Radial velocity in a Wolf-Rayet/O-star couple

This orbit represents the first visual orbit for a WN star and only the third Wolf-Rayet star with a visual orbit. The orbit has a period of 112.8days, a moderate eccentricity of 0.36, and a separation of a=0.79 mas on the sky.

We combine the visual orbit with an SB2 orbit and Gaia parallax to find that the derived masses of the component stars are M_WR_=9.3{+/-}1.6M{odot} and M_O_=22.6{+/-}3.2M{odot}, with the large errors owing to the nearly face-on geometry of the system combined with errors in the spectroscopic parameters. We also derive an orbital parallax that is identical to the Gaia-determined distance. We present a preliminary spectral analysis and atmosphere models of the component stars, and find the mass-loss rate in agreement with polarization variability and our orbit.