A space telescope has spotted the brightest exploding star ever seen in the universe. The supernova occurred in a distant galaxy but astronomers say a star in our own Milky Way could be lining itself up for a similar stellar suicide.
When a star destroys itself in a monumental explosion, it briefly becomes as bright as all the thousands of millions of stars in one galaxy combined.
The blast recorded by Nasa’s Chandra X-ray Observatory and other telescopes was a hundred times more brilliant than normal. That leads scientists to believe that they may have detected a new type of supernova that they had long been seeking.
Astronomer Alex Filippenko, who led ground-based observations from Lick Observatory, California, and the Keck Observatory on Hawaii, said: “Of all exploding stars ever observed, this was the king. We were astonished to see how bright it got, and how long it lasted.”
The wrecked star was probably as massive as it could be, at around 150 times the “size” of our own Sun. Astronomers say such violent explosions may have been fairly common in the early universe when a first generation of extremely massive stars existed.
The suicide victim has been labelled SN 2006gy and lies 240 million light-years away in the galaxy NGC 1260 in the constellation of Perseus. Astronomers say the star gave an early warning of its demise by expelling a large cloud of material before the explosion itself was spotted on September 18 last year.
This loss of mass is similar to matter seen ejected from Eta Carinae, a massive star lying just 7,500 light-years away in our own galaxy. Mario Livio of the Space Telescope Science Institute in Baltimore, commented: “We don’t know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case. Eta Carinae’s explosion could be the best star-show in the history of modern civilization.”
Eta’s distance means, of course, that it could have gone bang already and we just don’t know about it yet! An explosion would turn night into day in the southern hemisphere but go unseen from much of the northern hemisphere, such as London or New York, from where the star never rises.
The supernova that appeared the brightest in recent history was SN 1987A, seen in 1987, which was only bright because it erupted in a satellite galaxy of our own Milky Way. Ten years later, it had left a stunning ring of pearls.
A report on supernova SN 2006gy is to appear in the Astrophysical Journal.
Photo: Astronomers from the University of California, Berkeley, took this infrared image showing SN 2006gy (right) and the nucleus of its host galaxy, NGC 1260. (Lick/UC Berkeley/J. Bloom & C. Hansen).