HST image of hot blue stars at the core of M15

A NASA/ ESA Hubble Space Telescope ( HST ) image of the center of globular cluster M15 reveals a new population of about 15 very hot stars isolated at the core.

The most likely explanation for their existence is that they are the 'naked cores' of stars that have been stripped of their outer envelope of gas. This could only have happened if stars were so crowded together in the cluster's core they can gravitationally pull material form each other.