the bright star just below what is being called a shock-wave is I assume the remaining one of the suspected binary pair? ..... is the age of this system so great that there is no trace whatsoever of the other one? ... would you expect to see a sign (radial filaments showing the outward track of an exploding star?) and not to mention the seeming pristine condition of the survivor? .... it just looks so "clean" that its hard to imagine a possible destructive disintergration of its companion with so little trace of the event remaining ... it is only suggested a binary system may have been the reason for the shape of this "area"....What set this star in motion? Zeta Oph was likely once a member of a binary star system, its companion star was more massive and hence shorter lived. When the companion exploded as a supernova catastrophically losing mass, Zeta Oph was flung out of the system.
picture here ....... http://apod.nasa.gov/apod/ap110204.html