CCD photometric search for peculiar stars in open clusters

In a sample of six young open clusters (NGC 1502, NGC 3105, Stock 16, NGC 6268, NGC 7235, and NGC 7510) we investigated 1753 objects using the narrow band, three filter $\Delta a$ photometric system resulting in the detection of eleven bona-fide magnetic chemically peculiar (CP) stars and five Be or metal-weak stars. The results for the distant cluster NGC 3105 is most important because of the still unknown influence of the global metallicity gradient of the Milky Way. These findings confirm that CP stars are present in open clusters of very young ages (log t ≥ 6.90) at galactocentric distances up to 11.4 kpc. For all programme clusters the age, reddening, and distance modulus were derived using the corresponding isochrones. Some additional variable stars within Stock 16 could be identified by comparing different photometric studies.