The very bright and compact massive young cluster , NGC 3603 , has been cited as an example of a starburst in the Milky Way and compared with the much-studied R136/30 Doradus region in the Large Magellanic Cloud .
Here we build on the discovery by [ ] of a large number of reddened O stars around this cluster .
We construct a list of 288 candidate O stars with proper motions , in a region of sky spanning 1.5 \times 1.5 square degrees centered on NGC 3603 , by cross-matching the Mohr-Smith et al .
( 2017 ) catalogue with Gaia DR2 \citep Gaiadr2 .
This provides the basis for a first comprehensive examination of the proper motions of these massive stars in the halo of NGC 3603 , relative to the much better studied central region .
We identify up to 11 likely O star ejections – 8 of which would have been ejected between 0.60 and 0.95 Myr ago ( supporting the age of \sim 1 Myr that has been attributed to the bright cluster centre ) .
Seven candidate ejections are arranged in a partial ring to the south of the cluster core spanning radii of 9–18 arcmin ( 18–36 pc if the cluster is 7 kpc away ) .
We also show that the cluster has a halo of a further \sim 100 O stars extending to a radius of at least 5 arcmin , adding to the picture of NGC 3603 as a scaled down version of the R136/30 Dor region .