Revista Mexicana de Astronomía y Astrofísica ISSN: 0185-1101 [email protected] Instituto de Astronomía México

Koenigsberger, G. On the Nature of the LBV/WR Eclipsing Binary System HD 5980 Revista Mexicana de Astronomía y Astrofísica, vol. 40, núm. 2, octubre, 2004, pp. 107-135 Instituto de Astronomía Distrito Federal, México

Available in: http://www.redalyc.org/articulo.oa?id=57140201

Abstract HD 5980 is a multiple star system in the Small Magellanic Cloud that underwent a luminous blue variable-like eruption in 1993- 1994. The erupting star (star A) forms part of a close eclipsing binary whose companion`s (star B) Wolf- Rayet nature has recently been questioned. The data analyzed in this paper cover the period 1979-2002, and support the WNE classification of star B. The orbital phase-dependent variations of ultraviolet P Cygni absorption lines imply that the wind speed of star A is 1700{2200 km s1 and that of star B is 2600{3100 km s1. These allow an estimate of the wind-wind collision (wwc) shock cone geometry and line profiles from the wwc region. Given the assumed mass-loss rates, only a small fraction of the observed emission line profies may originate in the wwc region. The star A+star B binary pair is likely the result of evolution with mass transfer and/or evolution with rapid rotation, and provides a magnificent opportunity for studying the processes that occur in massive multiple systems at the stages of stellar evolution just prior to the supernova event.

Keywords STARS: BINARIES (ECLIPSING), STARS: INDIVIDUAL (HD 5980), STARS: WINDS, OUTFLOWS, STARS: WOLF-RAYET, STARS: VARIABLES (LUMINOUS BLUE VARIABLES)

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