Answers are grounded in this paper and cite their sources.
The authors have monitored the five bright Cygnus WN stars in the unblended He II λ5411 emission line at high spectral resolution and high signal-to-noise ratio during four or five nights. Typical data are presented here for the two single WN6 stars HD 191765 and HD 192163. The spectra reveal narrow emission bumps superposed on a broad, smooth background wind profile, with FWHM ≈ 2 - 10 Å and height ≤10% in continuum units for HD 191765. The bumps always appear to accelerate outward along with the general wind, on a time scale of hours.
No takes yet. Share an insight, caveat, or question.
Moffat et al. (1988) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: