The most massive star ever, which is up to 20 million times brighter than the Sun, has been discovered using the Very Large Telescope in Chile, scientists in Britain said Wednesday.
The star, named R136a1, is thought to have started off with a mass of up to 320 times that of the Sun and the new discovery has doubled the previously accepted limit of solar mass.
Although it has since shed some of its weight, it is so powerful that if it replaced the Sun as the centre of our solar system, it would make life on Earth impossible because of the strength of its ultraviolet radiation.
R136a1 was discovered as part of a series of massive stars found in two young star clusters by a team of astronomers led by Professor Paul Crowther of Sheffield University in northern England.
"Unlike humans, these stars are born heavy and lose weight as they age," Crowther said.
"Being a little over a million years old, the most extreme star R136a1 is already middle-aged and has undergone an intense weight loss programme, shedding a fifth of its initial mass over that time, or more than 50 solar masses.
"Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon."
Crowther added that astronomers faced a challenge to work out how the stars originated.
"Either they were born so big or smaller stars merged together to produce them," he said.
The Very Large Telescope project, in the Atacama Desert in northern Chile, is operated by the European Southern Observatory (ESO).
It features four eight-metre diameter telescopes and is described by the ESO as "the world's biggest eye on the sky".
Researchers studied the stars using it plus data from the NASA/European Space Agency's Hubble Space Telescope.
The research, conducted by scientists from Britain, Malaysia and Germany, was published in scientific journal The Monthly Notices of the Royal Astronomical Society.
When stars between 8 and 150 solar masses die, they usually go as big supernovae explosions, collapsing into black holes or neutrons stars. However, some researchers believe that stars between 150-300 solar masses could explode without leaving behind a trace, in so-called ’pair-instability' supernovae. As such a supermassive star ages, its photons would start converting into electrons and positrons (so-called ’pair production), which would decrease the outward pressure on the star. It is this decrease in pressure that would make the giant collapse and finally explode.
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