The interplay between the young stellar super cluster Westerlund 1, and the surrounding interstellar medium

We analyze the multi-band (CO, HI and Spitzer maps), large-scale (150 pc) gaseous structure around Westerlund 1, the most massive known superstar cluster in the Milky Way, with the intention of exploring the effect of feedback from massive stars in this young (age < 5 Myr) cluster on the surrounding interstellar medium. We find no traces of the parental molecular cloud in the immediate vicinity of the cluster, instead this volume is partially filled by HI gas. On the other hand, there are two giant molecular clouds, both moving away from the cluster at 5–10 km s−1, at distances of around 50–150 pc. There are several ultra-compact HII regions associated with these giant molecular clouds. All these events suggest that the cluster has played an important role in re-structuring the ISM, in the form of ejecting the molecular gas, as well as triggering secondary star formation.