1995A&A...302..457C

A detailed study of 3 `weak-lined' Galactic WN3-4 stars (WR46=HD104994, WR128=HD187282 and WR152=HD211564) has been carried out based on new ultraviolet, optical and infrared spectroscopy. Tailored analyses, using the WR standard model, allow determinations of stellar parameters and chemical abundances based on the observed hydrogen, helium, carbon, nitrogen and oxygen spectrum, leading to higher stellar temperatures and luminosities than previously thought. We find that the temperatures (50-90kK) and luminosities (log L/L_☉=4.8-5.5) of our weak-lined WNE sample lie close to the strong-lined WNE's, but with mass-loss rates over an order of magnitude lower (log {dot}(M)/M_☉/yr~-5.2) leading to smaller atmospheric extensions. Fairly low luminosities (10⁵L_☉) are found for WR128 and WR152 although hydrogen is clearly present (around 10% by mass). Such WR stars are not currently predicted by single star evolutionary theory, while close binary evolution may provide a possible explanation. For these objects, metal abundances are consistent with CNO-equilibrium values (N/He≃0.004, C/N≃0.05, C/O≃1), while an unusual oxygen abundance is found for WR46 (N/He≃0.006, O/N≃0.1, C/O<0.3). Our results support the Population I WR nature of WR46 (with a possible compact companion) rather than a low mass X-ray binary, as has been suggested.