SIMBAD references

Evolutionary models allow an assignment of both a mass and a luminosity to a Wolf-Rayet (WR) star in a cluster, and hence allow a determination of the Bolometric Correction (B.C.). We plot all cluster WR stars in the M_v,logM/M_☉ diagram of Smith & Maeder (1989); this more than doubles the number of stars and extends the subclasses represented to include WN4.5, WC9 and WO2. The same method applied to WR stars in associations yields large uncertainties but includes useful limits on subclasses not represented in clusters: WN2, 3 and 8 and WC 5 and 6. The increased sample and expanded subclass range give a discrimination in the B.C. that was not previously possible. The B.C.'s derived for WN stars range from -4.0 to -6.0 with the expected trend of larger values for stars with higher excitation spectra. For WC stars, there is little evidence for a similar trend; most observations presented here are consistent with B.C.=-4.5, as before. The convergence of B.C. values derived from evolutionary and atmospheric models is extremely satisfactory, giving increased confidence in both methods.