47 Tacanae

47 Tuc, or 47 Tacanae, is a Globular Cluster which you will find as todays target in Universe Watch.


47 Tucanae

47 Tucanae ( Click to Enlarge)

As you can see with the picture on the left, 47 Tuc resembles a big ball of stars in space and it is impossible to make out the individual stars in the middle.With a magnitude of 4.0 it is visible to the naked eye.


Due to it’s close proximity to the celestial pole, 47 tuc will never set and can always be found above the horizon. So during the day this globular cluster will complete a small circle around the celestial pole while other objects in the sky further from the celestial pole will rotate in larger circles and hence dip below the horizon during portions of their circular path.

Back in 2000, scientists were targeting 47 Tucanae with the hubble telescope in an effort to locate Jupiter-like gas giants within the globular cluster. This involved checking the stars as you see in the picture for any sign of a planet transiting any one of the stars. This means that when a planet moves between us and the star, the star should dim in magnitude and be picked up by hubble.

However the scientists came up empty handed and found no evidence of these planets. This led to the belief that where globular clusters are concerned, planets are rare or completely non-existant  in globular clusters due to the low concentration of heavy elements in the globular cluster. Heavy elements, which to astronomers is any element heavier than helium, is essential for forming planetary systems as well as the evolution of life.

But then in 2003, an ancient planet was found to exist in the globular cluster M4 which is currently not visible from Sydney at night. This planet, which is two or three times larger than Jupiter, is the only planet so far found to be orbiting around two stars…. in this case around both a white dwarf half the size of our sun as well as around a rapidly spinning neutron star. The finding of this planet leads to the theory that perhaps in certain conditions planets can form in globular clusters after all.

The planet in M4 most likely formed along with the other stars in the cluster in the first billion years that the universe itself existed…… and formed at the same time that our mily way galaxy began forming. so this is truly one ancient planet that was found in 2003.

Check out more on 47 Tuc which is todays topic in Universe Watch.

~ by sydneystargazers on October 21, 2009.

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