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 HD38268 ( catalog 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 ^ { -1 } .
After correcting the global velocity dispersion for the binary orbital motions , the “ true ” cluster velocity dispersion is 8.3 km s ^ { -1 } .
This value implies a virial mass of about 4.5 \times 10 ^ { 5 } M _ { \odot } 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 .