Doomed star on brink of rare gamma-ray burst discovered

Scientists have discovered a rare star 8,000 light years from Earth that is on the brink of a massive supernova explosion and is expected to produce a dangerous gamma-ray burst -- one of the most extreme energetic events in the universe after the Big Bang.

A gamma-ray burst has never been detected within the Milky Way galaxy before, according to the study published in the journal Nature Astronomy.

The star is a part of a system nicknamed Apep, after the serpentine Egyptian god of chaos.

It comprises two hot, luminous stars - known to astronomers as Wolf-Rayets - orbit each other every hundred years or so, according to researchers from University of Sydney in Australia.

This orbital dance is embossed on a fast wind streaming off the stars. Using spectroscopy, the astronomers have measured the velocity of the stellar winds as fast as 12 million kilometres an hour.

"We discovered this star as an outlier in a survey with a radio telescope operated by the University of Sydney," said Joe Callingham, now at the Netherlands Institute for Radio Astronomy.

"We knew immediately we had found something quite exceptional: the luminosity across the spectrum from the radio to the infrared was off the charts," said Callingham.

"When we saw the stunning dust plume coiled around the these incandescent stars, we decided to name it 'Apep' - the monstrous serpent deity and mortal enemy of Sun god Ra from Egyptian mythology," he said.

"What we have found in the Apep system is a supernova precursor that seems to be very rapidly rotating, so fast it might be near break-up," said Benjamin Pope, from New York University in the US.

Wolf-Rayet stars, like those driving Apep's plume, are known to be very massive stars at the ends of their lives. They could explode as supernovae at any time.

The researchers think this might be the recipe for a perfect stellar storm to produce a gamma-ray burst, which are the most extreme events in the Universe after the Big Bang itself.

Fortunately, Apep appears not to be aimed at Earth, because a strike by a gamma-ray burst from this proximity could strip ozone from the atmosphere, drastically increasing our exposure to UV light from the Sun.