A nearby white dwarf went supernova in 2011, giving scientists an unprecedented look at a rare Type Ia supernova. They discovered that it's remarkably, stunningly, perfectly 'normal.'
Supernova 2011fe was discovered just hours after it exploded in the Pinwheel Galaxy in the Big Dipper. Studies by the Nearby Supernova Factory of its spectrum as it evolved over time have produced a benchmark atlas of data by which to measure all future Type Ia supernovae.
B. J. Fulton / Las Cumbres Observatory Global Telescope Network
EnlargeAstronomers have weird names for things. Blame it on the fact that they started naming stars and planets a long, long time ago, back when they thought the sun went around the Earth. "Planet" means wanderer, even though planetary orbits are completely regular and predictable. A "planetary nebula" has nothing whatsoever to do with planets. And a Type II (aka Type 2, but astronomers insist on Roman numerals) supernova is common, but a Type Ia (1a) supernova is rare, with a bizarre origin story.?
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Rare, but useful. (We'll get to that.)
A group of astronomers just announced that they've found the perfect Type Ia supernova. The Platonic ideal of Type Ia supernovae: 2011fe.
What makes 2011fe so perfect? For one thing, the supernova spotters (known as the Nearby Supernova Factory) found it almost right away in August, 2011, when the supernova was less than 12 hours old.
?We?d never before seen a Type Ia supernova this early,? said Greg Aldering of the Lawrence Berkeley National Laboratory in a press release. For another, it's right in our galactic backyard ? just 21 million light years away ? so we got a crystal-clear view. Amateur astronomers could see it through binoculars.
Most of the Type Ia supernovae we've spotted before were far enough away that the light was distorted by interstellar dust. Astronomers can "correct" for those distortions, but in doing so, they have to make a lot of assumptions. That makes the data somewhat less trustworthy. This time, we got an undistorted view, giving us a gold standard against which to measure all future Type Ia supernovae. It's also "remarkably normal," the astronomers found ? the light curve fell right in the heart of normal distributions from past Type Ia observations, with no "peculiar" outliers to explain away.
Rollin Thomas, a member of the research team, remembers that as new data arrived from the telescope each night, he would think, ?Please don?t be peculiar, please don?t be peculiar.? His wish was granted: ?Our measurements showed how remarkably normal 2011fe is," says Dr. Aldering.
The researchers?began watching the supernova just hours after it began. Two weeks later, it reached its peak brightness, but they kept watching it, off and on, for another three months, as the light faded away. In the June (current) issue of Astronomy and Astrophysics, the Nearby Supernova Factory is releasing their 32 nights of data on 2011fe. They even made a movie of it.
Remind me: What's a supernova?
Nearly all supernovae are explosions caused by super-giant stars exploding. After a super-giant's core stops fusing, it begins to collapse on itself. As more and more mass falls inward, the atoms are forced to fuse together, resulting in a thermonuclear explosion. Think Nagasaki, but instead of something the size of a softball, it's a star 10 to 70 times bigger than our sun.
That's a Type II supernova.
But there are a few oddballs, known as Type Ia supernovae. Type Ias are also fusion explosions, but they're not caused by the sheer enormousness of the exploding star. In fact, Type Ia supernovae are kicked off by tiny white dwarfs.
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