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An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four 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. Elliptical (E) galaxies are, together ...
Types of galaxies according to the Hubble classification scheme : an E indicates a type of elliptical galaxy; an S is a spiral; and SB is a barred spiral galaxy. Galaxies come in three main types: ellipticals, spirals, and irregulars. A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence.
Elliptical and lenticular galaxies are commonly referred to together as "early-type" galaxies, while spirals and irregular galaxies are referred to as "late types". This nomenclature is the source of the common, [18] but erroneous, belief that the Hubble sequence was intended to reflect a supposed evolutionary sequence, from elliptical galaxies ...
A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. [1] It contains a large-scale disc but does not have large-scale spiral arms.
In physical cosmology, a protogalaxy, which could also be called a " primeval galaxy ", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral ...
Elliptical galaxies have central supermassive black holes, and the masses of these black holes correlate with the galaxy's mass. Elliptical galaxies have two main stages of evolution. The first is due to the supermassive black hole growing by accreting cooling gas. The second stage is marked by the black hole stabilizing by suppressing gas ...
Galactic bulge. Artist's impression of the central bulge of the Milky Way [1] In astronomy, a galactic bulge (or simply bulge) is a tightly packed group of stars within a larger star formation. The term almost exclusively refers to the central group of stars found in most spiral galaxies (see galactic spheroid ).
The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9 × 10 19 kilometres ), [1] and a total mass of the order of 2 × 10 12 solar masses (4 × 10 42 kg). [2] It consists of two collections of galaxies in a "dumbbell" shape; the Milky ...