Dead star comes back to life in 'never seen before' event

Scientists have been surprised by a dead star which appears to have sprung back to life.

Researchers using a radio telescope say they noticed "unusual" radio pulses coming from the star, which has a powerful magnetic field.

It's a type of neutron star and one of the strongest magnets in the universe called a magnetar.

It's roughly 8,000 light years away and is the closest known magnetar to Earth.

Stars are only able to survive as long as they have a supply of a chemical element called hydrogen to burn.

Once they've used up their fuel they become white dwarf stars, neutron stars or black holes, depending on how big and heavy they are.

This star, known as XTE J1810-197, was first seen giving out radio signals in 2003. It then went silent for more than 10 years.

The signals were detected again by the University of Manchester's Lovell telescope in 2018 and then by the Murriyang Parkes radio telescope, which has been observing the magnetar's radio emissions ever since.

Detecting radio pulses from magnetars is already extremely rare: XTE J1810-197 is one of only a handful known to produce them.

It's not only the fact the star has sprung back to life that has amazed scientists, but also the type of light the star is releasing.

The light from the magnetar appears to spiral as it moves through space.

Dr Marcus Lower from Australia's national science agency CSIRO led the latest research and said the results are "unexpected".

While it's not certain, the team believes it might come down to something called superheated plasma.

Plasma glows in the form of stars, nebulas, and even the auroras that sometimes are seen above the north and south poles.

"Our results suggest there is a superheated plasma above the magnetar's magnetic pole, which is acting like a polarising filter," Dr Lower said.

A polarising filter means only some of the light is let out in certain directions.

It is yet to be discovered how the plasma is doing this.