New Distance Measurements to the $α$ Persei and Pleiades Clusters

Abstract

We apply the new distance measuring technique of Hendry, O'Dell and Collier- Cameron, 1993, to the Pleiades and $α$ Persei clusters. The method relies on knowledge of the periods, rotation velocities and angular diameters of a sample of late-type stars within each cluster. The angular diameters were found by recalibrating the Barnes-Evans surface brightness relation. Applying our new distance method we derive a Pleiades distance in very good agreement with previous ZAMS fitting determinations, whereas our $α$ Persei distance appears substantially greater. In response to this greater distance, we apply a recent semi-empirical main-seqeunce fitting technique to $α$ Persei and confirm the findings of our new distance indicator. (Figures / preprint available on request)