Hubble sequence
In the modified Hubble sequence galaxy morphological classification scheme of the French astronomer Gérard de Vaucouleurs, M87 is categorized as an E0p galaxy. "E0" designates an elliptical galaxy that displays no flattening—that is, it appears spherical. A "p" suffix indicates a peculiar galaxy that does not fit cleanly into the classification scheme; in this case, the peculiarity is the presence of the jet emerging from the core. In the Yerkes (Morgan) scheme, M87 is classified as a type-cD galaxy. A D galaxy has an elliptical-like nucleus surrounded by an extensive, dustless, diffuse envelope. A D type supergiant is called a cD galaxy.