Science News

Supernova is the star of the show

Scientists in the US, writing in this week's Nature, have caught the first glimpse of a star blowing itself to pieces.  Princeton researcher Alicia Soderberg and her colleagues were lucky victims of happenstance.

On January 9th 2008 they were using a satellite called Swift to make routine measurements on a galaxy 88 million light years away called NGC 2770.  Suddenly, in the same cosmic neighbourhood, a bright flash of X-rays appeared for about 10 minutes, just where they happened to be looking. By feeding the coordinates of the flash into a host of telescopes including Hubble, some of Earth's most powerful eyes were quickly trained on the right patch of sky.  What unfolded next read like a chapter from a cosmologist's storybook. The team were able to watch as theoretical predictions and calculations were borne-out in real time.

What they were seeing was the death of a star, known as a supernova, from start to finish.  The first burst of X-rays occurred when the star, which was old and burned out, collapsed in on itself and then exploded. This created a huge shock-wave which tore outwards through the gas and debris shed from the surface of the star before its demise. This abrupt acceleration of particles in the gas to almost light speed by the explosion produces powerful bursts of X-rays, which is what the team first saw. The remaining stellar cinder becomes a very compact body called a neutron star.

The discovery, say the researchers, helps to confirm what physicists had long suspected but never been able to see. "For years we have dreamed of seeing a star just as it was exploding," says Soderberg. "We were in the right place at the right time and with the right telescope on 9th January and witnessed history."

25th May 2008