Galaxies

Galaxy

A massive gravitational system containing stars, planetary systems, stellar remnants, gas, dust, and dark matter.

Elliptical Galaxy

A type of galaxy with a smooth elliptical shape, even light distribution, mostly old stars, and very low star formation.

Spiral Galaxy

A galaxy characterized by a flattened rotating disk, spiral arms, and a central bulge of stars.

Lenticular Galaxy

A galaxy that is intermediate between elliptical and spiral, with a central bulge and disk but no spiral arms.

Irregular Galaxy

A galaxy with no definite shape, random star arrangement, large amounts of gas and dust, and high star formation.

Dwarf Galaxy

Small galaxies, often satellites of larger galaxies, contains few billion stars.

Barred Spiral Galaxy

A spiral galaxy that contains a bar-shaped structure through its nucleus.

Peculiar Galaxy

A galaxy with an unusual structure formed through gravitational interactions or mergers.

Supermassive Black Hole

A massive black hole often found at the centers of galaxies.

Hubble Classification System

A method of categorizing galaxies developed by Edwin Hubble, classifying them into four main types: elliptical, spiral, lenticular, and irregular.

Galaxy Cluster

A large gravitationally bound collection of galaxies, consisting of 50 to 1000 or more galaxies.

Intracluster Medium

Hot ionized hydrogen and helium gas found in galaxy clusters.

Compact Group

A small collection of galaxies that are gravitationally bound together, usually about 5 galaxies.

Fossil Group

Remnants of older merged galaxy groups, often containing dwarf galaxies.

Proto Group

Galaxy groups that are still forming, containing protogalaxies.

Supercluster

The largest known structures in the universe made from multiple galaxy clusters and groups bound together.

Hubble Tuning Fork

A diagram used by Edwin Hubble to illustrate the classification of galaxies.

Dwarf Spheroidal Galaxy

A type of dwarf galaxy that contains very little or no gas and has no star formation.