The spiral galaxy is the most common type of galaxy in the universe. The Milky Way is just one of the many spiral galaxies. Our Earth and solar system are located in the Milky Way. Spiral arms are regions of active star formation. These young stars are hot and have a bluish color. Spiral galaxies are found in areas with few galaxies and are uncommon in dense galactic clusters.
Shape
The spiral galaxy resembles a rotating spiral of stars and gases. It typically has a large bulge at the center. The visual result is a galaxy with arms rotating outward from a central bulge.
This central bulge is thought to contain a supermassive black hole. The stars within the bulge are older than the stars in the spiral arms.
Spiral arms are regions of high density. When dust and gases enter the high density arms, they are collapsed into new stars. The new stars are often blue stars which then give the arms their blight blue color.
Age and Color
New stars are actively created in the spiral arms of this type of galaxy. This active creation of new stars makes spiral galaxies young galaxies. Younger galaxies have a bluish color that is given off by young stars.
The image above is a combination of photos using infrared, ultraviolet, visible, and X-rays. This magnifies the differences in the colors of the galaxy. The hottest and youngest stars are located in the purplish regions. The reddish areas are regions of active star formation.
The Earth and our solar system are part of the Milky Way galaxy. The Milky Way is a young spiral galaxy.
Reflections
Vocabulary
- black hole
- density
- spiral galaxy
Notes
- Spiral galaxies have several spiral arms.
- Stars are formed in the spiral arms and the young stars give the galaxy a bluish color.
- The spiral galaxy is considered a young galaxy.
