A LONG-PERIOD SPECTROSCOPIC BINARY IN THE O-STAR MULTIPLE SYSTEM HD193322

We present radial velocity measurements and a single-lined spectroscop ic orbit for the bright O-type star, HD 193322A, which we shaw to be a 311 day binary system that has a distant third companion (detected by speckle interferometry) in a 31 yr orbit. We suggest that the speckle companion appears in the spectrum as a broad-lined component of early B type. We also present a spectrum of the visual companion, HD 193322 B, which appears to be an unresolved, double-lined spectroscopic binar y. Thus, HD 193322, the central object in the open cluster Collinder 4 19, is a multiple system that contains at least five stars (possibly s even if the C and D components are physical). Such systems may play a key role in the dynamical ejection of runaway stars from young cluster s.