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Description
We present the first results of an extensive photometric study of the most intrinsically variable Wolf-Rayet stars: the WN8 subclass. Some 375 individual differential observations of WR16 and WR40 were obtained over a contiguous interval of ~3 months in a narrow visual continuum bandpass. Over the same interval, we obtained roughly 200 broadband V observations of the fainter WN8 stars WR66 and WR82. All four WN8 stars show significant random variability on time scales of hours to ~a day -- probably related to the stochastic formation, propagation, and decay of emitting/scattering inhomogeneities in the winds. Unlike for WR66 and WR82, the photometric behaviour of WR16 and WR40 is more deterministic with ~two possible periods in the range ~2-30 days -- possibly related to some kind of LBV, binary, or rotation phenomenon. In addition, WR82 shows a possible secular decline during the 3 months and WR66 reveals a clear periodicity of 3.51 h. This short period may be related to nonradial pulsations or a spiral-in binary process invoking a low-mass, compact companion as seen in the massive x-ray binary Cyg X-3, a WN7 + c system of period 4.8 h.
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