A massive explosion spotted 200 million light years from Earth has baffled astronomers. The strange spot, nicknamed ‘the cow’, is up to 100 times brighter than a supernova and is growing at an incredible rate. Scientists say the flash is a 9,000°C (16,000°F) cloud of high-energy particles bursting outwards at 12,000 miles (20,000km) per second, but are still unsure what triggered the brilliant blast. One researcher said ‘there hasn’t been another object like this.’ The explosion was captured on by the asteroid-tracking ATLAS telescopes at the Keck Observatory, which sits atop Mauna Kea, a dormant volcano in Hawaii. Astronomers noted the flash was unusually luminous – between 10 and 100 times brighter than the average supernova – but it was the speed of its appearance that caught the eye of space experts. Most celestial explosions take weeks to reach peak brightness, but the distant flash had grown to a dramatic size in just two days.
‘It just appeared out of nowhere,’ Dr Kate Maguire, an astronomer at Queen’s University Belfast who is part of the ATLAS team, told New Scientist. ‘There are other objects that have been discovered that are as fast, but the fastness and the brightness, that’s quite unusual. There hasn’t been another object like this.’ Following the initial observation, scientists reported the flash to the star-gazing website Astronomer’s Telegram, sparking a worldwide investigation into the spot. It was nicknamed the cow after the site automatically categorised it as AT2018cow based on when it was added to the database. Teams from around the world trained at least 18 telescopes on the flash in a response that constituted the largest number of reports for any single object on Astronomer’s Telegram, according to the site’s Editor-in-Chief.
The explosion was so bright it initially appeared to originate from our galaxy, but observations by a group of Chinese scientists showed the spot was almost 200 million light years away – meaning it likely appeared in another nebula. Readings from other groups suggested the flash was an explosion of high-energy particles travelling outwards at 12,000 miles (20,000km) per second. The surface temperature of this cloud could be as high as 9,000°C (16,000°F), according to the observations. The results left scientists baffled as to the origins of the strange explosion, with some suggesting it could be a special type of supernova called a type 1c. ‘We’re not sure yet what it is, but the normal powering mechanism for a supernova is the radioactive decay of nickel, and this event is too bright and too fast for that,’ Dr Maguire said. Follow-up observations are ongoing, and scientists said they should know more about the object over the next day or two.
Credit: Harry Pettit for MailOnline, 22 June 2018.