Figure: The giant elliptical galaxy M87 at the heart of the Virgo
cluster of galaxies.
A galaxy classification in the Hubble scheme, ellipticals get their names from their overall shape. The ellipticals are subclassified by their degree of ellipticity as they appear to the observer. E0 types are completely spherical, and E7 types are very elliptical (i.e., elongated). E1 through E7 have increasing degrees of ellipticity. They are smooth and structureless, and contain mainly old Pop. II type stars. Ellipticals range in size from the relatively rare Giant Ellipticals, which can be as big as a Megaparsec across with a trillion stars, to the very common dwarf ellipticals which can be as small as a kiloparsec across with a million stars.
Figure: The giant elliptical galaxy M87 at the heart of the Virgo
cluster of galaxies.