Spectroscopic searches for evolutionary orbital period changes in WR+OB binaries: the case of WR 141

The results of new low-resolution spectroscopic observations of the short-period system WR 141 (WN5o+O5V–III, P ≈ 21.7^d) are presented, as well as the results of their comparison with the material of previous studies in order to search for an evolutionary change in the orbital period. A secular increase in the orbital period of WR 141 with a rate of $\dot{Р}=1.6\pm 0.9$ sec/year, corresponding to a mass loss rate of ${\dot{M}}_{WR}=(3.1\pm 1.9)\times {10}^{-5}{М}_{\odot }/\mathrm{yr}$ with the masses of the stars in the system of $M_{\mathrm{WR}}=39\pm 10M_{\mathrm{ʘ}}$ and $M_{\mathrm{O}}=37\pm 10M_{\mathrm{ʘ}}$, is reported. A correlation between the mass loss rate of WR stars and their mass is discussed.