We present the results of a four-month , spectroscopic campaign of the Wolf-Rayet dust-making binary , WR137 .
We detect only small-amplitude , random variability in the C iii \lambda 5696 emission line and its integrated quantities ( radial velocity , equivalent width , skewness , kurtosis ) that can be explained by stochastic clumps in the wind of the WC star .
We find no evidence of large-scale , periodic variations often associated with Corotating Interaction Regions that could have explained the observed intrinsic continuum polarization of this star .
ÕOur moderately high-resolution and high signal-to-noise average Keck spectrum shows narrow double-peak emission profiles in the H \alpha , H \beta , H \gamma , He ii \lambda 6678 and He ii \lambda 5876 lines .
These peaks have a stable blue-to-red intensity ratio with a mean of 0.997 and a root-mean-square of 0.004 , commensurate with the noise level ; no variability is found during the entire observing period .
We suggest that these profiles arise in a decretion disk around the O9 companion , which is thus an O9e star .
The characteristics of the profiles are compatible with those of other Be/Oe stars .
The presence of this disk can explain the constant component of the continuum polarization of this system , for which the angle is perpendicular to the plane of the orbit , implying that the rotation axis of the O9e star is aligned with that of the orbit .
It remains to be explained why the disk is so stable within the strong ultraviolet radiation field of the O star .
We present a binary evolutionary scenario that is compatible with the current stellar and system parameters .