Astronomers spot mysterious object unlike anything seen before

Researchers think the 'spooky' object could be a neutron star or a white dwarf

The Milky Way as viewed from Earth, with a star icon marking the position of the mysterious repeating transient. Natasha Hurley-Walker via AFP

A mysterious object unlike anything seen before has been observed by astronomers, who say the “spooky” body released a giant burst of energy three times an hour.

As it spins through space, the strange object sends out a beam of radiation, and for one minute in every 20 it is one of the brightest objects in the sky.

The researchers think the object could be a neutron star or a white dwarf – collapsed cores of stars – with an ultra-powerful magnetic field.

Astrophysicist Dr Natasha Hurley-Walker, from the Curtin University's International Centre for Radio Astronomy Research in Australia, led the team who made the discovery.

“This object was appearing and disappearing over a few hours during our observations," Dr Hurley-Walker said.

“That was completely unexpected. It was kind of spooky for an astronomer because there’s nothing known in the sky that does that.

“And it’s really quite close to us – about 4,000 light years away. It’s in our galactic back yard.”

She said that the observations matched a predicted astrophysical object called an “ultra-long period magnetar”.

“It’s a type of slowly spinning neutron star that has been predicted to exist theoretically," Dr Hurley-Walker said. “But nobody expected to directly detect one like this, because we didn’t expect them to be so bright.

“Somehow it’s converting magnetic energy to radio waves much more effectively than anything we’ve seen before.”

Curtin University honours student Tyrone O’Doherty discovered the object using the Murchison Widefield Array telescope in outback Western Australia – and a new technique he developed.

“It’s exciting that the source I identified last year has turned out to be such a peculiar object,” Mr O'Doherty said.

Objects that turn on and off in the universe are not new, and astronomers call them transients, with some appearing over the course of a few days and disappearing after a few months, and others flashing on and off within milliseconds or seconds.

But Curtin astrophysicist and co-author Dr Gemma Anderson said finding something that turned on for just a minute made the discovery unusual.

Dr Anderson said the mysterious object was incredibly bright and smaller than the sun, emitting the kind of radio waves that suggested it had an extremely strong magnetic field.

The researchers are now monitoring the object to see if it switches back on, and plan to search for more of these unusual objects in the vast archives of the Array.

“More detections will tell astronomers whether this was a rare, one-off event or a vast new population we’d never noticed before,” Dr Hurley-Walker said.

The object was visible through a radio telescope and could not be seen with the naked eye. The findings are published in the Nature journal.