Red-giant branch the star when it reaches the horizontal branch, so the properties of red-clump stars can be used to determine the mass difference before and after the helium flash. Mass lost from red giants also determines the mass and properties of the white dwarfs that form subsequently. Estimates of total mass loss for stars that reach the tip of the red-giant branch are around . Most of this is lost within the final million years before the helium flash. Mass lost by more-massive stars that leave the red-giant branch before the helium flash is more difficult to measure directly. The current
Red-giant branch terminology is still frequently used today. Modern stellar physics has modelled the internal processes that produce the different phases of the post-main-sequence life of moderate-mass stars, with ever-increasingly complexity and precision. The results of RGB research are themselves being used as the basis for research in other areas. When a star with a mass from about (solar mass) to ( for low-metallicity stars) exhausts its core hydrogen, it enters a phase of hydrogen shell burning during which it becomes a red giant, larger and cooler than on the main sequence. During hydrogen shell burning, the interior of the star goes