What types of galaxies do we find in the universe?

At the moment, we consider common types of galaxies and we ask about characteristics of galaxies that you can see with visible light.

There are four main classes (as classified by Hubble).

  1. Spiral galaxies.
  2. Barred spiral galaxies.
  3. Elliptical galaxies.
  4. Irregular galaxies.

How did galaxies get that way?

Galaxies often come in interacting groups

One nice example consists of M81, M82, and NGC3077. Recall that we looked at the irregular galaxy M82 earlier. Here is M81 by itself. Note the big arm going down to the left, where NGC3077 is. Here is a picture of M81 and M82 . Here is a picture of the M81 group taken with radio wavelengths. Notice the gas connecting the three galaxies.

Galaxies often come in clusters

Here is the Virgo Cluster

Let's look at far away galaxies in a Hubble Space Telescope photo.

Here is a close up view.

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu