REDDENING, DISTANCE MODULUS, CHEMICAL COMPOSITION AND AGE OF GALACTIC CLUSTER NGC 752

The uvbyp colours of the stars in the galactic cluster NGC 752 have been analysed using theoretical colours computed from synthetic stellar spectra. The cluster reddening has been found to be small with E(b-y) = 0*004 magnitudes. The distance modulus is found to be 7*8 magnitudes and the mi indices imply that the cluster may be slightly metal rich ([M/H] = +0-2) compared with the Sun. Equivalent width data for one cluster star, originally obtained by Gunn & Kraft, have been re-analysed and have also been found to give slight metal richness. The cluster age is found to be about 2-5 x io9 yr, based on Iben's evolutionary tracks for stars of 1*25 and 1*5 Jt 0. Not all details of the theoretical isochrones agree with observation and further investigation of evolutionary tracks for stars in this mass range appears warranted. The desirability of obtaining uvbyp photometry for the old galactic cluster M67 is pointed out. © Royal Astronomical Society.