Reaction rate and stellar evolution The triple-alpha steps are strongly dependent on the temperature and density of the stellar material. The power released by the reaction is approximately proportional to the temperature to the 40th power, and the density squared. In contrast, the proton–proton chain reaction produces energy at a rate proportional to the fourth power of temperature, the CNO cycle at about the 17th power of the temperature, and both are linearly proportional to the density. This strong temperature dependence has consequences for the late stage of stellar evolution, the red-giant stage.
Reaction rate and stellar evolution The triple-alpha steps are strongly dependent on the temperature and density of the stellar material. The power released by the reaction is approximately proportional to the temperature to the 40th power, and the density squared. In contrast, the proton–proton cha?in reaction produces energy at a rate proportional to the fourth power of temperature, the CNO cycle at about the 17th po?wer of the temperature, and both are linearly pr.oportional to the density. This strong temperature dependence has consequences for !the late stage of stellar evolution, the red-giant stage.