The Dragon’s Eye – The Runaway Star Zeta Ophiuchi in Sh2-27

Here's a closeup of the magnitude 2.56 star Zeta Ophiuchi (ζ Oph) in the Sh2-27 nebula roughly 440 light years away. As I researched the Sh2-27 area, I became aware of this little gem—a runaway star speeding away from its point of origin at 54,000 miles an hour, thus creating a cool-looking bow shock as it ploughs through the gas and dust of Sh2-27.

ζ Oph is twenty times as massive as the sun, nine times its size, and an astonishing 80,000 times brighter. If not for the fact that Sh2-27's dust and gas surrounds it, this would be one of the two or three brightest stars in the sky. It's rotating once a day, which is almost enough to cause it to start coming apart. It would eventually leave the galaxy, but it will blow itself up in a Type II supernova long before that happens. Then who knows what will happen with the dead husk that is left behind (likely a neutron star)? The conjecture is that this star's tightly orbiting, more massive binary companion died in a Type II supernova explosion first. The ensuing loss of mass from the companion slung ζ Oph into the galaxy at large at high speed.

ζ Oph goes by the popular name Khan. It may refer to the bow shock rather than the star. I haven’t been able to nail that down. Perhaps this guy knows: