Colour changes in mid-B star variables.

Model predictions of light changes due to nonradial stellar pulsation have been compared with the observations of light and color changes in mid-B star variables made by Waelkens and Rufener (1985). It is concluded that these observations are consistent with the presence of low-l (dipole and quadrupole) nonradial pulsations in the stars. This strengthens Waelkens and Rufener's hypothesis that these variables may be identified with the 53 Persei stars. The differences between the model predictions for these large-Q variables, which have periods in the 1 to 3 day range, and the predictions of small-Q models, which apply to Beta Cephei variables, are explained.