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R136a1 - The Most Massive Star Known
What is a star?
You most likely already know what a star is. We see one every day, unless you're nocturnal or live in the Arctic. The Sun is our Solar System's star and it accounts for 99.85% of all the mass within it, so it's pretty large. In fact, it would take 1.3 millions Earths to fill up the Sun, a rather scary figure. Taking all this information into account, it's rather mind blowing to realise that there are stars that are far bigger than our Sun. There are millions, billions maybe, in our galaxy alone, and who knows about other galaxies out there that are undiscovered and unexplored. The heaviest we know of to this date is lovingly named R136a1 - a hard name to remember. It's called this because it belongs to the R136 Super Star Cluster in the Tarantula Nebula and the 'a1' just identifies which star it is in the cluster.
Facts about the star
- It is a 'Wolf-Rayet' star. This means it's losing mass rapidly due to a very strong stellar wind. They are very hot stars with temperatures of aroun 30,000-200,000 Kelvin, and are also highly luminous, several million times the luminosity of the Sun.
- It is the most massive star known to man, not the largest in volume. This title is owned by NML Cygni, a red hypergiant.
- It's luminosity is 8,700,000 times that of the Sun.
- It is an estimated 265 solar masses. (265 times the mass of the sun)
- It's surface temperature is over 50,000 Kelvin.
Comparing other stars to R136a1
The first news of the discovery of R136a1 was in July 2010 when a British team of astronomers used data from the Hubble Space Telescope to study the Star Cluster R136a1 is in. They also studied another star cluster, NGC 3603, situated around 20,000 light years from the Solar System. The team also found several other stars in the cluster with surface temperatures exceeding 40,000 Kelvin, which is more than 7 times that of the sun, and several million times brighter. 3 of the stars were massive, weighing over 150 solar masses.
It was also discovered and estimated that the star is rapidly losing solar masses, and would have weighed over 320 at its birth. It has lost over 50 in the past million years. Stars such as this will end their lives with a hypernova, a super massive supernova explosion with an energy level of over 1046 joules.
Comparing R136a1 to the Sun and the Earth
This really makes us realise how small and insignificant we actually are. R136a1 is so large that it makes the Sun appear tiny, just like the way that the Sun dwarfs the Earth in comparison. If there was a photographic comparison of the Earth and R136a1, the Earth would be a mere pixel, or maybe even invisible as seen in the video.
I hope this Hub has interested you and that you have learnt something about R136a1. Stars are fascinating masses and I hope to be writing about more of them. If you liked this post feel free to check out some of my other Hubs.
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