late WN stars. The terminal wind velocity we adopt is  = 840 [km s$^{-1}$]{}, as found by Herald et al. (2001) for the WN8 star WR40. The abundances were taken from Table 9 in Herald et al. (2001). Note the relatively high nitrogen abundance, as typical for WN stars of course, and the high helium abundance, $Y$ = 0.83 (by mass). As helium is not [*directly*]{} relevant for the line driving at galactic metallicities (although this changes at lower $Z$; Vink 2000), it may well be the case that the mass-loss metallicity dependence for these stars is similar to that of O stars.

[ccc]{}

Parameter & WN & WC\
 (K) & 40000 & 40000\
  & 5.62 & 5.36\
$M$ () & 20 & 10\
 ([km s$^{-1}$]{})& 840 & 1200\
X & 0.15 & –\
Y & 0.83 & 0.5\
C & – & 0.5\
log () & $-$4.89 & $-$5.34\

We first note that WC stars are believed to be He burning stars, theoretically expected to lie on the He-main sequence with large surface temperatures (in excess of 100 000 K). Observationally, significantly lower effective temperatures are seen, presumably due to large amounts of mass loss at Galactic metallicity. We 