Spiral & Barred Spiral Galaxies

15.6 - Be able to classify galaxies using the Hubble classification system, including:
a) spiral
b) barred spiral

These are flattened disc galaxies consisting of a nucleus of stars from which spiral arms extend.

There are two types:

  1. Spiral Galaxies. The spirals arms wind around the nucleus.
  2. Spiral Barred (or Barred Spiral) The spirals extend from a bar through the nucleus.

Typically older stars are nearer the nucleus while younger stars are further out in the spiral arms.

 

Questions

What is the difference between a spiral and a barred spiral galaxy?

Links

Astronomy Picture of the Day Spiral Galaxies

SEDS Spiral Galaxies