1. But first dwarf and other special galaxies
When Galaxies Collide
But first dwarf and other special galaxies

2. A companion of the Milky-Way
Dwarf Galaxies
Dwarf Galaxy Leo
A companion of the Milky-Way
Dwarf Galaxies are very small Only a few billion stars! Most are elliptical… None are spiral.

3. Active Galaxies
Have central cores that give off abnormal amounts of energy.
About 10% of Galaxies are active
There are three types
Radio
Seyfert (See-furt)
Quasars
All seem to be powered by super-massive black holes

4. Radio Galaxies Center gives off energy in the radio spectrum
Caused by electrons moving near the speed of light.
Electrons are shot out in two jets creating radio producing “radio lobes”

5. Seyfert Galaxies
An Area within less than a light year of the center gives off as much visible light as the rest of the galaxy
Core ejects clouds of gas at as much 10,000 km/sec ( about 3% of the speed of light!)
Some are also Radio Galaxies

6. Quasars Short for quasi-stellar radio source
Give off as much as 1000 times the energy the Milky-Way does!
As much as 10 billion LY away, on the edge of the Universe…thus from the beginning of time!
Few details due to extreme distance
Send out jets of gas at seemingly faster than light speeds

7. When Galaxies Collide Individual stars almost never collide
In Collisions Larger Galaxies are formed:
Disk galaxies (S0) merge with surrounding globular clusters
Disks collide to form both elliptical and spiral galaxies
Colliding spirals may lose integrity and become elliptical
In about four billion years …
The Milky Way will collide with Andromeda!

8. We know this because:
More distant(thus older) groups of galaxies have …
More and smaller galaxies in the same volume
and
More Spirals