The importance of Wolf-Rayet ionization and feedback on super star cluster evolution

TL;DR

This study investigates how Wolf-Rayet stars influence the evolution and emergence of super star clusters by providing ionization and feedback, using multi-wavelength observations to identify their role in the transition from embedded to revealed states.

Contribution

It provides observational evidence that Wolf-Rayet stars may accelerate super star cluster emergence, highlighting their feedback role during a critical evolutionary phase.

Findings

Wolf-Rayet stars are present in embedded SSCs.

WR stars may accelerate cluster emergence.

Embedded SSCs with WR stars are in a short-lived evolutionary phase.

Abstract

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.