Giants

Definition

Giants are stars with significantly larger radii and luminosities compared to main-sequence stars of the same temperature. They have expanded outer layers and a more diffuse structure, often resulting from the exhaustion of hydrogen in their cores.

5 Must Know Facts For Your Next Test

1. Giants can be classified into subcategories such as red giants and blue giants based on their temperatures and colors.
2. The expansion into a giant phase occurs when a star exhausts the hydrogen in its core, causing it to burn helium or heavier elements.
3. Spectra of giant stars show strong absorption lines, which help determine their chemical composition and surface gravity.
4. The luminosity of giant stars can be hundreds to thousands of times greater than that of the Sun.
5. Giant stars play a crucial role in enriching the interstellar medium with heavy elements through stellar winds and supernova explosions.

Review Questions

• What triggers the transformation of a star into a giant?
• How do astronomers use spectra to determine the composition of giant stars?
• Why are giant stars more luminous than main-sequence stars?

Related terms

Main Sequence Star:

A star that is fusing hydrogen in its core and lies on the main sequence of the Hertzsprung-Russell diagram.

Red Giant:

A type of giant star that has a relatively low surface temperature and high luminosity due to its large radius.

Supergiant:

An extremely large and luminous star, much bigger than a giant, often marking the final evolutionary stages before becoming a supernova or collapsing into a black hole.