With the use of NASA’s Hubble Space Telescope, astronomers were able to observe globular clusters-- compactly packed collection of stars that normally contain older stars. In the case of 47 Tucanae, roughly 16,700 light years from earth, the cluster is 10.5 billion years old.
Harvey Richer, lead author of the study and professor at the University of British Columbia, and his colleagues evaluated 754 archived photos of 47 Tucanae captured by Hubble. They mapped out the changes in the arrangement of the stars throughout the years. They were able to distinguish the stars in the cluster into two groups based on their age. The red stars, which means older, travelled in random circular orbits while the blue stars, which means younger, travelled in an elliptical pattern. The movement makes them look like they are dancing which astronomers refer to as cosmic choreography or cosmic dance.
Astronomers said the younger stars were created from the older stars and are more or less 100 million years younger.
The astronomers believe that the older stars are in process of cooling down and are releasing gas into the globular cluster. The gas carried heavier elements that soon crashed with the surrounding environment, generating a “chemically enriched generation of stars.”
Earlier research was able to identify a star’s age based on its chemical composition. With these observations within a globular cluster, astronomers now have evidence of stars being born at different times within one cluster. Richer’s work now includes star movement as a gauge of age within a cluster, and he acclaims Hubble’s capability to provide thorough data of 47 Tucanae for the breakthrough.
“These data are so good; we can actually see the individual motions of the stars within the cluster. The data offer detailed evidence to help us understand how various stellar populations formed in such clusters,” Richer wrote in the report.
Hubble’s data also was used to discover three generations of stars in the globular cluster in the constellation Carina, NGC 2808, one of our home galaxy's most gigantic clusters, containing more than a million stars and is projected to be 12.5-billion years old.
The study was published in the Astrophysical Journal Letters.
