ω Centauri is the only globular star cluster in the Galactic halo known to have multiple stellar populations with a significant spread in iron abundance and age. But now Terzan 5, a globular-cluster-like system in the Galactic bulge, is reported to have two stellar populations with different iron contents and ages. So Terzan 5 could be the surviving remnant of one of the primordial building blocks which are thought to merge and form galaxy bulges.
- F. R. Ferraro
- E. Dalessandro
- G. Cocozza
