Scientists have discovered a distant star system that appears to be on the verge of a violent collapse — the kind of collapse that produces a powerful gamma ray burst. Astronomers have yet to detect a gamma-ray burst within the Milky Way galaxy.
“We discovered this star as an outlier in a survey with a radio telescope operated by the University of Sydney,” research Joe Callingham said. “We knew immediately we had found something quite exceptional: the luminosity across the spectrum from the radio to the infrared was off the charts.”
Scientists found the binary star system 8,000 light-years from Earth, within the constellation Norma. Observations suggests one of the two stars is on the threshold of a massive supernova explosion.
Researchers shared their discovery Monday in the journal Nature Astronomy.
The system consists of a pair of Wolf-Rayets, extremely hot and luminous stars. They duo orbit one another once every few hundred years.
Upon its discovery, the dramatic dust plumes surrounding the two stars caught the attention to astronomers in Australia. Researchers named the star system and its swirling dusty winds Apep after the serpentine Egyptian god of chaos.
“The curved tail is formed by the orbiting binary stars at the center, which inject dust into the expanding wind creating a pattern like a rotating lawn sprinkler,” said Peter Tuthill, professor at the University of Sydney. “Because the wind expands so much, it inflates the tiny coils of dust revealing the physics of the stars at the heart of the system.”
A closer analysis of the dust plumes and stellar winds revealed a peculiar contradiction. The swirling stellar winds were moving ten times faster than the dust.
“It was just astonishing,” Tuthill said. “It was like finding a feather caught in a hurricane just drifting along at walking pace.”
Astronomers think one of the two stars is approaching a violent death. The supernova precursor’s dramatic rotation explains the strange dynamics of the dust plumes. As Wolf-Rayet age, they increase in size, becoming increasingly unstable — threatening to explode at any moment.
“The rapid rotation puts Apep into a whole new class,” Tuthill said. “Normal supernovae are already extreme events but adding rotation to the mix can really throw gasoline on the fire.”
Such an explosion could yield a gamma ray burst, the second most powerful cosmic phenomena after the Big Bang. Fortunately, Apep isn’t pointed directly at Earth. A gamma ray burst could be powerful enough to strip ozone from Earth’s atmosphere.
Astronomers can’t yet be certain how the tale of Apep will end, but it’s a story worth watching.
“Ultimately, we can’t be certain what the future has in store for Apep,” Tuthill said. “The system might slow down enough so it explodes as a normal supernova rather than a gamma-ray burst. However, in the meantime, it is providing astronomers a ringside seat into beautiful and dangerous physics that we have not seen before in our galaxy.”
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