<Tr> <Td> </Td> <Td> This article includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this article by introducing more precise citations . (March 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile . Unlike flat spiral galaxies with organization and structure, they are more three - dimensional, without much structure, and their stars are in somewhat random orbits around the center . They are one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies . Elliptical galaxies range in shape from nearly spherical to highly flat and in size from tens of millions to over one hundred trillion stars . Originally Edwin Hubble hypothesized that elliptical galaxies evolved into spiral galaxies, which was later discovered to be false . Stars found inside of elliptical galaxies are on average much older than stars found in spiral galaxies . </P> <P> Most elliptical galaxies are composed of older, low - mass stars, with a sparse interstellar medium and minimal star formation activity, and they tend to be surrounded by large numbers of globular clusters . Elliptical galaxies are believed to make up approximately 10%--15% of galaxies in the Virgo Supercluster, and they are not the dominant type of galaxy in the universe overall . They are preferentially found close to the centers of galaxy clusters . Elliptical galaxies are (together with lenticular galaxies) also called "early - type" galaxies (ETG), due to their location in the Hubble sequence, and are found to be less common in the early Universe . </P> <P> Elliptical galaxies are characterized by several properties that make them distinct from other classes of galaxy . They are spherical or ovoid masses of stars, starved of star - making gases . The smallest known elliptical galaxy is about one - tenth the size of the Milky Way . The motion of stars in elliptical galaxies is predominantly radial, unlike the disks of spiral galaxies, which are dominated by rotation . Furthermore, there is very little interstellar matter (neither gas nor dust), which results in low rates of star formation, few open star clusters, and few young stars; rather elliptical galaxies are dominated by old stellar populations, giving them red colors . Large elliptical galaxies typically have an extensive system of globular clusters . </P>

What types of stars are found in elliptical galaxies