In a distant galaxy more than 13 billion light-years from Earth, astronomers have discovered traces of the oldest known oxygen in the universe, as well as evidence that ancient stars "turned on" as early as 250 million years after the Big Bang.
These findings, published Wednesday in Nature, suggest that star formation at the dawn of the cosmos may have been more common and robust than previously thought.
"It is not surprising that stars began to form at about that time, but what is surprising is that we found most of the stars in this galaxy were born so early," said Richard Ellis, an astrophysicist at the University College of London who contributed to the study.
"Most models suggest star formation begins gradually, not in such a single burst of activity," he added.
The ancient galaxy, known as MACS1149-JD1, was discovered in 2012, but scientists didn't know how far away — and thus, approximately how old — it was until now.
To get an accurate measurement of its distance from Earth, an international team of astronomers used the ALMA telescope in the Chilean desert to look for the signature of ionized oxygen within the light emanating from the galaxy.
"ALMA is a very sensitive observatory, and oxygen is one of the most readily detected spectrum lines in hot gas," Ellis said.