A classical nova is a spectacular stellar explosion that occurs every now and then in binary star systems where a white dwarf is burning through matter it sucks up from its sad-sack companion star. Scientists studied one such binary system for years, caught the lead-up to a nova explosion and its aftermath and released the spectacular images Wednesday. See some at the bottom of this article.
Astronomers started monitoring the binary star system V1213 Cen One using the Optical Gravitational Lensing Experiment (OGLE) in 2003. So they had witnessed six full years of build-up to a nova explosion they observed in 2009 now known as Nova Centauri 2009.
In the years before the big explosion, Przemek Mróz and colleagues at the Warsaw University Observatory saw evidence of some periods of brightening and smaller outbursts. The last such hiccup came within six days of the nova eruption, suggesting it "triggered a runaway thermonuclear reaction that led to the explosion," according to a release from the journal Nature, which published a summary of the observations Wednesday.
There's little hope of an encore explosion though, as it's believed such novae go back into a period of relative hibernation following a big blast. Follow-up observations seem to indicate that's the case. Sleep well, restless star.