Astronomers Baffled by Unusually Slow Pulsar, Defying Current Theories with Its Impossible 54-Minute Spin
TL;DR
Astronomers have detected an exceptionally slow-spinning neutron star, ASKAP J1935+2148, which emits a radio signal every 54 minutes, making it the slowest known pulsar. This discovery challenges existing theories that pulsars need to spin much faster to emit radio waves. Researchers observed three distinct emission states, suggesting potential physical changes in the star’s environment. The possibility that this object could be a white dwarf adds further mystery, as no similar stars have been observed nearby. Further study might upend our understanding of stellar remnants like neutron stars and white dwarfs.
After reading the article, a Reddit user gained more than 486 upvotes with this comment: “Lots of things in space have a periodic signal—the most famous, of course, are pulsars, which are neutron stars that spin rapidly and emit a radio beam, leading us to see a radio ‘pulse’ every few seconds (or less!) as the pulsar spins and the beam passes. The longest pulsar period to date is just a few seconds long—still a prodigious speed when you remember it’s an object with the mass of the sun squeezed into ~10km or so—and it’s thought theoretically this occurs because a pulsar needs to spin once every few seconds, because if it doesn’t it can no longer sustain its radio beam and the pulsar switches ‘off.’ This process is thought to take about 10.” Discuss in the comment section below!
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Radio Star
Scientists are perplexed by a repeated radio signal from outer space since they are unable to adequately explain what is causing it.
Their working hypothesis, as outlined in a research published in the journal Nature Astronomy, is that the source is most likely a pulsar, a kind of neutron star that emits radio waves as it rotates on its axis.
However, if accurate, this raises even more issues. ASKAP J1935+2148, the slowest spinning neutron star yet observed, has a 54-minute interval. It’s so slow that it should be impossible, adding to a tiny but increasing list of seemingly inexplicable stellar remains.
“It is highly unusual to discover a neutron star candidate emitting radio pulsations in this way,” said research lead author Manisha Caleb of the University of Sydney Institute for Astronomy in a statement about the study. “The fact that the signal is repeating at such a leisurely pace is extraordinary.”
Speed Demon
Neutron stars arise in the aftermath of a supernova, which is an epic explosion that occurs when a large star runs out of fuel and collapses due to its own gravity.
Whatever material is not ejected into space is compressed into a fraction of the star’s initial size, making them the densest things in the universe that are not black holes.
Neutron stars also have extremely high magnetic fields, which propel streams of particles into space along their poles. When pulsars spin, these particle streams rotate as well, giving astronomers the impression that this is a repeating signal.
ASKAP J1935+2148 appears to match the criteria, however it’s unlikely that a neutron star can spin that slowly and yet emit pulses. To give you a sense of how unusual this is, pulsars usually complete a rotation in a matter of seconds, if that. Meanwhile, the fastest known neutron star spins at a staggering 716 times every second.
Stellar Spin-Off
The strange item also has three separate emission states, “each with properties entirely dissimilar from the others,” Caleb stated. There are powerful radio signals that last 10 to 50 seconds, followed by a lesser condition in which it produces a 26-times fainter pulse that lasts only a third of a second, and lastly a quiescent state.
Over the course of eight months, the researchers discovered that the active emission states were changing, implying that there may be physical changes in the region that is causing the emissions.
If it is not a neutron star, the researchers believe it might be a white dwarf, the most common sort of stellar remnant with a strong magnetic field. This option, however, raises questions: if the white dwarf is indeed magnetic, astronomers should have found others nearby due to their strength. But so yet, no one has been.
Further research of the item, Caleb stated, “might even prompt us to reconsider our decades-old understanding of neutron stars or white dwarfs; how they emit radio waves and what their populations are like in our Milky Way galaxy.”
Lots of things in space have a periodic signal- the most famous of course are pulsars, which are neutron stars that spin rapidly and emit a radio beam, leading us to see a radio “pulse” every few seconds (or less!) as the pulsar spins and the beam passes. The longest pulsar period to date is just a few seconds long- still a prodigious speed when you remember it’s an object with the mass of the sun squeezed into ~10km or so- and it’s thought theoretically this occurs because a pulsar needs to spin once every few seconds, because if it doesn’t it can no longer sustain its radio beam and the pulsar switches “off.” This process is thought to take about 10 million years or so as the pulsar slows down, btw, meaning 99% of neutron stars are no longer detectable.
Now, this signal looks exactly like a pulsar, except it’s only pulsing once every 54 minutes. So the discovery paper actually suggests a really slow pulsar as a possibility for this signal! (This would be amazing if shown to be true, and challenge a ton of existing theoretical models for pulsars.) Another suggestion is that it could be a very unusual white dwarf- the core of a dead star like what the sun will be someday- which in this case is highly magnetized and interacting with something else. But we definitely don’t know the truth for sure.
In broader context, though, it’s worth noting that finding unusual signals that repeat in weird time scales isn’t that unusual and happens somewhat often in radio astronomy. Less than a year ago, another group discovered a pulsar-like signal that blinks every 22 minutes, for example. My favorite example, called “The Great Galactic Burper,” was observed to burst 10 minutes every 77 minutes (link), and did so for several years, but hasn’t been recorded since 2007. No one knows what caused it! Lots of weird things that go bump in the night that we don’t yet understand… which is what makes radio astronomy so exciting and fun!
Scientists baffled at astronomers being puzzled at straaaaaange un-explained phenomena that is widely incomprehensible by doctors everywhere being confused at this odd new discovery that has archeologists flabbergasted at why the possible thing is there!
I’m going to guess it’s probably a Nissan Pulsar.
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