Elliptical Galaxies

An elliptical galaxy is a type of galaxy that is characterized by its smooth, featureless appearance and its ellipsoidal shape. These galaxies are made up of old stars, with very little ongoing star formation and little to no interstellar matter. They are the most common type of galaxy in the universe, and they come in a range of sizes from small dwarfs to giant supergiants.

Characteristics of Elliptical Galaxies

Elliptical galaxies are classified according to their shape, from E0 (nearly spherical) to E7 (highly elongated). The larger the number after the "E," the more elongated the galaxy. They are primarily composed of old, red stars and lack the gas and dust necessary for new star formation. Elliptical galaxies also have very little in the way of spiral arms or other structures. They are often found in the central regions of galaxy clusters.

Formation of Elliptical Galaxies

The current understanding is that elliptical galaxies form through the mergers of smaller galaxies. When two or more galaxies collide, the gas and dust within them are compressed, triggering a burst of star formation. Over time, these galaxies merge to form a larger, featureless elliptical galaxy. This process is known as hierarchical galaxy formation.

Fun Facts about Elliptical Galaxies

Elliptical galaxies are often referred to as "early-type" galaxies, as they are thought to have formed early in the universe's history.
The largest known galaxy, IC 1101, is an elliptical galaxy located about a billion light-years from Earth.
Elliptical galaxies are often found at the centers of galaxy clusters, where they have undergone many mergers and interactions with other galaxies.