The age distribution of open clusters as a function of Trumpler's classification

Abstract

The age distribution of open clusters is studied as a function of Trumpler's central concentration and range in brightness classes. For different Trumpler's classes within 1 kpc, it is shown that the observed distribution of open clusters is not seriously affected by selection effects. The lifetimes of the clusters are obtained for each class. It is found that rich clusters have a relatively higher central concentration than medium and poor clusters