Astronomers have traced the solar flare to a “puny” brown dwarf star some 250,000 light-years away from Earth. The star, known as ULAS J224940.13-011236.9, is comparable in size to the gas giant Jupiter and is only a tenth of the Sun’s radius. But when the flare exploded, astronomers saw the star suddenly flash 10,000 times brighter than normal. The incredible discovery was published on Wednesday, April 17, in the Monthly Notices of the Royal Astronomical Society: Letters.
Professor Peter Wheatley, who supervised the discovery at the University of Warwick, was amazed by the raw power on display.
He said: “It is amazing that such a puny star can produce such a wonderful explosion.
“This discovery is going to force us to think again about how small stars can store energy in magnetic fields.
“We are no searching giant flares from other tiny stars and push the limits on our understanding of stellar activity.”
The brown dwarf by all standards is a minuscule star – barely bright enough for most telescopes to pick up.
But on August 13, 2017, the star spewed energy to the tune of 80 billion megatonnes of TNT.
The solar flare was at least 10 times more potent than the infamous 1859 Carrington event, which to date, remains the most powerful solar flare ejected by our Sun.
The solar storm of 1859 was so powerful it set telegraph equipment on fire and produced glowing aurora effects as far as Cuba and Australia.
Solar flares are a regular occurrence on the Sun and are large ejections of electromagnetic radiation from the star.
Major flares in space can cause widespread chaos by disrupting radio signals, power grids and satellite operations.
However, Warwick’s astronomers were stunned to see a star as small as ULAS J224940.13-011236.9 produce a flare this powerful.
Lead author James Jackman, a PhD student at Warwick, said: “We knew from other surveys that this kind of star was there and we knew from previous work that these kinds of stars can show incredible flares.
“However, the quiescent star was too faint for our telescopes to see normally – we wouldn’t receive enough light for the star to appear above the background from the sky.
“Only when it flared did it become bright enough for us to detect it with our telescopes.”
Professor Wheatley added: “Our twelve NGTS telescopes are normally used to search for planets around bright stars, so it is exciting to find that we can also use them to find giant explosions on tiny, faint stars.
“It is particularly pleasing that detecting these flares may help us to understand the origin of life on planets.”