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A disc galaxy (or disk galaxy) is a galaxy characterized by a galactic disc. This is a flattened circular volume of stars that are mainly orbiting the galactic core in the same plane.[1] These galaxies may or may not include a central non-disc-like region (a galactic bulge).[2] They will typically have an orbiting mass of gas and dust in the same plane as the stars. Interactions with other nearby galaxies can perturb and stretch the galactic disk.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/NGC_253_Galaxy.jpg/220px-NGC_253_Galaxy.jpg)
Disc galaxy types include:
- Spiral galaxies:
- Unbarred spiral galaxies: (types S, SA)
- Barred spiral galaxies: (type SB)
- Intermediate spiral galaxies: (type SAB)
- Lenticular galaxies: (types E8, S0, SA0, SB0, SAB0)
Galaxies that are not disc types include:
- Elliptical galaxies: (type dE)
- Irregular galaxies: (type dI)
See also
editReferences
edit- ^ "Disk Galaxies | COSMOS". astronomy.swin.edu.au.
- ^ "The Galactic Bulge". burro.case.edu.