A distant pulsar is taking it slow 鈥� so slow that it shouldn鈥檛 exist. Radio pulsars are rapidly-spinning neutron stars that emit a beam of powerful radio waves, and we鈥檝e just found one rotating so slowly that its beam should have been snuffed out.
Chia Min Tan at the University of Manchester, UK and his colleagues found this sluggish star using the Low-Frequency Array (LOFAR), a set of radio telescopes based mostly in the Netherlands.
This pulsar, called PSR J0250+5854, takes 23.5 seconds to complete a rotation. That might sound pretty swift, but it is actually the slowest radio pulsar ever spotted 鈥� most others have rotation periods in the single digits.
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Given that we have seen one of these slow pulsars, there are probably many more out there, Tan says, but they are difficult to find.
鈥淭he radio that comes from a pulsar is sort of like a lighthouse 鈥� you can only see the signal if the radio beam points towards you,鈥� says Tan. 鈥淔or a longer period pulsar we expect the beam to be much narrower compared to a faster pulsar, so we expect these to be harder to detect.鈥�
But according to our current understanding of how pulsars generate their beams, these slow ones should not exist at all. The way that we think pulsars create radio waves depends on charged particles being accelerated by the neutron star鈥檚 magnetic field as it spins, and this one seems to be spinning too slowly.
Alice Harding at NASA鈥檚 Goddard Space Flight Center in Maryland says this may point to the magnetic field being more complicated than those at most stars. 鈥淵ou definitely would not be able to create this pulsar without some significant additional distortion of the magnetic field,鈥� she says.
This pulsar may help us figure out exactly how others like it generate their beams, and why they stop, says Jim Cordes at Cornell University in New York. 鈥淲e鈥檇 need a few hundred of them, but this may be the harbinger of that population of very slow-moving objects.鈥�
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