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Stellar Whopper

March 22, 2016

Last June, the astronomers who study exploding stars caught a whopper: the most brilliant supernova yet seen. At its peak, it shined almost 600 billion times brighter than the Sun. And it’s taking some gaudy physics to explain it.

The supernova was inside a galaxy that’s 3.8 billion light-years away. The galaxy itself isn’t giving birth to many stars, so any supernova would be a rare occurrence.

But supernova ASASSN-15lh was unlike any ever seen in any galaxy. It was more than twice as powerful as the previous record holder, and hundreds of times brighter than a typical exploding star.

Astronomers are still trying to understand the cause of the blast. One possible explanation involves a magnetar — one of the most powerful magnets in the universe.

The idea says the explosion was triggered by the collapse of the star’s core to form an ultra-dense neutron star. The outer layers fell inward, then rebounded, blasting into space. The core’s implosion caused it to spin about a thousand times a second. That generated an extremely powerful magnetic field — perhaps a hundred trillion times more powerful than Earth’s — turning the neutron star into a magnetar.

That magnetic field created a powerful “wind” that slammed into the expanding cloud of debris from the explosion. That heated the debris and made it glow much brighter than a normal supernova — making ASSASSN-15lh the most luminous yet seen.

We’ll talk about something that’s even brighter tomorrow.

Script by Damond Benningfield

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