Studies of Young Stellar Objects

Abstract

We present a detailed study of four young open star clusters and two OB associations using deep CCD U B V R I and 2MASS J H Ks measurements. Physical parameters of the clusters have been estimated using optical as well as near-IR data. Ages of objects under study range 10-100 Myr. Mass function slope of the sample of clusters are in agreement with the Salpeter (1955) value. From a comparison of mass function slope of clusters and OB associations in our Galaxy with those in external galaxies, we urgue that the star formation processes are such that they yield almost similar stellar mass distribution in vastly different star forming environments. Mass segregation suggests that the clusters under study are dynamically relaxed and hence mass segregation may be due to dynamical evolution or imprint of star formation or both. The extinction properties of a sample of 18 young star clusters have been investigated utilizing recent data available in literature. The study suggests that there is no uniformity in extinction properties amongst these clusters. A non-uniform extinction has been noticed for the first time in NGC 1502 and Tr 37 along with the existence of circumstellar shell around some early type stars in NGC 884, NGC 2264, Tr 14 and Tr 16.