The concentrated light of one million stars packed into a volume
of space 120 light years across makes 47 Tucanae the second brightest
globular cluster in the sky, surpassed only by Omega Centauri.
If earth were placed near the center of 47 Tucanae the collective
starlight would create a nighttime as bright as day. Although
it is the classic metal rich cluster, its metal abundance is still
only 25% that of our sun. Metal abundance appears to have implications
regarding a stars suitability to form planets. A concerted effort
was made by the Hubble Space Telescope to search for planets within
47 Tucanae but failed to find any. The lack of planets in this
compact star system supports the belief that metal poor stars
in general are not conducive to planet formation. Recent work
though has astronomers reconsidering this conclusion as there
may still be a strong possibility of gas-giant planets located
much further out from stars in globular clusters.
The crowded core of 47 Tucanae is a virtual laboratory of exotic
objects such as millisecond pulsars (neutron stars rotating from
100 to 1000 times per second), compact binary systems and possibly
even stellar mass black holes. 47 Tucanae has the highest number
of known radio pulsars of any cluster. Strong evidence exists
for stellar collisions within the tight confines of the compact
core. A subset of enigmatic blue stars known as "Blue Stragglers",
first described by Alan Sandage in 1953, have been identified
in the overcrowded cluster core of 47 Tucanae. These mysterious
stars received their name because they appear to be "straggling"
away from the evolutionary path of normal stars. They are twice
as massive and one fifth the age as typical stars in the cluster.
Their age, mass and location in the densest regions of the cluster
center suggests that they formed from collisions and mergers of
lower mass stars.