Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamics of the Young Binary LMC Cluster NGC 1850   In this paper we have examined the age and internal dynamics of the young
binary LMC cluster NGC 1850 using BV CCD images and echelle spectra of 52
supergiants. Isochrone fits to a BV color-magnitude diagram revealed that the
primary cluster has an age of $\tau = 90 \pm 30$ Myr while the secondary member
has $\tau = 6 \pm 5$ Myr. BV surface brightness profiles were constructed out
to R $>$ 40 pc, and single-component King-Michie (KM) models were applied. The
total cluster luminosity varied from L$_B$ = 2.60 - 2.65 $\times 10^6$
L$_B$\sol\ and L$_V$ = 1.25 - 1.35 $\times 10^6$ as the anisotropy radius
varied from infinity to three times the scale radius with the isotropic models
providing the best agreement with the data. Of the 52 stars with echelle
spectra, a subset of 36 were used to study the cluster dynamics. The KM radial
velocity distributions were fitted to these velocities yielding total cluster
masses of 5.4 - 5.9 $\pm 2.4 \times 10^4$ M\sol\ corresponding to M/L$_B$ =
0.02 $\pm 0.01$ M\sol/L$_B$\sol\ or M/L$_V$ = 0.05 $\pm 0.02$ M\sol/L$_V$\sol.
A rotational signal in the radial velocities has been detected at the 93\%
confidence level implying a rotation axis at a position angle of 100\deg. A
variety of rotating models were fit to the velocity data assuming cluster
ellipticities of $\epsilon = 0.1 - 0.3$. These models provided slightly better
agreement with the radial velocity data than the KM models and had masses that
were systematically lower by a few percent. The preferred value for the slope
of a power-law IMF is a relatively shallow, $x = 0.29 \pmm{+0.3}{-0.8}$
assuming the B-band M/L or $x = 0.71 \pmm{+0.2}{-0.4}$ for the V-band.

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The categories of this paper are: nlin
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
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The categories of this paper are: math