ICCD speckle observations of binary stars. XXII. A survey of Wolf-Rayet stars for close visual companions

We present the results of a speckle interferometric survey for close visual companions, mainly among 29 of the apparently brightest Wolf-Rayet (W-R) s tars. Only one target, WR 48 = theta Mus, was resolved as a close astrometr ic binary (with a separation of 46 +/- 9 mas). This system is probably a tr iple comprising a short-period W-R binary plus a distant O supergiant compa nion. Although our binary detection fraction is low, it is not an unexpecte d result given the selection effects that militate against easy detection o f binaries. New, higher resolution observations will almost certainly incre ase the fraction of binaries. There are four known binaries among the six W -R stars in our sample that have nonthermal radio emission, and this connec tion supports the idea that the nonthermal emission originates in the wind- wind collision between components.