Wow a few stars in that image too Dougie
nice job
A couple of things to watch though:
1) Careful with the blending of the inner and outer core areas, it can look pretty obvious if you aren't careful
2) Watch the use of shadow highlights as it can flatten the image, Omega is a 3D ball not a flat circle, in fact it is an almost oblate football shape really and the flattening caused by the shadow highlights can mask this. The centre needs to be brighter than the edges to give it some sort of ball like appearence.
Still a cool image
Mike