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Astronomers Saw a Star Explode from Multiple Angles, and Expect It to Echo

“You couldn't have designed a better experiment."
March 5, 2015, 7:30pm
​Enhanced image of the supernova. Credit: NASA/ESA/GLASS/ FrontierSN team

​For the first time ever, astronomers have captured an image of a supernova through the universe's most powerful telescopic lens: gravity. Thanks to an effect known as gravitational lensing, massive celestial bodies can distort light emitted by the objects behind them. From our perspective on Earth, these objects appear to be much larger due to this optical wormhole.

Astronomers have been exploiting​ gravitational lenses to study distant objects for years. But until now, nobody has captured an exploding star.

"The supernova appears 20 times brighter than its normal brightness," said cosmologist Jens Hjorth in a sta​tement.

The image of the supernova was also multiplied four times in a cross-like pattern, which is another effect of the gravitational light distortion. This phenomena is known as an Einstein cross, because of its relativistic spacetime trappings.

The cross-like pattern is visible around the 2014 image. Credit: NASA/ESA/GLASS/ FrontierSN team

The details of the discovery are collected in a new s​tudy in Science, but needless to say, it represents an extremely lucky break for astronomers. For starters, the images are especially spectacular due to the combination of two different lensing effects.

"The massive galaxy cluster focuses the light from the supernova and produces at least three different images," said Hjorth. "One of these images' light paths then happens to intersect with a large elliptical galaxy in the cluster of galaxies and this causes a second lensing effect that we see as the four images configured into an Einstein cross."

But beyond the novelty of capturing close-ups of a supernova nine billion light years distant, the find has repercussions for studying dark matter.

This is where it gets truly mind-boggling. Astronomers expect the light from this supernova to be bounced around many different ways as it navigates through the cluster. This means that the star's explosive death could repeatedly appear in different permutations over the coming years, due to an optical ricochet effect. By studying the different properties of these ghostly projections, astronomers can map the distribution of the cluster's dark matter web.

The repeating nature of the supernova, illustrated. Credit: NASA/ESA/GLASS/ FrontierSN team

"It's perfectly set up, you couldn't have designed a better experiment," said astronomer Brad Tucker, a co-author on the Science paper, in a s​tatement. "You can test some of the biggest questions about Einstein's theory of relativity all at once—it kills three birds with one stone."

It's a mere century after Albert Einstein first introduced the concept of gravitational lensing, and astronomers have already used it to zoom in on the ancient, photonic swan song of a long dead star. Not only that, but we're expected to catch some data-rich reruns of this death scene in the near future. When it comes to locking down the trippiest news stories, the cosmologists win again.