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The giant elliptical galaxy ESO 325-4. An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, [1] along with spiral and lenticular galaxies.
Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance. There are several schemes in use by which galaxies can be classified according to their morphologies, the most famous being the Hubble sequence , devised by Edwin Hubble and later expanded by Gérard de ...
M87's elliptical shape is maintained by the random orbital motions of its constituent stars, in contrast to the more orderly rotational motions found in a spiral galaxy such as the Milky Way. [67] Using the Very Large Telescope to study the motions of about 300 planetary nebulae, astronomers have determined that M87 absorbed a medium-sized star ...
NGC 3923 Elliptical Shell Galaxy (Hubble photograph) A shell galaxy is a type of elliptical galaxy where the stars in its halo are arranged in concentric shells. About one-tenth of elliptical galaxies have a shell-like structure, which has never been observed in spiral galaxies.
The lens in the structure of galaxies is an elliptical-shaped component with a nearly uniform distribution of surface brightness and sharp boundaries, whose contribution can be seen in the region between the bulge and the disk, and sometimes in other regions as well.
It is also important to consider the morphology of the galaxy when attempting to measure its size – an issue that has been raised by the Russian astrophysicist B.A. Vorontsov-Vel'Yaminov in 1961, which considers separate determination methods in measuring the sizes of spiral and elliptical galaxies. [2]
The type-cD galaxy [1] (also cD-type galaxy, [2] cD galaxy [3]) is a galaxy morphology classification, a subtype of type-D giant elliptical galaxy. Characterized by a large halo of stars, [4] they can be found near the centres of some rich galaxy clusters. [5] They are also known as supergiant ellipticals [6] or central dominant galaxies. [7]
At the centre of the Hubble tuning fork, where the two spiral-galaxy branches and the elliptical branch join, lies an intermediate class of galaxies known as lenticulars and given the symbol S0. These galaxies consist of a bright central bulge, similar in appearance to an elliptical galaxy, surrounded by an extended, disk-like