Massive stars can be their own worst enemy, especially when they get old. A new Hubble Space Telescope observation focuses on such a star that is about self destruct as a blazing supernova.
[SBW2007] 1 (or SBW1) is located 20,000 light-years from Earth and features an enigmatic double-ringed planetary nebula. The rings are gases that have been blasted from the outermost layers of the blue supergiant star in the nebula’s core. The star, which was estimated to be 20 times the mass of the sun before it became unstable, is going through its final death throes before a supernova is initiated. But don’t worry, the supernova would be a safe distance from us, although it will put on an exciting light show.
Massive stars like SBW1 live fast and die young. Blue supergiants burn through their supply of hydrogen quickly in their cores where fusion processes take place. In only a few million years they run out of hydrogen and are forced to burn through heavier and heavier elements until they begin to bloat and powerful stellar winds shed their outer layers to form a nebula. At that stage, the stage is set for one of the biggest explosions known to occur in the Cosmos.
But how do we know SBW1 is about to blow?
This new Hubble observation isn’t without precedent. In 1987, another star with a strikingly similar nebula detonated as a supernova — the famous SN 1987A. From the shape and size of that star’s nebulous rings, astronomers knew that the gases were likely stripped from the star 20,000 years earlier. Using the knowledge they accumulated about SN 1987A, astronomers believe that SBW1 is also likely to go supernova as its rings are also approximately 20,000 years old. The nebula rings are analogous to a fuse on a bomb — it’s giving us an approximate idea about how long the star’s self destruct timer has been set.
Although it is tempting to say that SBW1 will explode “any day now,” that “day” is measured in cosmic time scales, which could mean tomorrow or a thousand years from now. Still, this dying star will remain the focus for fascinated astronomers for some time to come, just in case its timer does tick to zero.