Fanaroff-Riley classification

The Fanaroff-Riley classification (FR classification) is a classification of radio sources intended to distinguish between active galactic nuclei (AGNs) versus radio galaxies:

• Class FR-I - luminosity decreases from a central point.
• Class FR-II - luminosity increases from a central point.

The first class appears to host an AGN, the second class represents a radio galaxy with lobes (regions away from the center emitting much of the radio electromagnetic radiation).