The galaxy before the supernova SN2008D and (above) the galaxy after SN2008D. Picture courtesy: Nasa/Swift Science Team/Stefan Immler

New Delhi, May 21: An international team of astronomers has for the first time spotted the birth of a supernova explosion — the beginning of the final, violent death throes of an obese star.

A network of space and ground telescopes helped capture the first moments of the death of a star in the galaxy NGC 2770, 90 million light years from Earth, the team announced today.

Astronomers have previously catalogued hundreds of supernova explosions, the end-stage events of massive stars, but never at the start.

“This is the first time anyone has seen a supernova so early while it’s starting out,” said Kim Page, a team member from the University of Leicester, UK. “The main X-ray signal, representing a shock breaking out at the start of the explosion, lasted 100 seconds and we were able to observe it.”

Supernova explosions typically occur only once or twice every 100 years. But when this explosion occurred on January 9, 2008, a team of astronomers was looking at another, older supernova in the same galaxy using Nasa’s orbiting Swift telescope.

“We were in the right place, at the right time, with the right telescope… and witnessed history,” said Alicia Soderberg, a research fellow at Princeton University. “We would have missed it if it weren't for the Swift’s real-time capabilities, wide field of view and numerous instruments,” she said.

Soderberg and her colleague Edo Berger alerted eight other telescope teams all of whom observed the supernova, named SN2008D, for several weeks, picking up its X-ray and other emissions.

The pattern of the X-ray outburst from the supernova is consistent with a shock wave bursting through the surface of a star, the team has said in a paper to appear in the journal Nature tomorrow.

A supernova occurs when the core of a massive star runs out of nuclear fuel and collapses under its own gravity to form a dense object known as a neutron star, which compresses and rebounds, triggering a shock wave that blows up the star.

“This discovery will be extremely useful for a better understanding of supernova physics,” said Kulinder Pal Singh, an astrophysicist at the Tata Institute of Fundamental Research, Mumbai, who was not part of the team. “It’s likely to help refine models of what happens during the initial shock wave,” Singh said.

He is a member of an Indian space science team that hopes to launch India’s Astrosat satellite next year that will be able to conduct follow-up observations on supernova explosions.

“We now know what X-ray pattern to look for. Hopefully, we will be able to find many more supernovae at this critical moment,” said Neil Gehrels, principal investigator with the Swift observatory.

Astronomers observed SN2008D using the orbiting Hubble Space Telescope, the Chandra X-ray Observatory, and ground telescopes in Hawaii, New Mexico and California — in addition to the first glimpses via Nasa’s Swift telescope.