Elliptical Galaxies
Elliptical galaxies are also named because of their shapes. Elliptical
galaxies range from circular (remember, a circle is an ellipse!) to long,
narrow, and cigar-shaped.
Elliptical galaxies are denoted by the letter E. They are also
given a number from 0 to 7. An E0 galaxy looks like a circle.
An E7 galaxy is very long and thin. Astronomers have specific
mathematical definitions for each number, but these definitions are
beyond the scope of this project. With some practice,
you can learn to visually tell what type of elliptical
galaxy you are observing.
Elliptical galaxies have a large range of sizes. The largest
elliptical galaxies can be over a million light-years in diameter.
The smallest "dwarf elliptical" galaxies are less than one-tenth the size of the Milky Way!
Elliptical galaxies have very little gas and dust. Since stars form
from gas, little star formation occurs in elliptical galaxies. Most
of their stars are old and red. |