A DETAILED STUDY OF A VERY LATE WN STAR IN M33

We present the first quantitative analysis of a M 33 Wolf-Rayet star, the Ofpe/WN9 candidate MCA1-B (Willis et al. 1992). From new higher re solution observations analysed with the Wolf-Rayet standard model, we reclassify MCA1-B as WN9 and find its stellar parameters (T=29kK, T-ef f=19kK, log L/L.=5.8, log M/M. yr(-1)=-4.0, upsilon(infinity)=420 km s (-1))to be very similar to the LMC WN9 stars (Crowther et al. 1995a), and R84 in particular. Chemical abundances (H/He=2.6, N/He=0.003, C/N< 0.1) are also comparable to R84 indicating a similar evolutionary stat us (probable dormant LBV) and metallicity (Z similar to 0.008) consist ent with its location in the outer regions of M 33.