But sometimes, like a misfiring firework, Type 1a supernovae sputter out before they reach peak luminosity. A new computer simulation model suggests that these failed supernovae contain multiple ignition points that expand the white dwarf too quickly and prevent full detonation of the star. Instead, there's an asymmetric explosion, something like a rocket jet. The kick of this explosion could, apparently, accelerate the white dwarf to speeds of hundreds of kilometres per second, enough to rip it out of orbit around its companion star, or even to turn it into a hypervelocity star travelling at a speed that would enable it to escape from the Milky Way. Imagine weaponising a supernova, turning a white dwarf into a bullet of electron-degenerate matter with the mass of the sun . . .
And if that isn't weird enough, it's not the only way that hypervelocity stars can be created. Stars orbiting close to the supermassive black hole at the centre of the Milky Way accelerate as they swing around it. Here's a neat simulation of the actual stars tracing their orbits:
If a multiple star system swings too close to the black hole, one of its members could gain enough momentum to escape its orbit, and zoom away at high speeds. When I wrote about this in Eternal Light, back in 1991, this was just a hypothesis. Since then, the Hubble telescope has spotted a massive hypervelocity star heading out from the galactic centre at some 2.6 million kilometres per hour, three times the sun's velocity as it traces its orbit around the galaxy. You really don't need to make it up . . .