar; e) Numerical simulations of the gas flow in the barred potential
derived from the red image indicate that the pattern speed is Omega_p = 38
km/s/kpc: the ring of Halpha emitting regions encircling the bar would then
correspond to UHR, and the Halpha accumulation in the center to a nuclear ring.
Various possibilities are discussed to account for the active nucleus fuelling.

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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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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: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: physics
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: cs
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The categories of this paper are: stat