Spiral arms

Definition

Spiral arms are regions of a spiral galaxy that extend from the center and wind outward in a spiral pattern. They are sites of high star formation activity and contain young, hot stars, gas, and dust.

5 Must Know Facts For Your Next Test

1. Spiral arms are primarily found in spiral galaxies, including the Milky Way.
2. They are formed by density waves that compress gas and trigger star formation.
3. The Milky Way's major spiral arms include the Perseus Arm, the Carina-Sagittarius Arm, and the Scutum-Centaurus Arm.
4. Spiral arms are more prominent in grand-design spirals than in flocculent spirals.
5. Star clusters, nebulae, and molecular clouds are commonly found within spiral arms.

Review Questions

• What are spiral arms and where are they located?
• How do density waves contribute to the formation of spiral arms?
• Name at least two major spiral arms of the Milky Way Galaxy.

Related terms

Density Waves:

Regions of higher density in a galaxy that move through it like ripples on water, triggering star formation.

Grand-Design Spiral Galaxy: A type of spiral galaxy with well-defined and prominent spiral arms.

Nebula:

A cloud of gas and dust in space, often found within spiral arms where new stars are forming.