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.

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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)

• thick disk
• thin disk