The Color-Magnitude Diagram of the Pleiades Cluster. II.

Two- or three-color photographic and photoelectric photometry of virtually all the known members of the Pleiades cluster is given. The photographic photometry was done on plates taken with the 13-inch telescope, while the photoelectric work was done with the 21- and 42-inch reflectors of the Lowell Observatory. We believe that a number of the stars that were previously thought to be members of the Pleiades are actually not members. We find a total of 262 members and 27 probable members brighter than V = 16. No white dwarfs were found. They would have been found if they had been brighter than = 11.8. A sudden increase in the width of the main sequence is observed at V = 12.0. This scatter may be associated with the probable fact that the fainter stars are still in the process of gravitational contraction. A "flare" of one faint Pleiades star was observed, and 5 other faint stars are thought also to be "flare" stars. It is suggested that the "flare" activity might be connected with the process of gravitational contraction of young late-type stars.