Scientists Discover Universe's Oldest Star

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The star is 4 billion years older than any other found to date. NPR's Rachel Martin talks to Timothy Beers of the National Optical Astronomy Observatory in Arizona.



Scientists have discovered the oldest star in the galaxy. And it's really old, 13.6 billion years. Now to be clear, they had known about this star before but hadn't yet figured out its age. This star is four billion years older than any other star found to date.

Here to more to talk about what this star can tell us about the great beyond is Timothy Beers, of the National Optical Astronomy Observatory in Tucson, Arizona. Thanks so much for being with us.

TIMOTHY BEERS: Oh, it's a pleasure to be here, Rachel.

MARTIN: So was it surprising to the science community to discover this star?

BEERS: Well, I and my colleagues have been looking for these extreme low metallicity stars for almost three decades now. They've been known to exist, at least suspected to exist for quite some time, but they are so incredibly rare, that you have to sift through so many stars, in order to find these rare examples that tell us the most about the early chemistry of the universe. So it's very satisfying to reach down into the level that this particular star represents.

Many people are not familiar with the notion that the sun itself has metals in it, which it does. Most of the sun is hydrogen and helium. Only about 2 percent of the sun are elements heavier than helium. But this star is 10 million times lower in content of its heavy metals than the sun. And so, it's as close as we've yet come to a perfectly pristine star there made out of only material processed by the Big Bang. So it's very close to that level, and hence the excitement.

MARTIN: Is that key to determining a star's age, it's the amount of metal or specifically iron that it contains?

BEERS: Yeah, iron is just shorthand for all the metals, really, because it's easy to expect in the sun. But, in fact, I should underscore that the inferred age - which is what has gotten attention from the press so far - is actually not the most important thing about this star. I would like to stress this star shows a pattern of its light elements, not just iron but carbon, magnesium and calcium, which distinguishes it as a member of a class that we refer to as carbon-enhanced metal-poor stars.


BEERS: This class of stars, which this one is the most extreme example, we believe that these stars have recorded the very first nucleus synthesis events in the universe. In other words, once stars began to form early on - after the Big Bang - we believe that they were more massive than certainly than the sun. And they only live a short period, maybe a few million years, explode and in the explosion produce a distinctive pattern. This pattern we believe is exactly what we're seeing in this star and other examples that we've discovered.

MARTIN: What are the chances of finding another star that pre-dates this one, or that possesses the same unique ingredients, for lack of a better word?

BEERS: Yes. Yeah, we actually have dedicated surveys to find carbon-enhanced metal-poor stars. This is a effort to boost up the number that have a similar pattern. I should also mention something else. This star that we're talking about today is so deficient in metals that we need to find a little bit more metal-rich stars, stars were born after this star in towards to explore that whole chemistry.

MARTIN: So the search is still on.

BEERS: The search continues.


MARTIN: Timothy Beers, of the National Optical Astronomy Observatory in Tucson, Arizon. Thank you so much for talking with us.

BEERS: Oh, it's been a pleasure, Rachel.


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