Caption: a face-on snapshot of the small spiral galaxy NGC 7742, not just any old spiral galaxy but a Seyfert 2 - a galaxy that is probably powered by a black hole at its core.

This particular galaxy is described as Seyfert 1 galaxy, which typically have bright centres emitting a broad range of hydrogen emission but narrow emission lines of heavier elements such as iron.

In this paper, the distribution of four subclasses of four subclasses of Seyfert Galaxy Seyfert 1s, Seyfert 1.