Horizontal branch

The horizontal branch (HB) is a stage of stellar evolution which immediately follows the red giant branch. HB stars are powered by helium fusion (aka the triple-alpha reaction) in their cores, and hydrogen fusion in a shell surrounding the core. The horizontal branch is so named because HB stars lie along a roughly horizontal line in a color-magnitude diagram.


This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia article. Browse Wikipedia for more information.