Recent improvements in instrumentation now allows high
quality infrared stellar spectroscopy. Despite
only a tiny fraction of the luminosity of
W-R and related stars being emitted in the infrared, this region contains
extremely important wind diagnostic lines (e.g. HeI
2.058
m) and allows studies of objects which are too heavily
reddened to be observed at shorter wavelengths. For example,
many emission line objects lying close to the Galactic Centre
(Krabbe et al. 1991, 1995) show K-band spectra
similar to WNL stars. In order to verify whether IR spectroscopic
analyses are consistent with studies from optical observations
Crowther & Smith (1996a) performed a detailed analysis of two
WNE stars. Infrared profile fits to observations of HD191765 (WN6b)
are shown in Fig. 2.
Quantitative comparisons with previous optical and ultraviolet
studies confirmed the reliability of IR analyses, as
performed for several Galactic Centre stars by Krabbe et al. (1995).
Crowther & Smith (1996a) also confirmed the presence of hydrogen
in HD192163 (WN6b(h)), quite unprecedented for a hot WNE star
(Table 1).