The stars of a cluster are plotted on an H-R diagram. It is seen that the main sequence is well populated at the upper end and that there are many stars above (and to the right of) the main sequence at its lower end. What can be concluded about the age of this cluster?

Question

Quizplus · Accepted Answer

The presence of a well-populated upper main sequence and many stars above the main sequence at the lower end suggests that the cluster is very young. Massive stars, which populate the upper main sequence, have short lifespans and would not be present in an older cluster.

The Stars of a Cluster Are Plotted on an H-R