We discovered an ancient cemetery of stars


As part of the Southern Stellar Stream Spectroscopic Survey Collaboration, a project to research and map the motion and chemistry of stellar currents in the Milky Way halo, researchers at the Carnegie Institution in the United States have discovered remains of globular clusters, in 2016. These remains are called stellar currents.

These stellar currents were found in the constellation of the Phoenix. According to the researchers, they come from a globular cluster, that is to say a very dense sphere made up of millions of stars, which was torn by the Milky Way about 2 billion years ago.

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The detection of this stellar current opens the way to new discoveries concerning globular clusters.

A stellar current that keeps traces of its formation

This stellar current is 150 light years in diameter and about 27,000 light years long. The discovery of these remnants of globular clusters is a boon for scientists, as they can derive a lot of information from them by studying its chemical composition.

“The remains of globular clusters that make up the Phoenix flow were disturbed several billion years ago, but fortunately retain the memory of its formation at the very beginning of the universe which is readable in the chemical composition of its stars” , explained Ting Li, an astronomer at the Carnegie Institution.

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A globular cluster that comes from a primitive universe

Analysis of the chemical composition of the stars in this stellar current has allowed scientists to determine that they were once part of a globular cluster that “Was formed in the early universe. “ The researchers came to this conclusion by studying the “metallicity”, that is, the metal content, of these stars.

You should know that globular clusters are enriched with heavy elements from previous generations of stars. However, the researchers found that the metallicity of stars in the star current of the constellation Phoenix is ​​lower than the minimum metallicity necessary for the formation of a globular cluster. This would mean that the cluster to which these stars belonged is of a completely different kind.

“One possible explanation is that this flow represents the last of its kind, the ultimate representative of a population of globular clusters born in environments radically different from those we see today”, Ting Li said.

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