Photometric variability of a complete sample of northern Wolf-Rayet stars.

At least half of a complete, magnitude-limited sample of northern W-R stars shows systematically modulated continuum light variability, of amplitude ≥0.02 mag. With the exception of the well-established binary W-R systems, the authors can make no definitive claims for the remaining stars as to the source of the variability among random wind fluctuations, pulsation or rotation effects, or phase-dependent binary modulations involving a wide O type companion or a close low-mass companion. Light variations of the well-known binaries can be accounted for by occultation effects and random wind variations. WN8 stars appear to show the highest level of random noise among W-R stars.