A group of researchers have discovered a group of stars located at the center of Milky Way that they believe to be more than 13 billion years old. These stars are way older than the galaxy itself.
If you see the stars from Earth, it seemed like normal stars that flickers their lights on the night sky at the very middle of the galaxy. They do not look like any royalty, but these stars are the oldest stars ever been spotted by the human eye.
Astronomers from Australian National University (ANU) discovered the ancient stars. They believe that the stars were born at the time that the Universe is still young at 300 million years old.
According to lead author Louise Howes, “These pristine stars are among the oldest surviving stars in the Universe, and certainly the oldest stars we have ever seen.”
Howes further said that since the stars are older than the Milky Way, it is likely that the galaxy formed much later and around the stars without disturbing their positions.
“We’ve found what we think are the oldest stars in the galaxy and potentially the oldest objects ever discovered.”
Their team is very confident that these stars are actually as old as they believe considering some factors such as their location in the universe and composition as well.
Stars commonly contain hydrogen and helium, but other elements may exist in the composition of the star such as metals. In these old stars, they observed that it has very little “metal”. When stars explode in supernovae, their metal compositions are released into space that will later help form new stars.
If stars have very little metal composition, it is likely that they formed earlier in the history of Universe because there aren’t as many exploding stars sharing their scattered metals throughout space.
However, there are some metal-poor regions on the universe. And it is possible that these regions could give birth to new, young stars that are also metal-poor in composition.
So the researchers studied and analyzed the pattern in which stars are formed in the universe and found out that most, if not some, of them prefer to be born and live in the metal-rich and dense center of the Milky Way.
Considering that these stars are born in that exact location, the only reason that could explain a very low metal content is that they were formed much earlier than the Milky Way itself.
“The stars have surprisingly low levels of carbon, iron and other heavy element, which suggests the first stars might not have exploded as normal supernovae,” Howes said.
Their unusual discovery challenges existing theories with regards to what humans know about the environment of the ancient Universe.
It was not easy to calculate the approximate age of the stars being in subject.
In their study, they used ANU’s SkyMapper Telescope to observe 5 million stars existing in the center of the galaxy. And then they choose 14,000 stars from the initial group to be examined and analyzed individually. And further eliminated to what now remains 23 stars that hold the spotlight in the team’s paper.
“The Milky Way is so massive and we’re only such a small part of it,” said Howes.
“What I hope to be able to do in the future is to work out exactly how the Milky Way formed and these stars are the very first building blocks of that.”
The study was published in the journal Nature.