Violet-displaced absorption lines in the spectrum of the Wolf-Rayet star HD 151932

Abstract

Violet-displaced absorption components of Hei -Hen, N m -N v, and Civ have been found in the spectrum of the WN7 star HD 151932. The corresponding radial velocities increase with decreasing excitation potential of the originating ions, indicating a radially expanding atmosphere with accelerating velocity field. The velocity curves of the ions with lowest excitation potentials, He i and N in A4097, display a periodicity of about 3.5 days which leads to the concept of an oscillating outer envelope.