Question: Lecture 32

Answer: Irregular Galaxies and Clusters of Galaxies

Question: Irregular Galaxies

Answer: There are many kinds of irregular galaxies: dwarf irregulars, dwarf spheroidals, starburst galaxies, colliding and interacting galaxies, and galaxies with active galactic nuclei.

Question: The properties of dwarf irregular galaxies:

Answer: Contents: Young and old objects

Masses: 106 to 109 solar masses

Diameters: 1000 to 10,000 pc

Luminosities: 107 to 109 solar luminosities

Rotation: Rotate slowly

Example: The Magellanic Clouds

Question: Other kinds of irregular galaxies:

Answer:

Question: Colliding and Interacting Galaxies:

Answer:

Question: Clusters of Galaxies:

Answer:

Question: Clusters of galaxies can be roughly divided into two types:

Answer: poor (irregular) clusters and rich clusters.

Question: Rich clusters properties:

Answer: Rich Clusters

1000’s of galaxies

Mostly elliptical and S0 galaxies

Diameters = 2 to 4 Mpc

Strong, diffuse X-ray sources

Question: Poor Clusters properties:

Answer: Poor Clusters

10 to 1000’s of galaxies

Galaxies of all types

Diameters = 2 to 4 Mpc

Rarely are X-ray sources

Question: The difference between the two types of clusters is caused by :

Answer: