EDP Sciences
Free access
Issue
A&A
Volume 380, Number 1, December II 2001
Page(s) 137 - 141
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20011427


A&A 380, 137-141 (2001)
DOI: 10.1051/0004-6361:20011427

The ionising cluster of 30 Doradus

IV. Stellar kinematics
G. Bosch1, 2, F. Selman3, J. Melnick3 and R. Terlevich1

1  Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
2  Facultad de Ciencias Astronómicas y Geofísica, La Plata, Argentina
3  European Southern Observatory, Alonso de Córdova 3107, Santiago, Chile

(Received 6 June 2001 / Accepted 4 October 2001 )

Abstract
On the basis of multislit spectroscopy of 180 stars in the ionising cluster of 30 Doradus we present reliable radial velocities for 55 stars. We calculate a radial velocity dispersion of ${\sim}35$ km s-1 for the cluster and we analyse the possible influence of spectroscopic binaries in this rather large velocity dispersion. We use numerical simulations to show that the observations are consistent with the hypothesis that all the stars in the cluster are binaries, and the total mass of the cluster is ~ $ 5 \times 10^{5}$ $M_\odot$. A simple test shows only marginal evidence for dynamical mass segregation which if present is most likely not due to dynamical relaxation.


Key words: stars: early-type -- stars: kinematics -- binaries: spectroscopic -- galaxies: clusters: general -- galaxies: Magellanic Clouds

Offprint request: G. Bosch, guille@fcaglp.unlp.edu.ar

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© ESO 2001