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If binaries are common among massive stars, it will have important consequences for the derivation of fundamental properties like the cluster age, IMF and dynamical mass. Making use of the multiplexing facilities of Gemini Multi Object Spectrograph (GMOS) we were able to investigate the presence of binary stars within the ionising cluster of 30 Doradus. From a seven epochs observing campaign at Gemini South we detect a binary candidate rate of about 50%, which is consistent with an intrinsic 100% binary rate among massive stars. We find that single epoch determinations of the velocity dispersion give values around 30 km/s . After correcting the global velocity dispersion for the binary orbital motions, the true cluster velocity dispersion is 8.3 km/s. This value implies a virial mass of about 4.5E5 Msun or 8 percent of the mass calculated using the single epoch value. The binary corrected virial mass estimate is consistent with photometric mass determinations thus suggesting that NGC 2070 is a firm candidate for a future globular cluster.
The Dragonfish Nebula has been recently claimed to be powered by a superluminous but elusive OB association. Instead, systematic searches in near-infrared photometric surveys have found many other cluster candidates on this sky region. Among these, t
This paper presents deep high quality photometry of globular cluster (GC) systems belonging to five early-type galaxies covering a range of mass and environment. Photometric data were obtained with the Gemini North and Gemini South telescopes in the
We present a technique to extract ultra-deep diffuse-light spectra from the standard multi-object spectroscopic observations used to investigate extragalactic globular cluster (GC) systems. This technique allows a clean extraction of the spectrum of
We present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 squ. deg. of th
We present a phase-resolved, optical, spectroscopic study of the eclipsing low-mass X-ray binary, EXO 0748-676 = UY Vol. The sensitivity of Gemini combined with our complete phase coverage makes for the most detailed blue spectroscopic study of this