Dead star 10 mn times brighter than Sun discovered

Using NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), astronomers have found a pulsating, dead star beaming with the energy of about 10 million Suns.

This is the brightest pulsar - a dense, stellar remnant left over from a supernova explosion - ever recorded.

"You might think of this pulsar as the 'Mighty Mouse' of stellar remnants. It has all the power of a black hole but with much less mass," said Fiona Harrison, the NuSTAR principal investigator at the California Institute of Technology,Pasadena in the US.

The surprising find is helping astronomers better understand mysterious sources of blinding X-rays known as ultra-luminous X-rays (ULXs).

Until now, all ULXs were thought to be black holes.

The new data from NuSTAR shows that at least one ULX - about 12 million light-years away in the galaxy Messier 82 (M82) - is actually a pulsar.

"The pulsar appears to be eating the equivalent of a black hole diet. This result will help us understand how black holes gorge and grow so quickly which is an important event in the formation of galaxies and structures in the universe," Harrison added.

Pulsars belong to a class of stars called neutron stars.

Like black holes, neutron stars are the burnt-out cores of exploded stars but puny in mass.

Pulsars send out beams of radiation ranging from radio waves to ultra-high energy gamma rays.

As the star spins, these beams intercept Earth like lighthouse beacons, producing a pulsed signal.

The discovery appeared in the journal Nature.

Astronomers are planning follow-up observations with NASA's NuSTAR, Swift and Chandra spacecraft to find an explanation for the pulsar's bizarre behaviour.