Disc galaxy
Encyclopedia
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
which have discs, a flattened circular volume of stars. These galaxies may, or may not include a central non-disc-like region (central bulge).
Disc galaxy types include
- spiral galaxies
- barless spiral galaxiesUnbarred spiral galaxyAn unbarred spiral galaxy is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy. It is designated with an SA in the galaxy morphological classification scheme.The Sombrero Galaxy is an unbarred spiral galaxy....
(type S, SA) - barred spiral galaxiesBarred spiral galaxyA barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies...
(type SB) - intermediate barred spiral galaxies (type SAB)
- barless spiral galaxies
- lenticular galaxiesLenticular galaxyA lenticular galaxy is a type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes. Lenticular galaxies are disk galaxies which have used up or lost most of their interstellar matter and therefore have very little ongoing...
(type E8, S0, SA0, SB0, SAB0)