MEMBERSHIPS AND CM DIAGRAMS OF YOUNG OPEN CLUSTERS .1. NGC-225

An astrometric, photometric, and spectroscopic investigation of the loose open cluster NGC 225 is presented. The proper motions of 289 stars (cluster + field) have been measured, with errors ranging from 0.10 to 0.25"/century, on PDS scans of astrometric plates spanning a time interval of up to 88 yr. A total of 28 members down to B = 16.1m have been identified. V magnitude and (B - V) color index have been determined for all 289 stars with means errors of about 0.04m and 0.07m, respectively, while spectral classifications have been obtained for 62 stars. The cluster NGC 225 is of low mass (60M. less-than-or-equal-to M(TOT) less-than-or-equal-to 88 M.), young (t = 1.2 x 10(8) yr), nearby (r = 525 +/- 73 pc), moderately obscured (<E(B-V)> = 0.25 +/- 0.08), and with a marked differential reddening. The more massive stars are concentrated towards the cluster core; they seem to move more slowly than the less massive stars, which would indicate relaxation and energy equipartition. Also, a possible runaway has been identified and a real deficiency of less massive stars seems to be present.