Astronomers find 'the oldest stars we have ever seen'

These two newly discovered stars were born 13.6 billion years ago, say astronomers – just 200 million years after the Big Bang.

M.Kornmesser and R. Hurt/Caltech/JPL/NASA/ESO
An artist's impression of the Milky Way galaxy, highlighting the central bulge, where two of the universe's oldest stars were recently found.

Two newly discovered stars may provide clues to the birth of the universe.

Scientists estimate that these stars, named SMSS J181609.62 -333218.7 and SMSS J031300.36 -670839.3, were born 13.6 billion years ago – about 200 million years after the Big Bang.

"These pristine stars are among the oldest surviving stars in the universe, and certainly the oldest stars we have ever seen," said Louise Howes, lead author of the study, in a press release.

Astronomers discovered the stars using the SkyMapper telescope located at Australian National University (ANU), which they are using to create a census of the galaxy’s stars, among other projects.

These ancient stars give clues to the early composition of our galaxy, report Dr. Howes and her colleagues in the latest issue of Nature. One of their most significant findings was that early stars such as these probably formed through hypernovas – explosions even more powerful than supernovas.

"A hypernova is a special kind of supernova which produces about ten times as much energy as a regular supernova," Howes told ABC Australia.

When the very earliest stars died in hypernovas, they sent rich particles of dust and gas hurtling towards the Milky Way’s center bulge, where these two stars are located.

Scientists have long known that the galactic center is likely to hold the Milky Way's oldest stars, due to their composition. Each new generation of stars is richer in metals than the last, but the stars located in the Milky Way’s central bulge are extremely metal-poor.

"These stars formed before the Milky Way, and the galaxy formed around them," said Howes, who performed much of the research while a PhD student at the ANU Research School of Astronomy and Astrophysics.

Although the astronomers knew what to look for, finding these ancient stars was not easy. Project leader Professor Martin Asplund compared looking for the oldest stars – among the many billions of stars that make up this galaxy – to the hunt for a needle in a haystack.

"The ANU SkyMapper telescope has a unique ability to detect the distinct colors of anemic stars – stars with little iron – which has been vital for this search," he said.

But for the astronomers, the value of their discovery more than compensated for the difficulty of the search.

"This work really changes our ideas of what the first stars would have looked like, and how they would have developed and died, and how the galaxy would have evolved, and also sheds light on the formation of all the elements in the universe," Howes told Space.com.

Going forward, she and her colleagues plan to examine other metal-poor stars in the Milky Way’s central bulge to learn more about the early galaxy.     

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to Astronomers find 'the oldest stars we have ever seen'
Read this article in
https://www.csmonitor.com/Science/2015/1112/Astronomers-find-the-oldest-stars-we-have-ever-seen
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe