Imagine a single star more luminous than a million suns, erupting every few decades in a massive flare that shines as bright as a supernova. But the blast, as ferocious as it is, does not obliterate the tumultuous star. It remains, its surface roiling with violence as spasms rock its inner layers. Soon enough the star will end its suffering in a final titanic blast, but before it does, it must suffer in this state for thousands of years.
This is a rare luminous blue variable star, and it may hold the keys to understanding the link between the lives of stars and their deaths.
Luminous blue variable (LBV) stars are indeed incredibly rare; astronomers have only identified about 20 (maybe) and suspect there are only a few hundred in the Milky Way, tops. Since they're so rare, they're poorly understood. And since they're so poorly understood, they're hard to characterize.