In this paper, the distribution of four subclasses of four subclasses of SeyfertGalaxySeyfert 1s, Seyfert 1.
文章比较了四种赛弗特星系子类1型赛弗特星系，1。
2
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.