THE LUMINOUS ECLIPSING SMC OB+WN BINARY HD 5980 BEFORE AND DURING THE RECENT LBV-LIKE OUTBURST: AN EXTREME CASE OF COLLIDING WINDS

摘要

The 1994 LBV-(luminous blue variable)like outburst of one of the luminous, hot components of the binary HD 5980 made it the brightest star in the Smal Magellanic Cloud for an interval of 5 months. The most intriguing question to arise from this event is the following: Why did the HD 5980 spectrum Change from an H-poor WN3 with veiled OB absorption lines about 20 yr ago to an H-rich WN11 Without central absorption lines during the outburst? In an attempt to answer this apparent enigma, we Present and analyze new phase-dependent spectroscopic, polarimetric, and light-curve observations.