A radial-velocity study of 18 emission-line B stars

A total of 647 radial velocities of 18 northern-hemisphere Be stars obtained over two observing seasons (1983–1985) are presented. These velocities have been determined by the cross-correlation technique applied to selected spectral regions avoiding the hydrogen lines and including the He I lines. Analyses of these data via Fourier techniques suggest that three new spectroscopic binaries are discovered and that seven stars show variability in radial velocity which may be attributable to radial or non-radial pulsation. Four known binary orbits are confirmed. Only four stars in the sample are found to have constant radial velocity. These results strengthen and extend the evidence that the Be phenomenon can result from pulsational instability and that the proportion of binary systems among Be stars is about the same as the normal stellar population. Very-high-resolution spectroscopy of those stars found to be variable in velocity should reveal changes in line-profile shape due to non-radial pulsation.