The ultimate age barrier has been broken. The oldest living star in the entire universe may have been discovered—one formed only one or two hundred million years after the Big Bang itself.
The ancient star, born some 13.6 billion years ago, bests the previous record handily, by 400 million years, and offers a unique view into what the universe looked like soon after its birth.
“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” said the lead author of the new study, astronomer Stefan Keller of the Australian National University Research School of Astronomy and Astrophysics.
“What this star has enabled us to do is record the fingerprint of those first stars.”
The record-breaker was first spotted as part of a million-star survey using the SkyMapper Telescope at the Australian National University’s Siding Spring Observatory in New South Wales, Australia. In high-resolution follow-up observations by the Magellan Telescopes in Chile, astronomers next noticed that one faint star, called SMSS J031300.36-670839.3, possessed unusually low levels of heavy metals such as iron.
According to current theories, astronomers can estimate the age of stars by the amount of iron that they contain. The unexpected lack of metal in the aged star indicates it was born out of the remnants of a very short-lived, primordial supernovae that had a mass 60 times that of our sun’s.
“What happened was that one first star dies in a supernova and then the gas that was thrown out mixed in with the surrounding pristine gas. Then later that gas cooled and formed a star. And so this is the star we are observing now,” said Keller.
What is puzzling researchers is that these first-generation supernovae blasts were thought to pollute their surroundings with a lot of iron.
But these new findings show that this ancient star shows no sign of these pollutants.
“This indicates the primordial star’s supernova explosion was of surprisingly low energy. Although sufficient to disintegrate the primordial star, almost all of the heavy elements, such as iron, were consumed by a black hole that formed at the heart of the explosion,” said Keller.
Galaxy Building Block
The new stellar old-timer calls our own Milky Way galaxy home, and it is located just 6,000 light-years away in the far southern constellation Dorado. But it is thought to be even older than the galaxy.
Keller and his team believe that the stellar old-timer may have formed in an isolated gas blob in the early universe. Later on, it was incorporated into our galaxy.
“Stars are like time capsules; they lock away a chunk of the universe as it was when the star formed,” he says. “This is an important time in the evolution of the universe—our Milky Way is formative, the first stars have switched on, and the first heavier elements, which we need for life, are starting to disperse.”
Even with the largest telescopes, we have not yet been able to study the light directly from this time, he adds.
See for Yourself
Despite its age, the ancient star can still be spotted from the Southern Hemisphere with a large backyard telescope.
Because the star glows at a feeble 14.7 magnitude, Keller estimates that to see it visually a sky-watcher will need to peer skyward under dark skies through an instrument at least 16 to 20 inches. However, much more modest scopes outfitted with digital cameras should have an easier time capturing the star’s subtle glimmer.
Even if you don’t have the astro-gear to hunt this cosmic old-timer down for yourself, it’s amazing to just look up at this one spot in the sky and ponder that this intriguing record-breaker lies in our own galactic backyard.
The discovery study was released by the journal Nature.