Nova GK Persei is a white dwarf star that threw an epic fit. It steals material from its companion star, and this material piles up on its surface, heated and hugely compressed. All at once it underwent catastrophic nuclear fusion, detonating like a bomb, blasting countless trillions of tons of matter outward at 1000 km/sec.
That happened more than 1,400 years ago. The light reached Earth in 1901, and over the ensuing century we have watched the debris expand like fireworks.
(thanks Miss Rare)