Supernova PS1-10afx was discovered in 2010, giving off 30 times more energy than other events of its kind. The exploding star appeared to be emitting 100 billion times as much energy of the sun.
Type 1a supernovae are well-known to astronomers. They occur in binary star systems where at least one of the members is a white dwarf. This form of collapsed star has a mass about the same as the sun, compressed to the size of the Earth.
In systems were material is traveling from the larger companion to the white dwarf, this gas can build up around the super-dense body. When this accumulation reaches a critical threshold, it explodes in a Type 1a supernova. The brightness of the events is so consistent, they are used as a "standard candle" to measure the distance to far-away galaxies.
The tremendous energy given off by PS1-10afx led astronomers to question how so much energy could be released in the blast. Some believed they had witnessed a type of stellar explosion never before witnessed in the age of modern astronomy.
"PS1-10afx was different in just about every way. It evolved too fast, its host galaxy is too big, and it was way, way too red," Robert Quimby from the University of Tokyo said.
The astronomer believed the event was a normal Type 1a supernova, and our view was distorted by a massive object between the dying star and the Earth. Gravitation from this object could act like a magnifying glass, making the blast appear more powerful than actual energy released. The astronomer had one problem with his idea.
"We had no direct evidence for the lens. Thus each explanation required a bit of magic... and scientists don't generally buy into magic," Quimby said.
The astronomer used the Keck Telescope in Hawaii to observe the host galaxy of the expired star. He discovered another galaxy located between that collection of stars and the Milky Way. This hidden family of stars was discovered through measurements of gases in the telescope's field of view.
That tiny galaxy is old, mostly populated by dim, dying stars. When astronomers were studying the supernova, the lens galaxy was drowned out by the bright background. Gravitational lensing from the ancient galaxy created several images of the "normal" supernova taking place in a background galaxy.
"It is in the constellation of Aquarius, but you'll need a really big telescope to catch a glimpse," Quimby told reporters at a press conference held at the University of Tokyo.
The odd nature of the PS1-10afx measurements was detailed in the journal Science.
