NEW DISTANCE MEASUREMENTS TO THE PLEIADES AND ALPHA-PERSEI CLUSTERS

We apply the new distance measuring technique of Hendry, O'Dell & Collier Cameron to the Pleiades and alpha Persei clusters. The method relies on knowledge of the periods, rotational velocities and angular diameters of a small sample of the late-type stars within each cluster. The angular diameters of these stars were found by recalibrating the Barnes-Evans surface brightness relation for an improved calibration sample in the spectral range -0.15 less-than-or-equal-to (B - V)0 less-than-or-equal-to 1.3 5. Applying our new distance method, we derive a true distance modulus (m - M)0 = 5.60 mag for the Pleiades, and (m - M)0 = 6.35 mag for alpha Persei. Our determination of the Pleiades distance is in good agreement with previous zero-age main-sequence fitting techniques, whereas our distance for alpha Persei appears substantially greater. In response to the greater distance for alpha Persei, we apply the relatively recent semi-empirical main-sequence fitting method of Vandenberg & Poll, which yields a true distance modulus of (m - M)0 = 6.25 mag, thereby providing substantial support for our findings.