Larger stars generally have higher core temperatures due to the need for greater pressure gradients to maintain hydrostatic equilibrium. Core temperatures in massive stars can reach around a billion kelvins, particularly during processes like silicon burning, which occurs before a supernova event. While stars like the Sun primarily rely on the proton-proton chain at about 15 million kelvins, more massive stars utilize different fusion processes that require higher temperatures. The temperature also depends on the type of fuel being burned, with hydrogen burning stars not reaching billions of degrees. Ultimately, the mass of a star significantly influences its core temperature and fusion processes.