Observations of pre-main-sequence stars in the Pleiades

Location of the Pleiades pre-main sequence turn-on is discussed along with new photometric and spectroscopic observations of faint stars in the cluster. BVRI photometry results show a pre-main sequence turn-on at approximately M(v) = +9.4m and a contraction age for the Cluster is inferred at 2.2 x 10 to the 8th yr. The discrepancy between the nuclear age for the Pleiades derived from high mass stars and the contraction age derived from low mass stars could be quantified with the results if the models are correct. The observing list for the Pleiades program was selected mostly from a set of relatively bright stars (12.5 m less than 14.5 m) observed in the near-infrared by Zappala (1971) and a set of generally fainter stars with proper motions indicative of Pleiades membership (Jones 1977). Comparisons are made between the Pleiades data and photometric data from Hyades.