Variations in the Spectrum of Sigma Scorpii.
Abstract
During 19501951, 225 three-prism spectrograms of Scorp were obtained with the Mills spectrograph of the Lick Observatory. The radial velocities determined from the plates are connected by a period P2 = 0.246835 day. There is also a variation in the line width, which has a period identical with that of the radial velocity. On some nights, double lines appear at maximum or minimum velocity; when they are not double, they are asymmetric, and there is little doubt that they are composed of the blended double lines. As in 12 Lacertae, it is the alternation of these lines which results in the measurement of a variable radial velocity. There is a variation in the mean velocity with a period P5 33 days. The amplitude of the radial velocity-curve also varies, but it is uncertain whether this variation is periodic. This latter variation is strongly correlated with a variation in the amplitude of the line-width curves. Struve's recent hypothesis for the p Cephei stars is considered in the light of the present investigation. The effect of a turbulent spot (the presence of which is fundamental in the hypothesis) on the line profile is examined. If one takes (from the theory of the curve of growth) the equivalent line width in the turbulent spot to be three times that in the quiescent area (both per unit area), one finds that, for a symmetrical spot of radius half the radius of the star, the effect will be clearly marked.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1952
- DOI:
- 10.1086/145555
- Bibcode:
- 1952ApJ...115..402L