Scientists unveil primitive stars within Milky Way’s centre

Researchers have made the most comprehensive set of in-depth observations of the oldest stars in the Milky Way’s centre as part of their study, demonstrating that the universe still has many undiscovered mysteries waiting to be discovered.

While the Pristine Inner Galaxy Survey (Pigs) team discovered that this cluster of stars is slowly rotating around the galactic centre, it was previously thought that this cluster of stars formed in a chaotic manner.

They also appear to spend most of their long lives close to the galaxy’s centre, according to research by Dr Anke Arentsen of the University of Cambridge, a member of the Pigs team, which was presented at the National Astronomy Meeting 2023 held at the University of Cardiff.

Some of the stars that were formed in the first billion years after the Big Bang and are still present today can be used to study the properties of galaxies as they first emerged.

They are easily recognised due to their pure chemical composition, which is primarily made up of hydrogen and helium and contains significantly fewer heavier elements than younger stars like the sun.

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Astronomers typically search for these old stars in the low-density halo surrounding our galaxy rather than in the Milky Way disc plane because it is easier to find them there.

The Milky Way’s innermost, densest regions are expected to house the galaxy’s oldest stars, according to models.

According to the researchers, it is challenging to find them in this region because of the thick interstellar dust that hides them and the rarity of old stars in comparison to the vast majority of their younger counterparts.

Dr Arentsen said: “It is exciting to think that we are seeing stars that formed in the earliest phases of the Milky Way, previously largely out of reach. These stars likely formed less than a billion years after the Big Bang, so are relics from the early universe.”

He added: “The available data for these ancient objects is growing rapidly. I’m excited to see what we will learn about these first stars to populate our galaxy in the next few years.”