Resolving the low-mass content of Westerlund 1 using MCAO

Abstract : We present deep Ks band Gemini GeMS/GSAOI observations of Westerlund 1, the most massive young Galactic star cluster known. The high spatial resolution combined with a relatively stable point spread function across a large field of view provide unique possibilities to resolve the low-mass content of the cluster. We show that the clean point spread function is crucial in handling the source detection in this crowded field suffering extremely high contrast from the brightest hypergiants in the cluster to faint brown dwarfs.