We love explosions, don’t we? Especially when they’re a) on TV or b) very far away from us. In this case, crazy far away, because I’m talking about supernovas — those spectacular events wherein a star dies and then has a cosmic funeral in the form of a massive explosion visible to the edge of the universe itself. Now astronomers have discovered a new variety of stellar explosion that’s…much smaller. It’s potentially even adorable. A kind of supernova that is so weak that the star itself survives it.
I daresay they take the “super” out of “supernova.” They’re so small that Ryan Foley, lead researcher at the Harvard-Smithsonian Center for Astrophysics, called it “essentially a mini-supernova. It’s the runt of the supernova litter.”
Supernovas are generally grouped into two classifications. Type Ia is where a white dwarf is destroyed because it stole too much mass from another star, and Type II occurs when a really big star runs out of fuel then collapses into a dense mass so quickly they just go haywire on a cosmic level.
This new, third classification came about because researches started to notice some Type Ias occurring but with significantly weaker blasts — 1% “peak luminosity” of the usual Type Ia. That’s when Foley and his colleagues looked closer and found 25 more examples of these mini-supernovas.
So what’s making them? They’re not entirely sure. Like the Type Ia, they come from binary star systems where there’s a white dwarf and a companion star. The data the researches have collected suggests that the helium in the companion star, bereft of its hydrogen shell, goes all nuclear fusion-like and blasts the white dwarf, making it erupt. Alternatively, the helium the white dwarf siphoned from its companion might alter the temperature and density of its interior, which in turn forces carbon, oxygen, and maybe the helium to start to fuse. Then BAM.
Whatever the cause, the blast is small in comparison to regular novas, and the white dwarf survives. It lingers on, wounded but purposeful, like Kate Winslet’s heart in Titanic or Arwen Undómiel’s life after the death of Aragorn.
Unsurprisingly, Foley explained it with different similes and metaphors:
“The star will be battered and bruised, but it might live to see another day. We’re not quite sure why only part of the star might get destroyed. That’s a tough problem we’re working on right now.”
“Type Iax supernovas aren’t rare, they’re just faint. For more than a thousand years, humans have been observing supernovas. This whole time, this new class has been hiding in the shadows.”
Supernovas…hiding in the shadows. I like that!
Space is silent and vast, but there are still a multitude of explosions going on that we’re clearly missing out on. And now we know — as Gary Larson of The Far Side knew — that some of them are little.
(via Space.com, images courtesy of Christine Pulliam)
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