10. The Spectrum of Draconis

From the lines of He I, Mg II, and Si II the spectral type would be judged to be B8. The Balmer lines are very peculiar; they are weak but do not have the sharp-edged appearance associated with high luminosity. A superficial examination might indicate that the star belongs in luminosity class II at B8. A comparison with the A0 Ib star Leo shows, however, that the shape of the Balmer lines - in particular H and H - is not similar to a high-luminosity star; the contours of the H lines are more nearly like those in an early B-type dwarf.

The trigonometric parallax of Dra is 0".039 ± 7 (two modern determinations). The absolute magnitude is probably fainter than zero, and it is likely that the star lies somewhat below the main sequence.