Probably a black hole in the center. As things are sucked into it, but before reaching the event horizon, stars are torn apart and dust/gasses are heated to intense temperatures. That is the bright glow. Once things pass the event horizon the gravity is so intense that even light cannot escape. The light outside of the event horizon is what looks like a star, but is very much larger than a star.
This video shows closeups of the Andromeda Galaxy that shows how small stars are on a galactic scale:
gigapixels of andromeda