Three cosmic explosions could precede supernovae

5.00pm

A trio of powerful explosions emanating from three different regions in space could mean astronomers might see stars blowing up within days, scientists said today.

Astronomers believe the blasts - which took place on September 12, 16 and 24 and lasted only a few seconds each - may be precursors to stellar explosions called supernovae. If this turns out to be true, astronomers would have a new tool to predict these explosions, and researchers could watch the blasts from start to finish.

The first two space explosions were X-ray flashes, while the third was a more powerful blast called a gamma ray burst, the scientists said in a statement.

The explosions occurred in the constellations Aquarius, Pisces and Aries, and all are more than 1 billion light-years from Earth, and also far away from each other, said George Ricker of the Massachusetts Institute of Technology, whose team detected the explosions with NASA's High-Energy Transient Explorer (HETE-2) satellite.

The two in Aquarius and Pisces were the less powerful X-ray flashes, and may range from 1 billion to 3 billion light-years' distance from Earth, Ricker said in a telephone interview. The gamma ray burst was located in Aries could range from 1 billion to 8 billion light-years distance, he said.

A light-year is about 10 trillion kilometres, the distance light travels in a year.

Theoretically, within 10 to 20 days of these blasts, observers might see supernovae in these three locations, Ricker said.

"Astronomers now have three places that they can look ... If they're looking at the right spot at the right time, they'll see a supernova turn on, and that would be the first time that's happened for an X-ray flash," Ricker said. It happened last year for a gamma ray burst, he said.

Gamma ray bursts are the most powerful explosions known other than the theoretical Big Bang that many astronomers believe gave birth to the universe. Previous research with the same HETE-2 satellite showed a connection between gamma ray bursts and supernovae.

The lower-energy X-ray flashes might be gamma ray bursts viewed slightly off-angle, somewhat similar to how a flashlight is less blinding when viewed at an angle.

These three recent blasts could help determine whether X-ray flashes, like gamma ray bursts, are related to supernovae. If they are, that would be good news for scientists who study exploding stars: X-ray flashes are somewhat closer to Earth than gamma ray bursts and the supernovae could be easier to observe.

- REUTERS