1995A&A...301..213M

There are a number of lines in the spectrum of P Cygni which cannot be identified by the use of the "Revised Multiplet Table" (Moore 1959) and some other sources like "Table of spectral lines" (Zaidel et al. 1977), the work of Glad (1956) etc. The most prominent among them is the line at λ∼3649A. It consists of an emission and shortward displaced absorption component, i.e. it shows a P Cyg-type profile. The absorption radial velocity and the obtained rough estimate of the total excitation energy place the line in nearly the same parts of the wind where the medium-strength He i lines arise. The 3649A line is not observed in the spectrum of normal B0 to B3 supergiants of luminosity classes Ia and Ib.