Program: GS-2023A-Q-415

Massive binary systems for which the orbital parameters can be determined are precious objects. The masses of the stellar components can be obtained by simple, least model-dependent Keplerian orbit, and compared with the evolution models and their scenarios. A blind spectral monitoring revealed that the Wolf-Rayet star WR 36 is in fact a binary system. Originally classified as WN5-s, where the "s" stands for strong lines, we can now say that there are actually two WR stars contributing to the spectrum! Moreover, preliminary results indicate that the system has a low inclinaition with respect to the line of sight, giving hope that eclipses can be seen in the system's light curve. The inclination can be determined within 10 deg by the measurement of eclipses and from the analysis of the emission from the collision zone of the winds of the two stars. There are only 6 other comparable systems known in our Galaxy, none of wich are composed of two He-core WR stars like WR 36. We propose 10 observations in photometry and spectroscopy in order to determine the system orbital period, radial velocity amplitude and inclination.