The method for measuring broad, shallow features in white dwarf spectra is described. Unidentified bands in AC+7008247, W 219, and L 879-14 are illustrated in Figures 1-3. Broad, very shallow lines of He 1 are found in HZ 29, a probable white dwarf, and illustrated in Figure 4.
No takes yet. Share an insight, caveat, or question.
Greenstein et al. (1957) studied this question.