Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinematics and binaries in young stellar aggregates   Internal kinematics, spectroscopic binaries and galactic motion are
investigated for the trapezium system BD+00.1617 (which lies at the heart of
the young open cluster Bochum 2) by means on 73 high resolution Echelle+CCD
spectra secured over the period 1994-98. Two of the three O-type member stars
are found to be binaries on close and highly eccentric orbits of 6.8 and 11.0
day period. The spectra of the two binaries show large variations in the
half-intensity and equivalent widths of the HeI absorption lines, which are
intrinsic to the primaries and are not correlated to the orbital phase.
Astrometric and radial velocities exclude that one of the component is leaving
as a runaway star, but upper limits are still compatible with the trapezium
evaporating at very low relative velocities. The projected rotational
velocities of the three constituent O--type stars are low. This conforms to
expectations from the high frequency of binaries. The observed radial velocity
of Bochum 2 agrees with the Hron (1987) expression for the Galaxy rotation
inside the latter's quoted errors.

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The categories of this paper are: eess
3
The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org