Hubble Space Telescope observations of the luminous blue variable/W-R eclipsing binary system HD 5980

We report the results of Hubble Space Telescope STIS observations of the in triguing luminous blue variable/Wolf-Rayet binary system HD 5980 in the Sma ll Magellanic Cloud. Although its spectral characteristics (WN6) are curren tly very similar to those observed in 1995 in the FUV, some of the line flu xes continue with the increasing trend observed since the 1980s. The erupti ng star still dominates the emission-line spectrum, and a radial velocity c urve from UV lines is derived, supporting previous estimates of its mass (5 0 M.). A rough estimate of 2 x 10(-4) M. yr(-1) for the current mass-loss r ate of this star is derived. The only spectral lines attributable to the cl ose companion are the very extended P Cygni absorption components of the st rong UV lines, present only during the eclipse of the eruptor, implying tha t the wind-wind collision shock cone winds tightly around this companion. A third stellar component contributing to the spectrum is detected through t he presence of stationary photospheric absorption lines in the UV spectrum. This object contributes similar to 30% to the UV continuum luminosity. A n ew set of ISM absorption components at -680 km s(-1) has appeared as a resu lt of the shock interface between the slow wind (similar to 400 km s(-1)) t hat emerged during the 1994 eruption and the subsequently emerging fast win d (similar to 2000 km s(-1)) phases.