Per. - From the ratios 4045: H and 4226: H and the intensity of the G band a spectral type of F6 is derived on the system of the present Atlas. The following features indicate that the spectrum in the blue region comes from two stars.
1. The CN absorption, having a sharp head at 4215, is present and is about as strong as in a giant G2 star. This absorption was not seen in any normal star earlier than G0 examined while preparing the Atlas.
2. There is a broad, faint absorption at H which makes the appearance of the region different from that in a normal F6 star. This is probably due to a broad A-type hydrogen line superposed on the narrower one.
3. The strongest absorption at K is narrow and is similar to a star near type A5, and there is almost certainly present a faint, broad K line superposed on the sharp one.
The spectral type of the component of later type is probably near G5. Its luminosity class is probably III.
a Equ. - The spectrum is similar to Per. The CN absorption toward the violet from 4215 is present and indicates that the later-type spectrum is near G5. The integrated spectral type at 4000-4300 is somewhat earlier than Per - about F5 - owing to the greater strength of the H lines. The A star appears to be somewhat brighter relative to the later-type component. The line at 4077 is stronger relative to 4045 than in Per.
Leo. - The CN absorption near 4215 is not observed and the later-type spectrum is therefore almost certainly earlier than G0. This spectrum is combined with one of early type which, to judge by the narrow K line, is near class A2. The two components form a spectroscopic binary. The spectrograms used were obtained on April 22, 1942; on them the K line is composite, the sharp A component lying near the red edge of a faint, diffuse component. The line 4077 is strong, and from its intensity a similarity in luminosity to an F supergiant [a Per (F5) or Cyg (F8)] might be assumed. The region of the G band, however, does not have an appearance like that of a supergiant of type F, and other line ratios suggest a luminosity class of around II-III. This value is uncertain; it could be determined more accurately if spectrograms on a high-contrast emulsion were available. The spectral type of the component of later type is probably near F6.
a Aur. - The combined spectral type of the two components is G2 II-III. An unpublished determination made several years ago from high-dispersion plates on which the components were resolved gives, on the system of the present Atlas,
The separate values for the two components are very uncertain and may be in error by a considerable fraction of their separation.
Cyg. - The spectral type of the component of late type is probably K3 II. At the position of K there is a broad, shallow absorption. It is estimated that the spectral type of the component of early type is probably earlier than A0. The features described all belong to the spectrum of Cyg A.