Spectroscopic Searches for Evolutionary Orbital Period Changes in WR + OB Binaries: the Case of WR 141

Abstract

The results of new low-resolution spectroscopic observations of the short-period system WR 141 (WN5o + O5V–III, \(P \approx {{21.7}^{d}}\)), 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, are presented. A secular increase in the orbital period of WR 141 with a rate \(\dot {P} = 1.6 \pm 0.9\) s/yr, corresponding to a mass loss rate \({{\dot {M}}_{{{\text{WR}}}}} = (3.1 \pm 1.9) \times {{10}^{{ - 5}}} \;{{M}_{ \odot }}\)/yr with the masses of the stars in the system \({{M}_{{{\text{WR}}}}} = 39 \pm 10 \;{{M}_{ \odot }}\) and \({{M}_{{\text{O}}}} = 37 \pm 10\; {{M}_{ \odot }}\), is reported. A correlation between the mass loss rate of WR stars and their mass is discussed.