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Scientists Discover Biggest Star
Hugh Pickens writes "Scientists at the University of Sheffield have discovered the most massive stellar giant, R136a1 measured at 265 solar masses, using the European Southern Observatory's Very Large Telescope in Chile and data from the Hubble Space Telescope. It's in the Tarantula Nebula in the Large Magellanic Cloud, a small 'satellite' galaxy which orbits the Milky Way. Previously, the heaviest known stars were around 150 times the mass of the Sun, known as the 'Eddington Limit,' and this was believed to be close to the cosmic size limit because as stars get larger, the amount of energy created in their cores grows faster than the force of gravity which holds them together. 'Because of their proximity to the Eddington Limit they lose mass at a pretty high rate,' says Professor Paul Crowther, the chief researcher in the Sheffield team. Hyper-stars like R136a1 are believed to be formed from several young stars merging together, and are only found in the very heart of stellar clusters. R136a1 is believed to have a surface temperature of more than 40,000 degrees Celsius, and is 10 million times brighter than the Sun. Crowther adds that R136a1 is about as big as stars can get. 'Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon.'"
I'm guessing that what it probably means is that this star is estimated at having ten million times the power output compared to the Sun. Therefore, at some fixed reference distance, it would deliver ten million times more watts of illumination per square meter. This doesn't mean that the surface brightness is ten million times greater than that of the Sun, because some of the brightness comes from the greater size of the star. If you make a lamp with one hundred light bulbs, they are not individually brighter than a single light bulb, but as an aggregate, they provide more illumination, and can be more easily seen from farther away.