Asymptotic giant branch forming helium (known as hydrogen burning), and a very large envelope of material of composition similar to main-sequence stars. When a star exhausts the supply of hydrogen by nuclear fusion processes in its core, the core contracts and its temperature increases, causing the outer layers of the star to expand and cool. The star becomes a red giant, following a track towards the upper-right hand corner of the HR diagram. Eventually, once the temperature in the core has reached approximately , helium burning (fusion of helium nuclei) begins. The onset of helium burning in the core halts the star's cooling
A-type main-sequence star Doppler shifts induced by orbiting planets since the spectral lines are very broad. However, this type of massive star eventually evolves into a cooler red giant which rotates more slowly and thus can be measured using the radial velocity method. As of early 2011 about 30 Jupiter class planets have been found around evolved K-giant stars including Pollux, Gamma Cephei and Iota Draconis. Doppler surveys around a wide variety of stars indicate about 1 in 6 stars having twice the mass of the Sun are orbited by one or more Jupiter-sized planets, compared to about 1 in 16 for Sun-like