Astronomers Discover Two of the Most Ancient and Brightest Supernovae Ever Recorded

Astronomers have made an astonishing discovery. They've found two of the brightest and most distant supernovae ever recorded. Located about 10 billion light-years away, these powerful, ancient explosions are about a hundred times more luminous than normal supernovae.

The newly discovered supernovae are somewhat puzzling. The mechanisms that power most supernovae, such as the collapse of a giant star to a black hole or normal neutron star, can't explain the extreme luminosity of the ones recently seen by astronomers. In fact, they're so unusual that at first, astronomers couldn't figure out exactly how far they were from Earth.

"At first, we had no idea what these things were, even whether they were supernovae or whether they were in our galaxy or a distant one," said Andrew Howell, one of the researchers, in a news release. "I showed the observations at a conference, and everyone was baffled. Nobody guessed they were distant supernovae because it would have made the energies mind-bogglingly large. We thought it was impossible."

So what exactly are these supernovae powered by? Most likely, they're energized by the creation of a magnetar, an extraordinarily magnetized neutron star spinning hundreds of times per second. Magnetars have the mass of the sun packed into a star the size of a city and have magnetic fields a hundred trillion times that of Earth.

In fact, one of the newly discovered supernovae, named SNLS-06D4eu, is what is known as a superluminous supernovae. Yet what makes these supernovae so interesting is that they belong to a special subclass of superluminous supernovae that have no hydrogen.

In order to get a better glimpse of this superluminous supernova, the researchers actually matched detailed observations to models of what such an explosion might look like. These models explained the data as the explosion of a star only a few times the size of the sun and rich in carbon and oxygen. The star was likely initially much bigger but apparently shed its outer layers long before exploding. This left behind only a smallish, naked core.

"What may have made this star special was an extremely rapid rotation," said Daniel Kasen, one of the researchers, in a news release. "When it ultimately died, the collapsing core could have spun up a magnetar like a giant top. That enormous spin energy would then be unleashed in a magnetic fury."

The findings are published in the Astrophysical Journal.