Astronomers using the Murchison Widefield Array (MWA) telescope have discovered a spinning object that pulses every 18.18 minutes; they’ve localized the radio source to within our own Milky Way Galaxy and suggest that it could be an ultra-long-period magnetar.
An artist’s impression of what the object might look like if it’s a magnetar. Image credit: ICRAR.
“This object was appearing and disappearing over a few hours during our observations,” said Dr. Natasha Hurley-Walker, an astronomer with the Curtin University node of the International Centre for Radio Astronomy Research.
“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 backyard.”
“It’s exciting that the source I identified last year has turned out to be such a peculiar object,” added Tyrone O’Doherty, a Ph.D. student at Curtin University.
“The MWA’s wide field of view and extreme sensitivity are perfect for surveying the entire sky and detecting the unexpected.”
Objects that turn on and off in the Universe aren’t new to astronomers — they call them transients.
Slow transients — like supernovae — might appear over the course of a few days and disappear after a few months.
Fast transients — like a type of neutron star called a pulsar — flash on and off within milliseconds or seconds.
“Finding something that turned on for a minute was really weird,” said Dr. Gemma Anderson, an astrophysicist with the Curtin University node of the International Centre for Radio Astronomy Research.
“The mysterious object was incredibly bright and smaller than the Sun, emitting highly-polarized radio waves — suggesting the object had an extremely strong magnetic field.”
“The observations match 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,” she added.
“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.”
The team is now monitoring the object with the MWA to see if it switches back on.
“If it does, there are telescopes across the southern hemisphere and even in orbit that can point straight to it,” Dr. Hurley-Walker said.
The team’s paper was published in the journal Nature.
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N. Hurley-Walker et al. 2022. A radio transient with unusually slow periodic emission. Nature 601, 526-530; doi: 10.1038/s41586-021-04272-x
Source link: https://www.sci.news/astronomy/ultra-long-period-magnetar-10496.html
