ANCIENT CLUSTER OF STARS FOUND RIPPED APART BY OUR MILKY WAY

An ancient cluster of stars that was ripped apart more than two billion years ago, by our own Milky Way, was recently found by scientists.

Scientists explained that a cluster is formed out of a million stars that are stuck together by gravity, and that our Milky Way contains over 150 of them.

The recent discovery of the destroyed cluster offers a way of looking back to the universe’s younger years, and has changed scientist's understanding of how such objects form in the galaxy.

With the recent findings, scientists have discovered that the cluster’s time was different from those others formed today.

One of the astronomers from the Carnegie Institution for Science who made the discovery, Alexander Ji, stated that; "This is stellar archeology, uncovering the remnants of something ancient, swept along in a more-recent phenomenon."

Scientists believe that although the cluster was torn apart, it is still the last of its kind and still holds a memory of a kind of celestial structure.

Astronomer Ting Li added that, "The globular cluster remnants that make up the Phoenix Stream were disrupted many billions of years ago, but luckily retain the memory of its formation in the very early universe, which we can read from the chemical composition of its stars."

A PhD student at the University of Sydney, Zhen Wan, who also led the new study, explained that once scientists discovered which stars belonged to the stream, they were able to measure the abundance of elements heavier that hydrogen and helium, which is also referred to as metallicity.  

"We were really surprised to find that the Phoenix Stream has a very low metallicity, making it distinctly different to all of the other globular clusters in the Galaxy. Even though the cluster was destroyed billions of years ago, we can still tell it formed in the early Universe from the composition of its stars", commented Wan.

Astronomers were stunned by finding that the metallicity of the cluster recently found was lower that pervious discoveries, where globular cluster stars are enriched with heavier elements, and would not have expected the cluster to have the ability to form.

Co-author Associate Professor, Daniel Zucker, from Macquarie University also commented on the strange discover and stated that; "This stream comes from a cluster that, by our understanding, shouldn't have existed."

Researchers now hope to discover whether there are more examples of this stream.

"The next question to ask is whether there are more ancient remnants out there, the leftovers of a population that no longer exists. Finding more such streams will give us a new view of what was going on in the early Universe," Dr Li concluded.