Say hello to NGC 6946, otherwise known as the Fireworks Galaxy. This little galaxy is the most prolific producer of supernovae in the known universe, popping off those incredible explosions roughly once a decade. It’s secret? An incredibly high rate of star formation.
NGC 6946 sits about 25 million light-years away, close enough that it was once thought that it was a part of the Local Group, our galactic neighborhood in the universe. It’s not that big of a galaxy – roughly 40,000 lightyears across – but what it lacks in size it makes up for in panache.
Over the past 100 years, astronomers have witness ten supernovae explosions in the Fireworks Galaxy, as NGC 6946 is better known. That’s much higher than your average spiral galaxy, which typically only produces a few every century. What’s more, X-ray observations have revealed even more supernovae in the recent past, indicating that this is not a new thing for NGC 6946.
Ironically, the boastful supernovae rate in NGC 6946 isn’t because the Fireworks Galaxy is good at killing stars, it’s because it’s good at making them. NGC 6946 has a higher-than-average star formation rate. More stars of all kinds = more big, short-lived stars = more supernova explosions.
So why does NGC 6946 have such a high star formation rate? Astronomers aren’t sure. Perhaps it suffered a recent merger. Or perhaps its gas reserves cooled and contracted all at once. While we puzzle over this particular astronomical riddle, at least we can enjoy the show.