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Why are the stars in globular clusters made of material different to other stars found in the Milky Way Galaxy? Perplexing, isn't it. But do not worry. A team of international astronomers have proposed a new theory that attempts to explain the existence of peculiar chemical elements in ancient clusters called 'globular clusters'.
Globular clusters are ancient compact clusters of hundreds of thousands of stars clumped tightly together via gravity which were formed 11-13 billion years ago, just a few cosmic moments after the Big Bang.
Around 150 of these clusters have been spotted sitting at the outer regions of the Milky Way, Tech Times reported on Friday.
The researchers wanted to know why the stars found in these clusters have different chemical elements than others found in open clusters.
Aside from the significantly higher amounts of helium and hydrogen, stars in globular clusters also have heavier concentration of heavy elements than other stars such as the Sun.
This is often seen in older stars such as those found in globular clusters, but scientists have yet to know what caused this particular ratio of elements.
The elements and their particular ratio could not have been produced within the stars themselves. The researchers believe it requires a temperature 10 times hotter than that of the stars while they were forming.
A team of astronomers believe that it could be seen in supermassive stars, having a mass that is tens of thousands of times more than the mass of the Sun.
The study, published in the journal Monthly Notices of the Royal Astronomical Society, advances the idea that supermassive stars may have come around at the same time as the globular clusters were starting to form.
During the early years of the Universe, globular clusters were filled with dense hot gas that would later cool to form the cluster's huge number of stars.
As the stars accumulated more material, the researchers believe they became so big and so close to one another that some of them would collide to form a supermassive star.
The supermassive star would then reach temperatures high enough to be able to produce heavy elements and other chemicals that can now be observed in stars in globular clusters.
"What is truly novel in our model is that the formation of the supermassive stars and the globular clusters are intimately linked," said lead investigator Mark Gieles, from the University of Surrey.
"And this new mechanism is the first model that can form enough material to pollute the cluster, and with the correct abundance of different elements," Gieles added.
