Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinematics of massive stars in the Small Magellanic Cloud   We present radial velocities for 2045 stars in the Small Magellanic Cloud
(SMC), obtained from the 2dF survey by Evans et al. (2004). The great majority
of these stars are of OBA type, tracing the dynamics of the young stellar
population. Dividing the sample into ad hoc `bar' and `wing' samples (north and
south, respectively, of the line: $\delta$ = -77$^{\circ}$50' + [4$\alpha$]',
where $\alpha$ is in minutes of time) we find that the velocities in the SMC
bar show a gradient of 26.3 +/- 1.6 km/s/deg. at a position angle of 126 +/- 4
deg. The derived gradient in the bar is robust to the adopted line of
demarcation between the two samples. The largest redshifts are found in the SMC
wing, in which the velocity distribution appears distinct from that in the bar,
most likely a consequence of the interaction between the Magellanic Clouds that
is predicted to have occurred 0.2 Gyr ago. The mean velocity for all stars in
the sample is +172.0 +/- 0.2 km/s (redshifted by ~20 km/s when compared to
published results for older populations), with a velocity dispersion of 30
km/s.

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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th