What is the 'monster star'?

Astronomers have discovered the largest known star in the universe. It's 10 million times brighter than our sun, and seven times hotter. At least one commentator wants to call it "Heath Ledger"

Scientists have discovered the largest known star in the universe. Officially it's known as R136a1 — but less formal types have dubbed it the "monster star." (Watch a report about the "monster star.") Here's an instant guide to the star is so bright, it "outshines the sun as much as the sun outshines the moon":

How big is it?

It is by far the biggest star yet discovered by astronomers. Its mass is roughly 265 times greater than that of our sun, and used to be larger — around 320 times greater — when it was "born." The "monster star" shines 10 million times brighter than the sun, and its surface temperature — 40,000 degrees celsius — is seven times hotter.

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How old is it?

The star is thought to be about 1 million years old, making it a relative toddler compared to our own sun which is about 4.5 billion years old. But so-called "hypergiants" burn out far more quickly, meaning it is only likely to exist for another million years before going supernova.

Where is it?

It's in the Large Magellanic Cloud, a smallish galaxy very nearby (in astronomical terms) the Milky Way. The star makes up part of the Tarantula Nebula, and is one of several "hypergiants" to be discovered there.

How does such a large star come to exist?

Good question. It's "hard to explain" how these hypergiants come to accumulate so much mass in a comparatively short space of time, says Pete Spotts at The Christian Science Monitor. That's one of the reasons why some scientists think R136a1 is actually a cluster of bunched-together stars, too close for our most powerful telescope to differentiate.

Can I see it in the night sky?

Unfortunately not. Astronomers used an instrument creatively titled a Very Large Telescope to view the star from an observatory in Chile. The Large Magellanic Cloud, however, is visible as a faint smudge to stargazers in the southern hemisphere.

How significant is this discovery?

It's not a big breakthrough, says Martin Rees, a British astronomer, quoted in The Guardian. We've seen stars like this before, just not as big. "It's a step forward, but it is not more than an incremental advance in our knowledge." That said, says astrophysicist Scott Kenyon in The Christian Science Monitor, it could give us a "better grasp" of how such massive stars come to exist.

Couldn't we give it a better name?

Agreed. R136a1 sounds like an "obscure insurance form," says Tom Meltzer at The Guardian. "A more impressive one seems essential." What about an homage to other stars who burned bright but briefly: "Heath Ledger? Bill Hicks?"

Sources: CNN, Christian Science Monitor, The Guardian

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