Description: Stars that are fusing helium to carbon in their cores are called horizontal branch stars. The name arises because these stars lie along a horizontal branch in the Hertzsprung–Russell diagram, displaying a range of "surface" temperatures (effective temperatures) but nearly constant luminosity. These are stars that have evolved beyond the red giant phase with variable amounts of mass (outer layers) lost. Main sequence stars with mass up to eight times the mass of the Sun can go through this evolutionary phase.

Related Terms:

• Main Sequence
• Red Giant
• Stellar Evolution
• Effective Temperature

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

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