About the image. Drawn as a blinding blue-white star inside a crowded cluster of young stars and glowing nebula. From Earth even large telescopes struggle to separate R136a1 from its neighbours; its surface and the arrangement of the cluster are imagined.
The Tarantula Nebula, in our neighbouring galaxy the Large Magellanic Cloud, is one of the most active star-forming regions in our part of the universe. At its heart is a dense, young cluster called R136, and in the middle of that cluster is R136a1, the most massive star ever found.
A record that keeps moving
In 2010 a team led by Paul Crowther announced, using the Very Large Telescope and Hubble, that R136a1 had a mass of about 265 Suns, and perhaps 320 when it was born. That was well above the 150 solar masses many astronomers had thought was the upper limit for a star.
Later studies have revised the number up and down: 315 Suns in 2016, 251 in 2020, and in 2022 Venu Kalari and colleagues, using sharper images from the Gemini South telescope, found it closer to 200. The difficulty is that R136 is so crowded that light from neighbouring stars blends with R136a1’s; when they are separated, it appears fainter, and so lighter. Even at the lower figure it is the heaviest star known.
Extreme in every way
R136a1 is only about a million years old. Its surface is about 46 000 K (45 730 °C), eight times as hot as the Sun’s, and it shines several million times more brightly. It is not especially large, only about 43 times the Sun’s width, because it is so hot and dense. It is so luminous that the pressure of its own light pushes its outer layers away in a powerful wind, at about 2 600 kilometres per second, carrying off roughly an Earth’s worth of mass every week.
A short life
Stars this heavy live fast and die young. R136a1 will probably end its life as a supernova, very likely leaving behind a black hole. It is so far away that we will never be in any danger from it.
To scale · radius, Sun = 1Sun: 1.00 · R136a1: 42.7
How hot is it?
Earth (average)288 K · 15 °C
Water boils373 K · 100 °C
Venus surface737 K · 464 °C
Iron melts1 811 K · 1 540 °C
Sun's surface5 772 K · 5 500 °C
R136a146 000 K · 45 730 °C
R136a1: surface temperature. Logarithmic scale from 100 K to 10 000 K. Reference values: NASA, IAU.
Gallery
A dense cluster of blue-white stars with one blazing at its centre, inside a swirling pink and violet nebula, an impression of the R136 cluster and its star R136a1. AI-generated painting.A huge, blinding blue-white star with a churning surface, with smaller blue stars glowing nearby, an impression of R136a1. AI-generated painting.R136a1, 3D artist's impression, rendered from the interactive model.R136a1, 3D artist's impression, from another angle, rendered from the interactive model.R136a1, 3D artist's impression, close-up, rendered from the interactive model.
Timeline
1985R136a is resolved into separate stars.
2010Paul Crowther's team announces a mass of about 265 Suns.
2022Gemini South speckle imaging lowers the estimate to about 200 Suns.
Questions people ask
What is the most massive star?
R136a1, with an estimated 200–300 times the Sun's mass.
Is R136a1 the biggest star?
No. It is the heaviest, but only about 43 times the Sun's width. Red supergiants are far larger but much lighter.
How far away is R136a1?
About 163 000 light-years, in the Large Magellanic Cloud.