Radial distribution of the integrated light and photometric colours in open star clusters

Abstract

Mass segregation in the form of preferential concentration of more massive stars in the central regions of a number of open star clusters has been known for some time. In this paper, integrated UBV colours in concentric zones have been estimated for 12 nearby open clusters using the observations of individual cluster members. It is found that the clusters showing pronounced mass segregation also show significant radial variations in the integrated colours. However, the effects of stochastic fluctuations around the massive portion of the mass distribution function on the integrated colours should be taken into consideration, if they are present.