A Runaway Star Makes An Interstellar Bow Wave

By Kaila Hale-Stern on at

Zeta Ophiuchi zooms through interstellar space at 24 kilometres per second, pushing a bow wave of glowing gas and dust 12 miles wide in front of it.

The Spitzer space telescope created this false-colour infrared image of the runaway star and its bow wave. Zeta Ophiuchi is a young blue star about 19 times the mass of our Sun, and it’s about 366 light-years from Earth.

Astronomers believe that Zeta Ophiuchi was once part of a binary star system, but its partner exploded in a supernova. The cosmic divorce flung Zeta Ophiuchi out into interstellar space. Like all stars, Zeta Ophiuchi emits a constant flow of charged particles called solar wind, which compresses interstellar gas and dust into a sweeping curve ahead of the star. It’s the same way that fast-moving boats create bow waves in water, but on a cosmic scale.

As it races through space, Zeta Ophiuchi is also spinning rapidly; it rotates about once a day. That rapid rotation is probably also a side-effect of its violent ejection from its old binary system.