The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's...

the cool half of the horizontal branch, fusing helium into carbon in their cores via the triple-alpha process asymptotic-giant-branch (AGB) stars with a...

period on the horizontal branch with a helium-fusing core. Many of these helium-fusing stars cluster towards the cool end of the horizontal branch as K-type...

giant branch (AGB). The RR Lyrae variable stars, usually with spectral types of A, lie across the middle of the horizontal branch. Horizontal-branch stars...

itself, the horizontal branch, and the AGB, and the evolutionary state of the stars in these regions was broadly understood. The red-giant branch was described...

envelope contracts again, and the star moves from the red-giant branch to the horizontal branch., chapter 6. When the core helium is exhausted, a star with...

lifespans, first by burning hydrogen (main sequence star), then helium (horizontal branch star), and progressively burning higher elements. However, this does...

field stars (e.g. the Hipparcos stars). The red clump giants are cool horizontal branch stars, stars originally similar to the Sun which have undergone a...

star instead moves down and leftwards in the HR diagram. This is the horizontal branch (for population II stars) or a blue loop for stars more massive than...

on the red-giant branch (RGB) have an inert helium core and remain on the RGB until a helium flash moves them to the horizontal branch. However, stars...