A horizontal strip of stars in the Hertzsprung–Russell diagram of globular clusters, comprising stars somewhat bluer and fainter than those on the giant branch. These stars are thought to be burning helium in their core and hydrogen in a surrounding shell. They are of 0.6–0.8 solar masses, of which more than half is in the helium-burning core, and have probably lost substantial mass through stellar winds during their giant phase. Stars typically spend 50–100 million years on the horizontal branch.
Subjects: Astronomy and Astrophysics.