麻豆直播

A team mapping radio waves in the Universe has discovered something unusual that releases a giant burst of energy three times an hour, and it鈥檚 unlike anything astronomers have seen before.

The team who discovered it think it could be a neutron star or a white dwarf鈥攃ollapsed cores of stars鈥攚ith an ultra-powerful magnetic field.

Spinning around in space, the strange object sends out a beam of radiation that crosses our line of sight, and for a minute in every twenty, is one of the brightest radio sources in the sky.

Astrophysicist Dr Natasha Hurley-Walker, from the 麻豆直播 node of the International Centre for Radio Astronomy Research, led the team that made the discovery.

鈥淭his object was appearing and disappearing over a few hours during our observations,鈥� she said.

鈥淭hat was completely unexpected. It was kind of spooky for an astronomer because there鈥檚 nothing known in the sky that does that.

鈥淎nd it鈥檚 really quite close to us鈥攁bout 4000 lightyears away. It鈥檚 in our galactic backyard.鈥�

The object was discovered by 麻豆直播 Honours student Tyrone O’Doherty using the Murchison Widefield Array (MWA) telescope in outback Western Australia and a new technique he developed.

鈥淚t鈥檚 exciting that the source I identified last year has turned out to be such a peculiar object,鈥� said Mr O鈥橠oherty, who is now studying for a PhD at Curtin.

鈥淭he MWA鈥檚 wide field of view and extreme sensitivity are perfect for surveying the entire sky and detecting the unexpected.鈥�

Objects that turn on and off in the Universe aren鈥檛 new to astronomers鈥攖hey call them 鈥榯ransients鈥�.

ICRAR-Curtin astrophysicist and co-author Dr Gemma Anderson said that 鈥渨hen studying transients, you鈥檙e watching the death of a massive star or the activity of the remnants it leaves behind.鈥�

鈥楽low transients鈥欌�攍ike supernovae鈥攎ight appear over the course of a few days and disappear after a few months.

鈥楩ast transients鈥欌�攍ike a type of neutron star called a pulsar鈥攆lash on and off within milliseconds or seconds.

But Dr Anderson said finding something that turned on for a minute was really weird.

She said the mysterious object was incredibly bright and smaller than the Sun, emitting highly-polarised radio waves鈥攕uggesting the object had an extremely strong magnetic field.

Dr Hurley-Walker said the observations match a predicted astrophysical object called an 鈥榰ltra-long period magnetar鈥�.

鈥淚t鈥檚 a type of slowly spinning neutron star that has been predicted to exist theoretically,鈥� she said.

鈥淏ut nobody expected to directly detect one like this because we didn鈥檛 expect them to be so bright.

鈥淪omehow it鈥檚 converting magnetic energy to radio waves much more effectively than anything we鈥檝e seen before.鈥�

Dr Hurley-Walker is now monitoring the object with the MWA to see if it switches back on.

鈥淚f it does, there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it,鈥� she said.

Dr Hurley-Walker plans to search for more of these unusual objects in the vast archives of the MWA.

鈥淢ore detections will tell astronomers whether this was a rare one-off event or a vast new population we’d never noticed before,” she said.

MWA Director Professor Steven Tingay said the telescope is a precursor instrument for the Square Kilometre Array鈥攁 global initiative to build the world鈥檚 largest radio telescopes in Western Australia and South Africa.

鈥淜ey to finding this object, and studying its detailed properties, is the fact that we have been able to collect and store all the data the MWA produces for almost the last decade at the Pawsey Research Supercomputing Centre. Being able to look back through such a massive dataset when you find an object is pretty unique in astronomy.鈥� he said.

鈥淭here are, no doubt, many more gems to be discovered by the MWA and the SKA in coming years.鈥�