Interstellar extinction in the open clusters towards galactic longitude around 130◦

Abstract

In this paper we present a detailed study of the intra-cluster reddening material in the young open clusters located around l ∼ 130◦ using colour-excess diagrams and two-colour diagrams. The study supports the universality of the extinction curves for λ ≥ λȷ ,Whereas for shorter wavelengths the curve depends upon the value of the R cluster (total-to-selective absorption

in the cluster region). The value of R cluster in the case of NGC 654, NGC 869 and NGC 884 is found to be normal, whereas the

value of R cluster in the cluster regions NGC 1502 and IC 1805 indicates an anomalous reddening law in these regions. In the case

of NGC 1502 the value of R cluster is found to be lower (2.57 ± 0.27) whereas in the case of IC 1805 it is higher (3.56 ± 0.29)

than the normal value of 3.1. Although the intra-cluster material indicates a higher value of R cluster in the NGC 663 region, the

error in the estimation of R cluster is too large to conclude anything. It is also found that the extinction process in the U band in

the case of NGC 663 seems to be less efficient, whereas in the case of NGC 869 the process is more efficient.