The importance of Wolf-Rayet ionization and feedback on super star
  cluster evolution
  The feedback from massive stars is important to super star cluster (SSC)
evolution and the timescales on which it occurs. SSCs form embedded in thick
material, and eventually, the cluster is cleared out and revealed at optical
wavelengths -- however, this transition is not well understood. We are
investigating this critical SSC evolutionary transition with a multi-wavelength
observational campaign. Although previously thought to appear after the cluster
has fully removed embedding natal material, we have found that SSCs may host
large populations of Wolf-Rayet stars. These evolved stars provide ionization
and mechanical feedback that we hypothesize is the tipping point in the
combined feedback processes that drive a SSC to emerge. Utilizing optical
spectra obtained with the 4m Mayall Telescope at Kitt Peak National Observatory
and the 6.5m MMT, we have compiled a sample of embedded SSCs that are likely
undergoing this short-lived evolutionary phase and in which we confirm the
presence of Wolf-Rayet stars. Early results suggest that WRs may accelerate the
cluster emergence.
