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
Gas giant Hot Jupiters are class IV or V. A cold hydrogen-rich gas giant more massive than Jupiter but less than about () will only be slightly larger in volume than Jupiter. For masses above , gravity will cause the planet to shrink (see degenerate matter). Kelvin–Helmholtz heating can cause a gas giant to radiate more energy than it receives from its host star. Although the words "gas" and "giant" are often combined, hydrogen planets need not be as large as the familiar gas giants from the Solar System. However, smaller gas planets and planets closer to their star will lose atmospheric