13. The Realm of the Nebulae

Last: 12. The Milky Way and Other Galaxies

Topics:

Hubble's law
Groups and clusters
Dark matter
Galaxy transformations
Active galaxies

Reading:


Ch. 11	CLUSTERS AND SUPERCLUSTERS (p. 246)
Ch. 11-14	Galaxies are gravitationally bound into clusters and superclusters
Ch. 11-15	Clusters of galaxies may appear densely or sparsely populated and regular or irregular in shape
Ch. 11-16	Galaxies in a cluster can collide and combine
Ch. 11-17	Galactic halos may account for some of the dark matter in the universe
Ch. 11	SUPERCLUSTERS IN MOTION (p. 252)
Ch. 11-18	The redshifts of superclusters indicate that the universe is expanding

Web Resources:

Group of galaxies [source]
This is a compact group of spiral and elliptical galaxies. While groups of galaxies are common, only a small fraction are as compact as the one shown here.
Hercules cluster [source]
The Hercules cluster is unusually rich in spiral galaxies. A number of interacting galaxies are visible in this image.
Local Supercluster (0.9 Mbyte mpg) [source]
This animation shows a trip through the Local Supercluster, a region about 80 Mpc in diameter containing a number of galaxy clusters.
Density field [source]
This image shows regions of high galaxy density. The box is about 400 Mpc across.
Redshift survey [source]
These fan-shaped surveys reveal the foam-like texture of the galaxy distribution. The Milky Way is at the point where the two fans meet; each fan extends to a distance of about 800 Mpc.
Halo Formation (2.3 Mbyte mpeg) [source]
This is a computer simulation of the formation of dark halos by gravitational collapse. In this animation, color shows density. Note how several small halos merge to form a single larger one; such mergers probably built up the Milky Way's halo more than 10 billion years ago.
The Antennae Galaxies (1.2 Mbyte mpg)
Computer simulation showing how the collision of two disk galaxies could create the famous `Antennae Galaxies'.
Evolution of a Compact Group (2.4 Mbyte mpeg)
Computer simulation showing the interactions and eventual merger of galaxies in a compact group over roughly 4 billion years.
Fate of the Milky Way (3 Mbyte mpeg) [source]
Compuer simulation of a merger of the Milky Way and the Andromeda Galaxy.
Galaxy Transformations
Further computer simulations of galactic collisions.
Stars in the galactic center (0.65 Mbyte gif animation) [source]
This movie shows the motion of stars near the center of the Milky Way over a period of eight years. From the observed motions of these stars we can infer the presence of a massive black hole in the center of our galaxy!

Homework 13: Hubble's Law, due 11/27.

Joshua E. Barnes (barnes@ifa.hawaii.edu)

Last modified: November 20, 2001
http://www.ifa.hawaii.edu/~barnes/ast110/trotn.html