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Masses and M/L Ratios of Bright Globular Clusters in NGC 5128

Published online by Cambridge University Press:  01 September 2007

M. Rejkuba
Affiliation:
ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany email: mrejkuba@eso.org
P. Dubath
Affiliation:
Observatoire de Geneve, ch. des Maillettes 51, 1290 Sauverny, Switzerland
D. Minniti
Affiliation:
Pontificia Univ. Católica de Chile, Vicuña Mackenna 4860, Santiago 22, Chile
G. Meylan
Affiliation:
Ecole Polytechnique Fédérale de Lausanne, Observatoire, 1290 Sauverny, Switzerland
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Abstract

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We present an analysis of the radial velocities and velocity dispersions for 27 bright globular clusters in the nearby elliptical galaxy NGC 5128 (Centaurus A). For 22 clusters we combine our new velocity dispersion measurements with the information on the structural parameters, either from the literature when available or from our own data, in order to derive the cluster masses and mass-to-light (M/L) ratios. The masses range from 1.2 × 105M, typical of Galactic globular clusters, to 1.4 × 107M, similar to more massive dwarf globular transition objects (DGTOs) or ultra compact dwarfs (UCDs) and to nuclei of nucleated dE galaxies. The average M/LV is 3±1, larger than the average M/LV of globular clusters in the Local Group galaxies. The correlations of structural parameters, velocity dispersion, masses and M/LV for the bright globular clusters extend the properties established for the most massive Local Group clusters towards those characteristic of dwarf elliptical galaxy nuclei and DGTOs/UCDs. The detection of the mass-radius and the mass-M/LV relations for the globular clusters with masses greater than ~ 2 × 106M provides the link between “normal” old globular clusters, young massive clusters, and evolved massive objects.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2008

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