SIMBAD references

We present the results of the analysis of 151 spectra of the Wolf-Rayet star HD 4004 (WR1) obtained in 1999 and in 2005. The line-profile variability is found to be periodic, with P=7.684 days, and to have characteristics that are very similar to those of another variable WR star, HD 50896 (WR6). The similarities point toward a common physical phenomenon in both systems. Of the scenarios that can explain the observations, such as colliding winds in two stars with similar wind momenta and the ejection of streams or jets from two opposite locations on the stellar surface, the latter seems more likely due to the lack of observational evidence for a strong wind-bearing companion.