THE astronomers were looking for something dark.
Dark matter. Dark energy.
Essentially, it’s the 80 per cent of the universe we know should be there — but we can’t see.
Instead, they found something bright.
Some 72 intense bursts of light.
Not the bright sustained flare of a star going nova over the course of several months.
But a short, sharp — immense — flash.
The University of Southampton presented the results of its Dark Energy Survey Supernova Program (DES-SN) at the European Week of Astronomy and Space Science earlier this week.
Astronomer Miika Pursiainen had been using the 4-meter telescope of the Cerro Tololo International Observatory in Chile.
He was gathering data on the rate of expansion of the universe, and what this implies for the ‘missing mass’ the universe must contain.
“The DES-SN survey is there to help us understand dark energy, itself entirely unexplained,” Pursiainen said. “That survey then also reveals many more unexplained transients than seen before.”
What he and his team saw were hot blasts of between 10,000C and 30,000C. These flares started at 300 million kilometres across, but some reached out up to 15 billion kilometres..
Their brightness was similar to that of a supernova.
But their duration was much too short.
Pursianen is still trying to figure out what the strange cosmic events represent.
Among his first thought was that these flashes are not the star itself exploding. Instead, it could be shedding its skin as it slowly goes through its death throes.
As a star ages, heavy elements build up among its core. These eventually grows so heavy that the star collapses in on itself, in the process blowing-off its outer shell of gas.
Its known as a Type II supernova.
These new short flashes could represent a complication of this process.
The star could have blowing out clouds of gas during earlier stages of its collapse. Once the star actually starts to go supernova, these big bubbles could become superheated — and explode.
But the Australian National University (ANU) is already working on understanding exactly that concept. It’s been looking at the unusual explosion of a star caught by the Kepler space telescope.
It was cocooned inside a dense shell of gas.
When the massive amount of energy from the supernova slammed into the shell, most of the kinetic energy was immediately converted to light, the ANU team says.
The final explosion of the star, which was about 1.3 billion light years away from Earth, lasted for only a few days – 10 times faster than a typical supernova.
It’s been named a fast-evolving luminous transient (FELT).
“We’ve discovered yet another way that stars die and distribute material back into space,” ANU Research School of Astronomy and Astrophysics researcher Brad Tucker said.
At the moment, that this is what the Dark Energy Survey team saw is just a working theory. More observations and analysis are needed to give it substance.
“If nothing else, our work confirms that astrophysics and cosmology are still sciences with a lot of unanswered questions,” Pursiainen said.