The University of California-Santa Barbara reports that the “dinosaurs of supernovae” have been found: two of the brightest, most distant supernovae ever recorded have been detected by astronomers. These supernovae are 100 times brighter than your run-of-the-mill supernovae.

According to Caltech, supernovae are exploding stars. They represent the very last stages of development for some stars. They are large releases of tremendous energy, as the star ceases to exist, with approximately 10²⁰ times as much energy generated in the supernova explosion as our Sun releases every second.

We know that supernovae have taken place in our Milky Way galaxy in the past, because both Tycho Brahe and Johannes Kepler found luminous supernovae occurring in our galaxy in 1572 and 1604, respectively.

The supernovae in question were so unusual that astronomers couldn’t initially determine what they were or how far away they were located. However, astronomers believe that one of the newly found supernovae is the most distant and likely the brightest member of the emerging superluminous supernovae class. These new findings below to a unique subclass of superluminous supernovae that contain no hydrogen.

“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,” noted D. Andrew Howell, adjunct faculty at UC Santa Barbara, in a statement. “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.”

The study reveals that the supernovae are probably powered by the formation of a magnetar, an extremely magnetized neutron star rotating hundreds of times per second.

“What may have made this star special was an extremely rapid rotation,” remarked Daniel Kasen from UC Berkeley and Lawrence Berkeley National Lab. “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.”

Although the two supernovae could not initially be identified nor could their distances from Earth be measured, new observations of the faint host galaxy with the Very Large Telescope aided astronomers with the calculations of the distances and energy of the explosions.

The supernovae are so distant that the UV light emitted in the explosion was stretched out by the expansion of the universe until it was redshifted into the part of the spectrum Earth-based telescopes can observe.

According to astronomers, the supernovae exploded when the universe was only 4 billion years old.

“This happened before the sun even existed,” Howell posited. “There was another star here that died and whose gas cloud formed the sun and Earth. Life evolved, the dinosaurs evolved and humans evolved and invented telescopes, which we were lucky to be pointing in the right place when the photons hit Earth after their 10-billion-year journey.”

“These are the dinosaurs of supernovae,” Howell concluded. “They are all but extinct today, but they were more common in the early universe.

These particular supernovae are very rare, occurring once for every 10,000 run-of-the-mill supernovae. In fact, they seem to explode primarily in older galaxies.

For more information check out the authors’ detailed write up in the Astrophysical Journal.