A radial-velocity survey of the Hyades

A comprehensive survey of the radial velocities of stars suggested as Hyades members has been carried out photoelectrically with the 200 in. Hale Telescope. More than 400 stars, mostly identified in proper-motion studies, have been observed; for instrumental reasons they are largely restricted to the magnitude range 6 &lt; V &lt; 14. About half of them have proved to be members of the cluster. Relative velocities having external errors as small as 0.1 km s<SUP>-1</SUP> have been established for a considerable number of them. It is possible to assign nearly every binary, as well as virtually all the other objects for which repeated observations have disclosed no variation, to either the member or nonmember category. More than 60 of the stars identified as cluster members are spectroscopic binaries, few of which were recognized as such before this study. The authors present a Hyades color-magnitude diagram which is thought to be almost completely purged of nonmember interlopers and in which the upward bias caused by unrecognized duplicity of the member stars must be much reduced in comparison with previous diagrams.

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