A distant, ancient cloud of gas discovered by Swinburne University scientists may contain the signature of the first stars that ever formed in the universe. The cloud possesses a very small percentage of heavy elements, such as carbon and oxygen (less than one thousandth of the amount contained in the sun), and is located billions of light-years away from the Earth.
"Heavy elements weren't manufactured during the Big Bang, they were made later by stars," said Neil Crighton, lead researcher of the study, in a press release. "The first stars were made from completely pristine gas, and astronomers think they formed quite differently from stars today."
After their formation, the researchers believe that these ancient stars, referred to as Population III stars, exploded in a supernovae that threw all of their heavy elements into surrounding clouds of gas and these clouds subsequently carried the chemical mark of these dead stars like a fingerprint.
"Previous gas clouds found by astronomers show a higher enrichment level of heavy elements, so they were probably polluted by more recent generations of stars, obscuring any signature from the first stars," said Crighton.
The discovery marks the first cloud to show the small percentage of heavy elements that would be expected for one that was only enriched by ancient stars. In the future, the researchers hope to find more of these systems so they can measure the ratios of their various elements
"We can measure the ratio of two elements in this cloud, carbon and silicon. But the value of that ratio doesn't conclusively show that it was enriched by the first stars; later enrichment by older generations of stars is also possible," said John O'Meara, co-author of the study. "By finding new clouds where we can detect more elements, we will be able to test for the unique pattern of abundances we expect for enrichment by the first stars."
The findings will be published in the Jan. 13 issue of Monthly Notices of the Royal Astronomical Society and the pre-print can be accessed HERE.
