A “galactical galactic fossil” in the Milky Way that is about 12 billion years old is finally spilling its secrets. A recent study published by world-renowned astronomers revealed that thanks to the Hubble Space Telescope and other sophisticated gadgets they were able to get a better analysis of Terzan 5, which is 19 000 light-years from Earth.
French astronomer Agop Terzan discovered Terzan 5 in 1968, and there was not much known about it other than the fact it is a heavily obscured globular cluster belonging to the bulge of the Milky Way galaxy.
Now 40 years later, thanks to a study led by Davide Massari, from INAF in Italy and the University of Groningen in the Netherlands, and Francesco Ferraro, professor in the physics and astronomy department at the University of Bologna in Italy, the world is learning more about the galactic fossil.
The scientists have discovered that there are “two distinct kinds of stars in Terzan 5,” which not only contain different elements, but have an age gap of roughly 7 billion years. The gap means that the star formation process in Terzan 5 was not continuous, but occurred during two distinct bursts. One took place 12 billion years ago and the other 4.5 billion years ago. Massari stated:
“This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive. At least 100 million times the mass of the Sun.”
Ferraro said that his research also led to the surprising discovery that Terzan 5 fluctuated in size. Ferraro explained:
“After the first burst of star formation, there was a supernovae explosion. However, at the time, Terzan 5 was so massive that rather than ejecting the iron-enriched gas created by the explosion, it retained that gas to form a new generation of stars 7 billion years later.”
He later explained that Terzan 5 was about 100 million times the mass of the sun to produce both bursts of star formation. However, now it is just a few million times the mass of the sun. Ferraro claimed:
“Current models of galaxy bulge formation assume that vast clumps of gas and stars interacted to form the primordial bulges of galaxies, merging and dissolving in the process. The progenitor of Terzan 5 might have been one of these clumps which survived complete destruction.”
The experts argued that studying this building block of the galaxy can provide a better understanding of galaxy formation and the Milky Way. Ferraro and his team “…will continue looking for other stellar systems that might also be hiding in the Milky Way to see what other secrets these ancient building blocks at the center of our galaxy might contain.”
