Astronomers watched a neutron star 'glitch' and can't yet explain it

A glitch in the cosmos.

Jackson Ryan Former Science Editor
Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, he realized, was the best job in the world -- it let him tell stories about space, the planet, climate change and the people working at the frontiers of human knowledge. He also owns a lot of ugly Christmas sweaters.
Jackson Ryan
3 min read
Pulsar image

A pulsar is a rapidly spinning star that, from Earth, appears to "pulse" with light. Makes sense.

NASA's Goddard Space Flight Center

You remember that part in the (now 20-year-old) film The Matrix where Neo looks at a black cat and then seconds later, he sees the same black cat again? And he's all like "I just had deja vu but it's OK" but it's actually not OK at all? Well, as if providing evidence that we, too, exist in the Matrix, a team of international astronomers has been watching the rapidly spinning corpse of a star -- and while they were watching, they saw it "glitch."

While there's no definitive evidence that we live in a simulation (sorry, Elon Musk), astronomers are puzzled by this glitch, a phenomenon they've known about for the past 50 years but still haven't quite worked out. A study, published Monday in the journal Nature Astronomy, specifically looks at the Vela pulsar, a type of neutron star. It's one of the best-known pulsars in the sky and also the brightest. 

In 2016, astronomers recorded the glitch in Vela, and the new research, led by Gregory Ashton of Monash University in Australia, puts that glitch under the microscope, detailing how it came about and what led to it. Ashton said the glitch gives researchers "a unique opportunity to peer inside these objects and understand what is going on."

To understand why it's such a big deal, we have to understand what a pulsar really is.

A neutron star is one of the final stages of a star's life. After a star collapses, goes supernova and explodes, a neutron star is the small leftover remnant in its place -- and it's super weird. A neutron star has the same mass as our sun, but it's all wrapped up in a much smaller physical space of about 20 kilometers (12.4 miles) in diameter. Those two features make it one of the densest objects in the universe. The star is also rapidly spinning -- in the case of the Vela pulsar, it rotates about 10 times every second.

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"As the neutron star rotates, it emits a beam of electromagnetic radiation, like a lighthouse," Ashton said. "This lighthouse sweeps out and, if it passes of the Earth, is recorded by radio astronomers."

Those pulses of electromagnetic radiation give the pulsar its name, and we can pick up the intermittent signal down here on Earth.

"Gradually, the stars slow down due to torques in much the same way that if you turn a bike over and spin the wheel, it will gradually slow down due to friction of the bearings," Ashton explained. But every now and again the pulsars glitch and don't slow down. Instead, they speed up. Ashton said this effect is small but detectable and these glitches aren't new. However, on this occasion, a team at the University of Tasmania were able to record this event as it happened in 2016.

Ashton's team reanalyzed the data gathered by the previous study and confirmed the glitch, showing Vela did speed up and then settled into a spin.

They also found one utterly perplexing result: The neutron star experienced an unexpected slowdown slightly before it spun back up. They dub this a precursor "antiglitch," just to make things a little more confusing. Ashton posits one theory, that the slowing down itself may be the cause of the glitch but ultimately, the team is still unsure how this might occur.

"There are a great many mysteries surrounding neutron stars, including why they glitch in the first place," Ashton said. "While we have had 50 years to figure this out, we still do not have a conclusive answer. We hope with this work that we have opened up a new avenue and sparked some new ideas."

Ashton says an undergraduate student will reanalyze the details of the event in a new way, which he hopes will untangle the story. For now, I'm taking that as good news: We aren't living in a simulation and we didn't just see a glitch in the Matrix.

I hope.

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