Supernova explosion gets trapped by its own dust

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A giant star recently went supernova in a distant galaxy. Except you'd never know it, because the star emitted giant dust clouds that trapped and squelched the explosion. I don't believe stars can feel embarrassment...but yeah, that's pretty embarrassing.

Astronomers have never seen such an anticlimactic end to a supernova explosion, although they suspect this sort of thing happened more often in the early universe. A team at NASA's Spitzer Space Telescope were looking for black holes when they discovered a heat signature in a galaxy 3 billion light-years away that was unlike any they'd seen before. Whatever it was, the object burned incredibly hot and then disappeared in just a few months.


The fact that it flared out so quickly suggested it was a supernova, but those explosions are supposed to emit lots of light, not heat. And yet this object had reached temperatures of nearly 1,300 degrees Fahrenheit, so something was turning that light into heat. They soon realized the only possibility - the supernova must have gotten caught in a massive dust cloud that absorbed the light and spat out heat.

The astronomers have been able to work out the backstory of this object in remarkable detail. The star must have been about fifty times as massive as our Sun, as such stars are known to emit big clouds of material right before they explode. The first dust cloud was belched out some 300 years before it went supernova, and then the second cloud just four years before. The two then slowly expanded away from the star, creating a double-layered dust shell that trapped in all the light from the explosion.


The researchers believe these supernovas were much more common in the early universe, before galaxies had fused hydrogen and helium into heavier elements, and they are still occurring in smaller, low metallicity galaxies. In fact, the researchers say they now expect to find 100 or so of these in the next two years, now that they know what to look for. It hasn't exploded yet, but the astronomers suspect Eta Carinae, the brighest star system in the galaxy, could be similarly dust-smothered when it finally erupts.

The original dust-squelched supernova might still have a happy ending to its story, though. There's a chance the supernova will brighten considerably when the shockwave from the explosion hits the inner dust shell and sends it hurtling toward the outer shell. That could make for a spectacular light show.


[; click on the image up top for a closer look]