Abstract
In the Galaxy, comprehensive empirical studies of advanced massive-star evolution via Wolf-Rayet (WR) stars have been hampered by huge disparities in apparent brightness and interstellar extinction, and by uncertainties in the distances. These problems all but disappear in the Magellanic Clouds (MCs), where one can also systematically probe the effects of lower initial metallicity (Z). Over two decades ago I began, partly involving Virpi Niemela, a vast optical spectroscopic program to examine all of the (then about 100) known MC WR stars for binarity and use them to extract information on general properties of WR stars. Now in 2006 the last step of this project is being wrapped up by the third doctoral student [Olivier Schnurr working on the WNL stars, after Peter Bartzakos (WC) in 1998 and Cédric Foellmi (WNE) in 2002] to embark on this project, now including the 144 known MC WR stars, as defined by the catalogues of Breysacher et al. for the LMC and Massey et al. for the SMC. Here we will summarize the highlights of this work. These include (1) a normal binary WR frequency in both MCs as in the Galaxy, (2) the increased presence of H in WNE stars, even binaries, as one goes to lower Z, (3) colliding winds, and (4) very massive WNLha stars. I will end with some suggestions for future work.
