A group of scientists at the University of Warwick have discovered the first white dwarf pulsar ending a search that has lasted over fifty years. The pulsar was found in the neighbouring system of AR Scorpii an exotic binary star system nearly 400 light years away in the Scorpius constellation.

The binary star system is comprised of two Suns rapidly orbiting each other so fast that they complete a single orbit in just 3.6 hours. One of the stars is a more commonly seen red dwarf that is about one third of a solar mass (one solar mass being the same as our Sun). Similar to our Sun, is red dwarf uses hydrogen for its fuel.

The second star in the system is however much rarer, it is a white dwarf pulsar. This is approximately the same size as Earth but it is 200,000 times denser. While other pulsars have been discovered, white dwarf pulsars a unique in the way they form. Neutron stars and pulsars are the naked core of a much larger star that has been compressed when becoming a supernova. The compression is so powerful that individual atoms fuse together leaving no space for orbiting electrons.

This is the densest a star can seemingly get without becoming a black hole. The white drawn pulsar is smaller however and far less dense. It is formed when the sun runs out of fuel and the outer layers are stripped away into space. What’s left of the sun, the core, contracts into a sphere the size of Earth but with the same mass as our sun. Neutron stars tend to be denser managing to fit the same mass into a star approximately the size of a city. Pushes are similar but they have the effect of giving off beams of radio and x-ray pulses like a colossal fast spinning lighthouse.

White white dwarf stars often cool down to eventually become black dwarf stars, this white dwarf pulsar has retained enough energy that, just like a neutron star, it can produce a powerful magnetic field and emit high energy pulses.

Due to this massive magnetic field, roughly 100 million times more powerful than that of Earth, radiation and charged particles are accelerated out from the star poles in powerfully focused beams. These beams occasionally hit the neighboring red dwarf star causing the entirely star system to beautifully light up and then fade. As the dwarf star makes a full rotation exceptionally quickly, these flashes occur every two minutes!

Impressively, these stars also orbit each other at 1.4 million km which is only three times greater than the distance between the Earth and the Moon and one hundred times smaller than the distance between he Earth and the Sun.

For further reading the published article in Nature can be found at: http://www.nature.com/articles/s41550-016-0029


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