Scientists see giant, powerful flare coming from nearby star

Artist's impression of a magnetar (ESA)
Artist's impression of a magnetar (ESA)

Scientists have seen a sudden explosion coming from a rare object in a nearby galaxy.

Researchers believe that the burst must be giant flare erupting out of a magnetar, a kind of neutron star. It offers an opportunity to study an incredibly rare event – and could help explain other kinds of unusual activity in the universe.

Such giant flares are so unusual that we have only seen three of them in our galaxy and the nearby Large Magellanic Cloud in the last 50 years. Seeing them from further away can be difficult because it is hard to know where they are coming from.

Those giant flares can be incredibly powerful. In 2004, one hit us from 30,000 light years away but was still able to affect the Earth’s atmosphere.

Late last year, the European Space Agency’s INTEGRAL satellite spotted what appeared to be an explosion in part of the sky. For just a tenth of a second, the sky was lit with a burst of energetic gamma-rays.

Astronomers across the world were sent an urgent alert about the event, which arrived just 13 seconds later. It showed that it had come from the galaxy M82, which is relatively nearby at 12 million light-years away.

“We immediately realised that this was a special alert. Gamma-ray bursts come from far-away and anywhere in the sky, but this burst came from a bright nearby galaxy,” said Sandro Mereghetti of the National Institute for Astrophysics (INAF–IASF) in Italy, who led the work on the new study.

Researchers quickly rushed to examine the location of the burst, expecting that they might see the gravitational waves and glow of X-rays and light that are usually left behind when two neutron stars collide.

But they could only see hot gas and stars. There were no X-rays or light signals to be seen, and no gravitational waves.

That led researchers to believe that the signal came from a magnetar, a kind of neutron star with a particularly powerful magnetic field. They throw out flares – which are sometimes huge, but very rarely.

It is the first firm confirmation of such a magnetar flare having come from outside of our own Milky Way galaxy. It came from M82, a bright galaxy that is forming stars in a churning process that sees them born, and then quickly live violent lives that end in a neutron star.