Faster than a speeding bullet? More like faster than a supernova-propelled, hot blue supergiant!
In this stunning image fresh from NASA’s Wide-field Infrared Survey Explorer (WISE), a bright star can be seen in the center of the shot. This star is called Zeta Ophiuchi, located 458 light-years from Earth (and 20-times the mass of our sun) in the constellation of Ophiuchus (yes, that Ophiuchus).
Why is Zeta Ophiuchi so special? It’s a runaway star, traveling at a breakneck speed of 87,000 kilometers per hour (or 24 kilometers per second). And how did it get accelerated to that speed? After all, stars don’t just careen around the galaxy — eventually being ejected from the Milky Way all together — for no reason.
The massive Zeta Ophiuchi probably used to have an even larger binary partner that exploded as a supernova. So, like a hammer thrower spinning quickly at the Olympic Games, the blue supergiant star was treated like the hammer, released from the gravitational embrace of its exploding sibling in an instant. At the moment of detonation, it’s orbital momentum shot it off into space at high speed.
With the power of WISE’s infrared eyes, a consequence of the star blasting through interstellar dust and gas can be seen. The reddish arc folding around the star is a bow shock; strong stellar winds from Zeta Ophiuchi colliding with the interstellar medium, causing heating, thus infrared light WISE can see.
Seeing the position of the bow shock, you can easily deduce the direction the star is headed — toward the top-left of the image.
If there are any alien civilizations directly in the path of Zeta Ophiuchi, they’re in trouble, this stellar juggernaut isn’t slowing down any time soon.*
Image credit: NASA/JPL-Caltech/UCLA
* Although any nearby alien civilization might get lucky. As it’s a blue supergiant, it will likely explode as a supernova pretty soon in cosmic timescales. This “live fast, die young” star is estimated to be half-way through its 8 million year lifespan. We know how fast it’s traveling and we know (approximately) how long it’ll be until the star explodes, therefore, after a rough calculation, we can work how much further it will travel: another 317 light-years before it reaches the end of the road. Any alien civilization in the path of Zeta Ophiuchi will need to be at least 317 light-years from the star’s current position. Otherwise they’ll be toast.