12:28 30 June 2015
An enormous black hole called the V404 Cygni system has “woken up” after 26 years, offering a rare opportunity for astronomers.
The V404 Cygni system is about 8,000 light years away from Earth in the Milky Way galaxy and is made up of a black hole and a star, which orbit each other. Material flows from the stars to the black hole, where it gathers in a disc and heats up, before going towards the hole.
For the past ten days, repeated bright flashes of light has been observed from the system, something that is rarely seen in other black hole systems. Each time this happens, the system becomes the brightest object in the X-ray sky – up to 50 times brighter than the Crab Nebula, which is usually one of the brightest sources in the sky.
Erik Kuulkers, from the European Space Agency (ESA), which describes V404 Cygni as a "monster black hole", said: "The community couldn't be more thrilled.
"Many of us weren't yet professional astronomers back then, and the instruments and facilities available at the time can't compare with the fleet of space telescopes and the vast network of ground-based observatories we can use today.
"It is definitely a 'once in a professional lifetime' opportunity."