A star system on the far side of the galaxy keeps blowing up. Since 1863, astronomers have recorded 12 outbursts from the system – the most recent just four years ago. The flare-ups are powered by a complicated interplay between a dead star and a companion that may be dying.
U Scorpii probably is more than 60,000 light-years away, far on the other side of the heart of the Milky Way Galaxy. Most of the time, the system is quite faint. But during the outbursts, it can flare 10,000 times brighter in just a few hours. It starts to fade quickly, but it takes about two months to return to its “quiet” state.
The system consists of two stars in a tight orbit. One of them is a white dwarf – the dead core of a Sun-like star. The other star is headed toward the same fate. It’s at the end of the prime phase of life, so it’s starting to puff up. The white dwarf “steals” some of the gas from its surface, forming a swirling disk.
Some of the gas piles up on the white dwarf. Eventually, the gas gets so hot, it sets off a nuclear blast, making the system flare up. The outburst blows away all or part of the disk. Before long, though, the process starts all over again – leading to another explosion a few years later.
U Scorpii is in Scorpius, which is low in the south-southeast at nightfall. The system is above the curving line of stars that outlines the scorpion’s body and tail.
Script by Damond Benningfield