The stars below the horizontal-branch in the globular cluster M 92

The four-color CM-Diagram of M 92 shows a group of stars that fall about 0.5 mag below the horizontal branch. The majority of these stars are located in or near the core of the cluster. Extensive tests have been made to confirm the reality of the stellar magnitudes and colors of these stars and to confirm that they are cluster members: The conclusion of these studies is that this group of stars is made up of cluster members and that they are intrinsically less luminous than the other blue stars in the cluster.