ICCD SPECKLE OBSERVATIONS OF BINARY STARS .9. A DUPLICITY SURVEY OF THE PLEIADES, PRAESEPE, AND IC-4665 CLUSTERS

Multiplicity of stars within clusters is a well-studied phenomenon. Ho wever, recent survey work done on the Hyades by Mason et al. [AJ, 105, 220 (1993)] would seem to indicate that even in the most often studie d clusters, there may be binaries yet undiscovered. In order to expand the sample of cluster binaries with potentially short-period visual o rbits, a speckle survey of 45 Pleiades, 54 Praesepe, and 22 IC 4665 br ight stars (V < 10) for possible multiplicity was conducted at the KPN O 4 m Mayall telescope between 1987 October and 1991 November. Of thes e, three new binaries have been discovered: one in the Pleiades where the new component may be spectroscopic, another in Praesepe which has been confirmed from examinations of archival observations and also has been resolved by occultation, and the third in IC 4665. Continued stu dy of these new binary stars could further refine the cluster distance moduli as well as the cluster mass-luminosity relations.