Astronomers Discover Secrets About Ancient Supernovae
In 2006 and 2007, astronomers associated with the Supernova Legacy Survey discovered two of the brightest supernovae ever seen. So big, in fact, that initially it wasn’t clear what they were or how far away they were at first.
SNLS-06D4eu“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 scientist D. Andrew Howell in a press release.
Howell is the lead author of a new study published in the Astrophysical Journal, where he and a team of researchers were finally able to uncover more about these two mysterious supernovae.
What they discovered is that these two supernovae exploded before our Sun was even born – they’re located 10 billion light years away. In fact, they’re a type of supernova that might not be able to form anymore – “a relic of an earlier form of supernovae that
is all but extinct today, ” the authors wrote in the paper.
The reason why they’re extinct is because the environments where they formed in early universe were a lot different from those in the universe as we know it today.
“These environments would have been common in the early universe, where the star formation rate was an order of magnitude higher than it is today, and the build-up of metals had not yet reached present-day levels, ” the researchers wrote in the paper.
According to the astronomers, these supernovae probably mark the creation of magnetars – neutron stars that spin incredibly fast. These magnetars have about the same mass of our own Sun, but they’re incredibly dense – only about the size of a city.
“What may have made this star special was an extremely rapid rotation, ” researcher Donald Kasen said in the 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.”
Superluminous supernovae like these two are pretty rare – comprising only about 1 in 10, 000 supernovae that astronomers normally observe. Now that scientists understand better how to measure their light and figure out where they’re located, though, scientists
can use this knowledge to learn more about them and about the early days of the universe.
“We hope to find many more of these kinds of supernovae with ongoing and future surveys, ” Howell said in the release.