By Andrew Grant
Just before a giant star blew up in a spectacular supernova explosion, it gave hints to its imminent demise. The pre-explosion activity of this star, detailed online February 6 in Nature, could enable astronomers to predict a star’s coming supernova and then watch it in real time.
“It’s a very fascinating study,” says Jon Mauerhan, an astronomer at the University of Arizona who was not involved in the research. Astronomers have only rarely witnessed the activity of a massive star before its explosion, he adds.
The star came to astronomers’ attention in August 2010 thanks to a computer program. The program scans sky survey images from a 48-inch telescope at the Palomar Observatory in Southern California and flags regions that show sudden brightening, which astronomers take as potential signs of supernovas. The researchers followed up on one such brightening 500 million light-years away and confirmed that it was a type II supernova, an explosion of a massive star whose core runs out of fuel and collapses. Then they looked at images of the same star from the prior weeks and months to see whether the star showed signs that it was about to blow.
Sure enough, they spotted a slight brightening of the fated star 37 days before its death. The scientists calculated from the brightening that the star sent a shell of gas equivalent to about one one-hundredth the mass of the sun hurtling into space at some 2,000 kilometers per second.