The Intensities of Stellar Absorption Lines

The intensities of stellar absorption lines have been measured in the spectra of a Canis Majoris, a Lyrae, a Cygni, a Persei, Aurigae and i ~ Leporis. With the help of theoretical multiplet intensities, curves have been constructed, for each star separately, showing the relation between total absorption and number of atoms. These curves differ considerably. All parts of the curves lie between the limits A = Const. and A o N. An application of the theory of Schütz based upon the simultaneous effects of radia- tion damping and thermal Doppler broadening shows agreement with the observations in a Canis Majoris, a Lyrae, and a Cygni, provided, however, the damping constant is assumed to be ten times that given by the classical theory. For the remaining three stars the hypothesis is advanced that in their atmospheres turbulent motions far exceed the motions caused by thermal agitation. The theory of Schütz is enlarged to include the case of turbulent motions, and excellent agreement with the observations is found. The most probable turbulent velocity is found to be 67 km/sec. in i~ Leporis, 20 km/sec. in Aurigae, and 7 km/sec. in a Persei. The interpretation of many other observational data in the light of the turbulence hypothesis is briefly discussed