An amateur astronomer has made a major discovery by recording the violent death of one of the most massive stars in the universe. An international team, led by astronomers at Queen’s University, Belfast, have now identified the suicide star.

Japanese amateur astronomer Koichi Itagaki first photographed a star exploding in a faint galaxy called UGC 4904 in 2004. Two years later he recorded a second, even greater explosion in the same spot, 78 million light years away in the constellation of Lynx.

The double blast excited professional astronomers because they believe Koichi witnessed the death of one of the “heaviest” stars that can exist.

Last month, we reported how a similar supernova had produced the brightest explosion ever witnessed in another galaxy.

Professor Stephen Smartt, of Belfast, and colleague Dr Andrea Pastorello heard of Itagaki’s photographs and immediately realised the implications of spotting two explosions in the same place in the sky.

They began observing the supernova, named SN2006jc, with telescopes on La Palma in the Canary Islands. They also analysed Itagaki’s photos and confirmed that one star exploded twice. They say it must have been a so-called Wolf-Rayet star, which are the most massive type known.

Dr Pastorello said: “We knew the 2004 explosion could be a giant outburst of very massive star, and we know that only the most massive stars can produce this type of outburst. So the 2006 supernova must have been the death of the same star, possibly a star 50 to 100 times more massive than the Sun.”

A similar star in our own galaxy, called Eta Carinae, exploded in the 1850s. Astronomers say it could blow itself to pieces at any time, producing one of the brightest explosions ever seen in the sky and becoming visible in daylight.

Picture: An artist’s impression of the 2006 blast by Frederic Durillon. Courtesy Service d’Astrophysique/CEA.

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