THE quickest supernova we have ever seen went from invisible to super bright in only 2.2 days. It is the first of these speedy stellar explosions that has been observed thoroughly enough to help us figure out exactly how they work.
Supernovae are massive explosions that happen when a star burns out. They usually take weeks or months after the death of the star to reach maximum brightness, and even longer to fade away. But at the Space Telescope Science Institute in Baltimore, Maryland, and his colleagues found one in data from the Kepler Space Telescope that rose to peak brightness in less than 53 hours and faded back to half that brightness in 6.8 days (Nature Astronomy, ).
Often, quick supernovae are dimmer than their longer-lasting counterparts, so they can be explained through a weaker mechanism, like a star that only partially exploded. But this one, called KSN 2015K, was just about as bright as a regular supernova, so the team thinks it may have started out dim and then received an extra boost.
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One possibility is that before the star went full supernova, it expelled a dying breath, releasing a dense shell of gas. When the star exploded within this shell about two months later, the initial explosion would have been invisible to us. But the debris that it spewed would quickly slam into the gas surrounding it and create a powerful shock wave. Then, the kinetic energy from the explosion would be converted into the blast of light that Kepler detected.
This article appeared in print under the headline 鈥淪uper-quick supernova peaks in just two days鈥�