E. J. Aldoretta, N. St-Louis, N. D. Richardson, Anthony F. J. Moffat, T. Eversberg, G. M. Hill, Tomer Shenar, E. Artigau, B. Gauza, J. H. Knapen, Jiří Kubat, Brankica Kubatova, R. Maltais-Tariant, M. Munoz, H. Pablo, T. Ramiaramanantsoa, A. Richard-Laferriere, D. P. Sablowski, S. Simon-Diaz, L. St-Jean, F. Bolduan, F. M. Dias, P. Dubreuil, D. Fuchs, T. Garrel, G. Grutzeck, T. Hunger, D. Kuesters, M. Langenbrink, R. Leadbeater, D. Li, A. Lopez, B. Mauclaire, T. Moldenhawer, M. Potter, E. M. dos Santos, L. Schanne, J. Schmidt, H. Sieske, J. Strachan, E. Stinner, P. Stinner, B. Stober, K. Strandbaek, T. Syder, D. Verilhac, U. Waldschlaeger, D. Weiss, A. Wendt

• During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He ii lambda 5411 emission line, the previously identified period was refined to P = 2.255 +/- 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 +/- 6 d, or similar to 18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Delta I center dot a parts per thousand integral 90A degrees was determined between theDuring the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He ii lambda 5411 emission line, the previously identified period was refined to P = 2.255 +/- 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 +/- 6 d, or similar to 18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Delta I center dot a parts per thousand integral 90A degrees was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C iv lambda lambda 5802,5812 and He i lambda 5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He i lambda 5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist.…