47 Tucanae [SEP] time of discovery
Africa.
47 Tucanae is the second brightest globular cluster after Omega Centauri, and telescopically reveals about ten thousand stars, many appearing within a small dense central core. The cluster may contain an intermediate-mass black hole.
Early history.
The cluster was given its Bayer designation ξ Tucanae in Johann Bayer's "Uranometria" (1603). It was recorded as a cluster in 1751-2 by Nicolas-Louis de Lacaille, who initially thought it was the nucleus of a bright comet. Lacaille then listed
a redshift z = 1.345, separated by 4.2 arcsec in projection, corresponding to a physical separation distance of 25 kpc.
- Discovery of a new gravitational lens candidate, associated with the quasar UM 425 = QSO 1120+019.
- Discovery of two high-velocity stars shot out of the core of the globular cluster 47 Tucanae.
- First dynamical mapping in the core of a collapsed globular cluster, namely, M15.
- Spectroscopic identification providing the long awaited redshift measurement of the heavily obscured, gravitationally