Scientists find 'monster' star, largest ever discovered

A team of scientists say they have found the heaviest star ever discovered, hundreds of times more massive than the Earth's sun.

The star, elegantly called R136a1, may have once weighed as much as 320 solar masses – twice as heavy as any other star discovered.

It's burning so strongly that it shines with nearly 10 million times the luminosity of the sun – comparable to the difference in brightness between the sun, and the Earth's moon.

Astrophysicist Paul Crowther of University of Sheffield in northern England, says R136a1 has slimmed down considerably.

"Unlike humans, these stars are born heavy and lose weight as they age. 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 fifty solar masses," he said in a news release.

"Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon."

The giant star was found at the centre of a star cluster in the Tarantula Nebula, within the Large Magellanic Cloud, a neighbouring galaxy to the Milky Way.

R136a1 was one of a number of massive stars discovered by Crowther and his team as chronicled in an article in the Monthly Notices of the Royal Astronomical Society.

The mass of R136a1 and other giants means they are brighter and hotter than our sun.

Surface temperatures can reach 40,000 degrees Celsuis, seven times hotter than the sun. That also means the giants stars burn through their energy reserves far faster than smaller ones, shortening their lives considerably.

Crowther said the giants only have a life expectancy of about three million years before burning out. Their short lifespan makes it more difficult for astronomers to figure out their origins.

"Either they were born so big or smaller stars merged together to produce them," he said.

The team acknowledged that it is possible that two very close stars had been confused for a single bigger one in the case of R136a1. However, they said the second star would have to be much smaller, and the bigger star would still be close to 300 solar masses.

The discovery was made by using archival data from the Hubble Space Telescope and new readings from the European Southern Observatory's Very Large Telescope at Paranal in Chile.