AAO image reference AAT 76. « Previous || Next »
Top left is NE. Image width is about 24 arc min
Image and text © 1981-2010, Australian Astronomical Observatory, photograph by David Malin.
Among the many spectacular objects in the southern skies are two magnificent naked-eye globular clusters, omega Centauri and 47 Tucanae. Both these common names imply that they are stars, yet both are clearly non stellar, even to the casual naked-eye observer. In binoculars or a small telescope they resolve into vast numbers of tiny stars.
These clusters are ancient cities of stars and are captives of the Milky Way. They were formed long before our Galaxy assumed its present shape, indeed these clusters have some of the oldest known stars. 47 Tuc is about 15,000 light years distant and contains several million stars, as many as some minor galaxies. The crowded central region leads to occasional stellar encounters and it is in 47 Tuc that numerous, rapidly-spinning (milli-second) pulsars have been discovered by radio astronomers. Though the light of globular clusters is dominated by so-called 'red' giant stars, their colour is no redder than a domestic tungsten lamp, so the true colour of 47 Tuc is close to the pale pink-yellow reproduced here.
Related Images
AAT 76a. The globular cluster 47 Tucanae, NGC 104 (wide angle, portrait)
AAT 89. The globular cluster Omega Centauri, NGC 5139
AAT 89a. The globular cluster Omega Centauri, NGC 5139 (wide angle, portrait format)
AAT 89b. The globular cluster Omega Centauri, NGC 5139 (wide angle, landscape format)
Constellation of Tucana (external site)
For details of photographic exposure, search technical table by AAT reference number.