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 ≈ 21.7d) 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 ofР˙=1.6±0.9 sec/year, corresponding to a mass loss rate of M˙WR=(3.1±1.9)×10-5М⊙/yr with the masses of the stars in the system of MWR=39±10Mʘ and MO=37±10Mʘ, is reported. A correlation between the mass loss rate of WR stars and their mass is discussed.