Composite colour-magnitude and colour-colour diagrams for Be stars in open clusters

By the end of 1980, the total number of Be stars discovered in the field of open clusters amounted to 180 stars distributed in 60 clusters. Among these, 110 Be stars belong to 32 clusters included in the sample studied, which contains 75 open clusters younger than the Hyades. But only 88 stars with complete UBV photoelectric photometry have been taken into consideration here. The concept of age groups, defined elsewhere (Mermilliod 1981a), is used throughout the present analysis, as well as the new estimate of the colour excesses and distance moduli obtained for these 32 clusters. Under the assumption of uniform reddening across the clusters, absolute magnitudes and dereddened colour indices have been calculated for the 88 Be stars. (Auth.)