Astronomers find first white dwarf pulsar

"AR Sco is like a gigantic dynamo: a magnet, size of the Earth, with a field that is ~10.000 stronger than any field we can produce in a laboratory," said researcher Boris Gansicke.

By Brooks Hays
Astronomers find first white dwarf pulsar
An artistic rendering of the one-of-a-kind white dwarf pulsar. Photo by Warwick University

Feb. 7 (UPI) -- Astronomers at the University of Warwick have located a white dwarf pulsar -- the first of its kind.

Until now, pulsars have been the domain of neutron stars. First discovered by astronomers in the 1960s, the binary stay systems are characterized by rhythmic blasts of electromagnetic radiation.


The newly identified white dwarf pulsar is called AR Scorpii, or AR Sco. It's located in the constellation Scorpius, 380 light-years from our solar system.

When detecting pulsars, astronomers are typically observing the beam emitted by the rotating neutron star. AR Sco is different. The white dwarf's beam excites its duller companion, a red dwarf, causing the companion to suddenly glow and dim twice every two minutes.

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Astronomers have never before witnessed a combination like it.

Neutron stars and white dwarfs are similar. Both are cores of collapsed stars, or stellar remnants. But in their glory days white dwarfs were modest, sun-like stars, while neutron stars were much more massive.

AR Sco's dimensions are similar to Earth's, but it is 200,000 times more massive. Its companion is one-third the mass of the sun.

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AR Sco's white dwarf orbits its companion once every 3.6 hours. Its rotation clocks in at just less than two minutes. They're separated by 870,000 miles. When the white dwarf's electromagnetic beam blasts the red dwarf, the electrons in the companion's atmosphere are accelerated to close to the speed of light.


Scientists described the novel binary system in the journal Nature Astronomy.

"The new data show that AR Sco's light is highly polarised, showing that the magnetic field controls the emission of the entire system, and a dead ringer for similar behavior seen from the more traditional neutron star pulsars," astronomer Tom Marsh said in a news release.

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"AR Sco is like a gigantic dynamo: a magnet, size of the Earth, with a field that is ~10.000 stronger than any field we can produce in a laboratory, and it is rotating every two minutes," added researcher Boris Gansicke. "This generates an enormous electric current in the companion star, which then produces the variations in the light we detect."

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