Line Broadening in High-Luminosity Stars. II. Less Luminous Supergiants.

Several types of line broadening are considered for Ib supergiants Macroturbulence, in at least one likely form, gives profiles that are indistinguishable from rotational profiles. A magnetic field of 3800 gauss produces no broadening of X 4508 Fe ii but causes an apparent abundance increase of 38 per cent. Rotationally broadened profiles fit the observed ones and lead to a mean projected rotational velocity of 17 km/sec If conservation of angular momentum occurs, the rotational velocities are in accord with the evolution of Ib supergiants from early B dwarfs, provided that supergiants do not rotate as rigid bodies The rotational-velocity distributions of the recovered and present B dwarfs agree in maximum, mean, and general form. On the other hand, if conservation of angular momentum does not occur due to mass loss, this mass would not be readily apparent. We are not able to choose between these two pos -ibilities.