The radio galaxy and quasar story became clearer with the discovery of another class of galaxy that exhibit violence in their cores and which are relatively faint radio sources. The best known of these is a variety of spirals called Seyfert galaxies that show broad optical emission lines at their cores, the broadness indicating extremely chaotic, violent movement at the centers of those galaxies, motions which are not found in the more peaceful and normal spiral galaxies such as our own. Many Seyferts also show peculiar and distorted appearances on optical photographs. An example of a radio source centered on a Seyfert galaxy is shown in Figure 12.2. Their radio emission is usually confined to the core region and if a jet is present it is usually very short, less than a thousand light-years long because it cannot penetrate the surrounding gas and dust in the core of the spiral galaxy. Seyfert galaxies represent a class of objects that are neither a radio galaxy nor a quasar yet they exhibit chaotic motion in their cores.
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