Figure 3 [plate 3] shows the spectrum of the WN star HD 192163, together with the Of star Cephei (the plate has been adapted from plate 2 of the Morgan, Abt, and Tapscott Atlas of 1978). The normal position of He I 3888 has been marked by small black triangles; the radial velocity of the strong, shifted absorption line in HD 192163 is - 1,400 km/s. One WN star, HD 191765, shows a somewhat weaker 3888 at a radial velocity of 1,600 km/s.
There are also B-type stars showing this same, blue-shifted absorption line. Merrill (1951) has observed multiple absorption components of He I 3888 in BD + 11°4673; as many as eight components were observed with radial velocities covering the range - 36 to - 428 km/s. The components vary rapidly in position and intensity, and comprise a spectacular example of stellar winds.
The strongest absorption line in the spectrum of the Be star RY Scuti = HD 169515 is He I 3888, and it may be another example of the stellar-wind line.