GAL - Superclusters LESSON

Superclusters

Superclusters are essentially a cluster of galaxies. They consist of smaller galaxy groups. The Milky Way Galaxy is part of the Local Group Cluster which contains more than 54 galaxies. The Local Group Cluster is in turn part of the Laniakea Supercluster. This supercluster is estimated to span 500 million light years. The Local Group Cluster is only about 10 million light years.

The image above shows the universe within 500 million light years. You can see some of the superclusters that surround the Virgo Supercluster (located in the middle of the image). Although they are not isolated in space, they instead make up "walls" that surround large voids. Review the image to see some of the largest voids and walls that superclusters create in our universe.

Active Galactic Nuclei (AGNs)

These are tiny regions at the center of galaxies. They emit abnormally large amounts of energy that fluctuate in intensity. At least 10% of galaxies in the universe have AGNs.

Quasars

These are very luminous, distant AGNs. They get their name from the contraction of quasi-stellar radio source. They are 100,000 times more luminous than the Milky Way Galaxy! Quasars, however, are very small.

Calculating distances of galaxies and superclusters is tricky. This is because they are often millions of light years from each other. When we look at distances of galaxies we have to look at the light they emit. We have learned previously that light comes in different wavelengths. Splitting the light from a galaxy with a prism allows us to see its spectrum. The visible spectrum of most galaxies will appear as a broad band of light at most wavelengths with some absorption lines. These lines occur at very specific wavelengths or colors.

 

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