Most Massive Star Discovered: Over 300 Suns at Birth!

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Often, writing about astronomy tends to mirror the job of those writing for the Guinness Book of World Records – just when you think a record is practically unbeatable, somebody else appears to show up the previous record-holder. This is surely the case with the stellar heavyweight (er, “heavymass”) R 136a1, which has been shown by data taken using the European Southern Observatory’s Very Large Telescope and the Hubble Space Telescope to tip the stellar scales at 265 times the mass of our Sun. What’s even more impressive is that R 136a1 has lost mass over the course of its lifetime, and likely was about 320 solar masses at birth. That deserves a “Yikes!”

R 136a1 lies in a cluster of young, massive stars with hot surface temperatures that is located inside the Tarantula Nebula. The Tarantula Nebula is nested inside the Large Magellanic Cloud, one of the Milky Way’s closest galactic neighbors, 165,000 light-years away. The cluster is called RMC 136a (or more commonly referred to as R136), and in addition to the whopper that is R 136a1, there are three other stars with masses at birth in the 150 solar mass range.

Extremely massive stars like R 136a1 were previously thought to be unable to form, posing a challenge to stellar physicists as to just how this behemoth came about. It’s possible that it formed by itself in the relatively dense gas and dust of the R136 cluster, or that multiple smaller stars merged to create the larger star at some point early on in its lifetime.

If breaking the mass record weren’t enough, R136a1 also happens to be the most luminous star ever discovered, with an output of energy that is over 10 million times that of the Sun. If you want to learn more about how astronomers determine the mass and luminosity of stars, here is an excellent and thorough introduction to the subject.

To validate the models used in determining the mass and luminosity of the stars in R136, the team of astronomers led by Paul Crowther, Professor of Astrophysics at the University of Sheffield, used the VLT to examine NGC 3603, a closer stellar nursery. NGC 3603 is only 22,000 light years away, and two of the stars in that cluster are in a binary system, which allowed the team to measure their masses.

We are lucky to have observed this extremely massive star, as the rule for the most massive stars is, “Live fast, die young.” The more massive a star is, the faster it churns through the fuel that powers its increased luminosity. Our Sun, which has a medium amount of mass in relation to the two extremes, will last for around for about 10 billion years. Smaller, red dwarf stars can last trillions of years, while large stars on the scale of R 136a1 only glimmer in all of their brilliance for millions of years.

What will happen to R 136a1 at the end of its life? Stars with a mass of over 150 Suns ultimately explode in a light show of staggering proportions generated by what’s called a pair-instability supernova. For more on this phenomenon, check out this article from Universe Today from last year.

Source: ESO press release

A nod and a snarky wink to Genevieve Valentine