A massive space blast went unspotted last year because it was hidden by a huge cloud of dust, scientists revelaled today. The explosion – caused when a star blew itself to bits – was the closest to Earth for five years and would normally have been easily visible to stargazers.
But dense dust and gas between it and us blocked the view. Instead the supernova, in a relatively nearby galaxy called M82 in Ursa Major, was detected by radio telescopes which were able to listen in despite the dusty barrier.
The irregularly shaped galaxy lies 12 million light-years away, which is relatively close on the cosmic scale of things. It is famous for housing a giant stellar nursery at its centre where more new stars are being born than in our own entire Milky Way galaxy.
The death of an old star in a supernova blast was long overdue in M82. Astronomers had been watching out for one there for a quarter of a century.
The discovery of the invisible supernova was made last month using a giant network of radio telescopes called the Very Large Array in New Mexico. Dr Andreas Brunthaler, of Germany’s Max Planck Institute, who made the find, then looked back at old data and found evidence that it had actually become brighter than the entire galaxy in spring 2008.
Photos with optical telescopes last year show no sign of the incredible blast thanks to the blanket of dust lying in the way. Colleague Professor Heino Falcke from Radboud University, Nijmegen, in the Netherlands, said: “This cosmic catastrophe shows that using our radio telescopes we have a front-row seat to observe the otherwise hidden universe.”
By combining observations from radio telescopes around the world, the team found the blast had thrown out a ring of debris speeding through space at more than 25 million mph. (40million kph). Tracing it back showed that the star must have exploded in late January or early February 2008.
Last year, astronomers were lucky enough to catch a supernova exploding in another galaxy 90 million light-years away. They have also identified stars primed to explode in our own Milky Way.
New: Read the Max Planck Institute’ s press release on our new Space Ticker service.
Picture: A Hubble space telescope photo of galaxy M82 plus three radio images pinpointing the blast and showing how a ring of debris has expanded. (HST Image: /NASA, ESA, and The Hubble Heritage Team (STScI/AURA); Radio Images: A. Brunthaler, MPIfR.)