Researchers lay claim to first find of elusive white dwarf pulsar
Starspotters at Warwick University have finally observed what they say is the first white dwarf version of a pulsar. The star AR Scorpii (AR Sco) forms a binary system along with a red dwarf that it is constantly lashing with its charged "pulses," causing the entire system to brighten and fade every two minutes. The white dwarf pulsar 380 light years from Earth is the first to be discovered since pulsars were spotted for the first time half a century ago.
Pulsars are dead stars that have collapsed in on themselves to form a neutron star, but they also spin incredibly quickly, emitting beams of electrical particles and radiation at regular intervals that can make them appear to "flash" on and off. Discovered relatively late in the history of modern astronomy, pulsars are also being investigated as a possible navigation tool in space.
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Starspotters at Warwick University have finally observed what they say is the first white dwarf version of a pulsar. Such a thing is presumed to be a rarity because white dwarfs are burned out smaller stars without enough mass to form a neutron star, which is usually much denser than a white dwarf.
But AR Scorpii (AR Sco) forms a binary system along with a red dwarf and behaves just like a pulsar. It is observed constantly lashing its companion with charged "pulses," causing the entire system to brighten and fade every two minutes.
"AR Sco is like a gigantic dynamo: a magnet, size of the Earth, with a field that is (around) 10,000 stronger than any field we can produce in a laboratory," says astrophysics professor Boris Gänsicke.
The researchers say that the stream of energy from AR Sco is a beam focused in a single direction like a particle accelerator, another first in the known universe. This has the effect of accelerating electrons in the atmosphere of its red dwarf companion to near the speed of light. In essence, the larger, cool star is powered by the kinetic energy of its spinning neighbor, something not seen in other similar binary systems.
"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 behaviour seen from the more traditional neutron star pulsars," explains professor Tom Marsh.
The research on this truly odd couple is published in Nature Astronomy.
Source: University of Warwick