More than 100 observed galaxies are being disrupted and stripped of their outer layers, transforming them into fossil-dense, ultra-compact dwarf galaxies.

Astronomers have spotted the eroding remains of 100 dwarf galaxies that have been violently stripped of their outer layer of stars by larger galaxies. These disrupted galaxies represent the “missing link” in the evolution of a puzzling type of galaxy called ultra-compact dwarf galaxies (UCDs).

The discovery shows that UCDs  — which are  among the densest collections of stars in the universe —  are the fossilized remains of normal dwarf galaxies that have been destroyed in violent gravitational encounters with other galaxies.