A half a century ago, the swan’s tail feathers got a little singed. A bright “new” star – a nova – flared into view close to Deneb, the star that represents the tail.
Known today as V1500 Cygni, it was one of the brightest novas ever seen. In a matter of hours, it grew about 40 million times brighter. It was visible to the unaided eye for several nights. And it took months to fade to its previous brightness.
V1500 is actually two stars. One of them is a heavy white dwarf – a hot, dense “corpse.” The other is a red dwarf – a small, cool, faint star that’s still in the prime of life.
The white dwarf is pulling gas from its feeble companion. Powerful magnetic fields funnel it onto the white dwarf. As the gas piles up on the white dwarf, the dead star’s gravity squeezes it into a thin layer, making the gas hotter and hotter.
In 1975, that layer got so hot that it exploded in a massive nuclear inferno. The blast disrupted the flow of material, and heated the surface of its companion – which is still cooling off.
Today, the white dwarf is stealing more gas from the companion. So it may flare up again in the centuries ahead – making things a bit uncomfortable for the tail of the swan.
Cygnus is high in the east at nightfall, anchored by Deneb. V1500 is close to the lower left of Deneb, but much too faint to see without a telescope – for now.
Script by Damond Benningfield