Omega Centauri

Omega Centauri is the largest and most massive globular cluster in the Milky Way — a gravitationally bound sphere containing approximately 10 million stars, packed into a region about 150 light-years across. It is the only globular cluster visible to the naked eye from mid-southern latitudes, appearing as a fuzzy star.

Unlike most globular clusters, which contain stars of a single age and chemical composition, Omega Centauri shows a complex population of stars with multiple distinct age groups spanning several billion years. This has led to the hypothesis that it may be the stripped nucleus of a dwarf galaxy that was absorbed by the Milky Way long ago.

Hubble’s high-resolution imaging resolves the individual stars in the cluster’s crowded core, where densities reach millions of stars per cubic light-year — thousands of times greater than the solar neighborhood. Stars here are close enough that multi-star gravitational interactions are frequent.

There is strong observational evidence for an intermediate-mass black hole at the center of Omega Centauri, with a mass possibly reaching tens of thousands of solar masses.