Many of the well-known bright stars are red giants because they are luminous and moderately common. asymptotic-giant-branch (AGB) stars with a helium burning shell outside a degenerate carbon–oxygen core, and a hydrogen-burning shell just beyond that.red-clump stars in the cool half of the horizontal branch, fusing helium into carbon in their cores via the triple-alpha process.most common red giants are stars on the red-giant branch (RGB) that are still fusing hydrogen into helium in a shell surrounding an inert helium core.Red giants vary in the way by which they generate energy: The appearance of the red giant is from yellow-white to reddish-orange, including the spectral types K and M, sometimes G, but also class S stars and most carbon stars. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K (4,700 ☌ 8,500 ☏) or lower. A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ( M ☉)) in a late phase of stellar evolution.

Red giant universe license