We present the results of optical wavelength observations of the unusual SMC eclipsing binary system HD 5980 obtained in 1999 and 2004–2005 .
Radial velocity curves for the erupting LBV/WR object ( star A ) and its close WR-like companion ( star B ) are obtained by deblending the variable emission-line profiles of NIV and NV lines .
The derived masses M _ { A } = 58–79 M _ { \odot } and M _ { B } = 51–67 M _ { \odot } , are more consistent with the the stars ’ location near the top of the HRD than previous estimates .
The presence of a wind-wind interaction region is inferred from the orbital phase-dependent behavior of He I P Cygni absorption components .
The emission-line intensities continued with the declining trend previously seen in UV spectra .
The behavior of the photospheric absorption lines is consistent with the results of Schweickhardt ( 2002 ) who concludes that the third object in the combined spectrum , star C , is also a binary system with P _ { starC } \sim 96.5 days , e = 0.83 .