*4.2. Integrated WR Populations*

Distant starburst galaxies (by "distant" we means not resolved into stars) often display a WR "bump" in their optical spectra at rest wavelengths of 4650–4670 Å, due to a mixture of WN and WC stars in the integrated spectrum. The first such system was identified in the compact dwarf He 2–10 [119]; quantitative analysis in theory allows one to derive the relative number of WR and O stars [120]; for a more on this subject, see [121] and other papers in their series.

Sokal and collaborators detected the WR bump in an emerging "super star clusters," massive clusters which are just now clearing out their natal material, demonstrating that the time to clear out such material is comparable to the time it takes for massive stars to evolve to the WR phase (∼3 Myr) [122,123].
